WO2024206388A1

WO2024206388A1 - Efficient, low-energy, low waste alkylation and arylation method for producing safe, enviromentally-friendly disubstituted diphenylamine antioxidants

Info

Publication number: WO2024206388A1
Application number: PCT/US2024/021607
Authority: WO
Inventors: Huiyuan Chen; Travis BENANTI; David SPIRA; Allan NORRIS; Robert G. Rowland; Cyril Migdal
Original assignee: Lanxess Corporation
Priority date: 2023-03-31
Filing date: 2024-03-27
Publication date: 2024-10-03

Abstract

Liquid di-alkylated diphenylamine and/or alkylated, arylated di-substituted diphenylamine compositions are disclosed containing a high concentration of di-alkylated diphenylamine and low levels of mono-substituted and tri-substituted diphenylamine and less than 0.1% by weight of unsubstituted diphenylamine. The novel compositions may be prepared by controlled alkylation of diphenylamine with at least one first olefin followed by removal of first olefins by distillation and subsequent alkylation with at least one second olefin that can effectively reduce unsubstituted diphenylamine amine to less than 0.1% by weight and mono-substituted diphenylamine and di¬ substituted diphenylamine with low molecular weights to no more than 7% by weight. The liquid di-alkylated diphenylamine and/or alkylated, arylated di-substituted diphenylamine compositions disclosed are considered to be safe and environmentally friendly, and their methods of manufacture have high reactor efficiency and consume low energy, and generate low waste.

Description

EFFICIENT, LOW-ENERGY, LOW WASTE ALKYLATION AND ARYLATION METHOD FOR PRODUCING SAFE, ENVIROMENTALLY-FRIENDLY DISUBSTITUTED DIPHENYLAMINE ANTIOXIDANTS

Certain alkylated and arylated diphenylamines are well known as antioxidants for a variety of fuels and lubricants, such as mineral oils and synthetic oils. Alkylated diphenylamines (ADPAs) and arylated diphenylamines may primarily be used in transportation and industrial lubricant applications at high temperature or other more stressful operating environments. For example, ADPA antioxidants may be used to suppress oxidation and maintain performance of engine oils, industrial oils, gear oils, hydraulic fluids, turbine oils and greases.

There are numerous methods for producing liquid alkylated and/or alkylated, arylated diphenylamine compositions containing a significant amount of di-substituted diphenylamine. For example, U.S. Patent No. 6,315,925, U.S. Patent No. 6,355,839, and EP 2,003,115 describe the preparation of such compositions using a complex mixture of isomeric olefins, like nonenes (propylene trimer), as alkylating agents in a single-step reaction. The resulting monoalkyl and dialkyl diphenylamine components derived from the isomeric mixture of propylene or butene oligomers remain in stable liquid form at ambient temperature. U.S. Patent No. 2,530,769 and U.S. Patent No. 4,824,601 disclose methods of preparing mixed derivatives of diphenylamine (DPA) by alkylating DPA with a mixture of two olefins in a single-step reaction process. U.S. Patent Nos. 2,943,112 and 6,204,412 disclose methods of preparing mixed derivatives of diphenylamine by alkylating diphenylamine sequentially with two olefins in a two-step reaction process. These processes can only produce liquid alkylated DPA compositions comprising less than 80 wt% di-alkylated DPA and greater than 0.1 wt% residual unsubstituted DPA, more often, greater than 0.25 wt% residual unsubstituted DPA, and greater than 10% by weight monosubstituted DPA, based on the total weight of substituted and unsubstituted DPA in the composition.

U.S. Patent No. 4,798,684 and U.S. Patent No. 9,890,346 disclose preparing liquid di-substituted DPA comprising di-alkyl diphenylamine in greater than 80% by weight by using two olefins in a two-step alkylation process. Due to the catalyst selection and/or reaction conditions, the resulting compositions contain objectionable amounts of mono-alkylated DPA and unsubstituted DPA. These toxic components either persist in the final product composition after isolation or necessitate distillation at high vacuum and temperature to be removed. Specifically, the process disclosed in U.S. Patent No. 4,798,684 applies a temperature greater than 180 °C in the two olefin alkylation steps, causing the generation of an objectionable amount, e.g. more than 10 wt%, most likely up to 20 wt%, of monobutyl and dibutyl DPA and more than 1 wt% of unsubstituted DPA in the final product. In addition, the process consumes a high amount of energy and generates deactivated solid acid clay catalyst that may not be recycled. The process disclosed in U.S. 9,890,346 generates aqueous waste from metal halide catalyst. The catalyst cannot be recovered. The process also generates a large amount of organic waste because of using an excessive amount of olefins for inhibiting dealkylation and distillation of greater than 17% by weight of the product. The distillate comprises diphenylamine, mono-alkyl diphenylamine and dialkyl diphenylamine of low molecular weight. In addition, the process consumes high amount of energy and is low in the efficiency of reactor usage.

For many years, aminic antioxidants were considered to be high-performing chemicals that were safe to humans and the environment. However, diphenylamine based commercial aminic antioxidants and the components of monoalkylated and unsubstituted DPA in their compositions have come under increased environmental and safety scrutiny. The first reports of reproductive/developmental toxicity emerged from the findings of the 2014 OECD 422 study involving Irganox® L57, Naugalube® 750, and similar commercial products. Subsequently in 2021 , diphenylamine was classified as potentially carcinogenic (2B). Since that time, an increasing number of toxicity and environmental fate studies have revealed evidence that two widely used diphenylamine-based commercial antioxidants may lead to reproductive toxicity in humans following skin or oral exposure and also pose a potential risk of chronic aquatic toxicity to waterdwelling species through dispersion. These two groups of commercial alkylated diphenylamine products comprise residual diphenylamine, with a concentration ranging from greater than 0.1% to less than or equal to 2% by weight, along with 15% to 50% by weight of monoalkyl diphenylamine, 50 to 80% by weight dialkyl diphenylamine, and less than 15% by weight of trialkyl diphenylamine in their formulations. They are associated with trade names such as Irganox® L57, Irganox® L67 Naugalube® 750, Naugalube® 438L, Lubrizol® 5161 , Songnox® L670, Songnox® L570, Rianox® 5057, Rianox® 5067, Yablub® DND.

In a recently published harmonized classification and labelling (CLH) proposal by ANSES (the French Agency for Food, Environmental, and Occupational Health & Safety), the modeled LogKow, water solubility, and toxicokinetic parameters of the primary constituents in the compositions of these two families of antioxidants were documented. The data, initially derived from a 2016 OECD report, indicate that the constituents of monoalkyl DPA (butyl-, octyl-, and nonyl-) as well as dibutyl diphenylamine have lower molecular weights, for instance, below 300 Dalton, lower LogKow values less than 8, and higher water solubility compared to the components of dioctyl and dinonyl diphenylamine. Consequently, their oral bioavailability and toxicokinetic parameters, as measured by AUC O-inf* (Area under the curve from 0 to infinity), are significantly higher than those of the constituents of dialkyl diphenylamines with molecular weights exceeding 300 Daltons. The modeling outcomes, along with the findings disclosed in WO 2023209038 A1 , suggest that mono-substituted diphenylamines, regardless of their molecular weights, and disubstituted diphenylamines with low molecular weights below about 300 Daltons, have a significantly higher potential to pose hazards to humans and the environment compared to disubstituted diphenylamines. This trend is also reflected in the results of reproductive toxicity screening tests (OECD 421) conducted on Irganox® L57 and Irganox® L67, highlighting the correlation between bioavailability and the presence of mono-substituted diphenylamines and disubstituted diphenylamines with molecular weights below about 300 Daltons in diphenylamine- based antioxidant compositions.

While the previously mentioned two commercial liquid alkylated diphenylamines are classified as hazardous substances due to their reproductive toxicity, commercially available alkylated and arylated diphenylamine products like Naugalube® 438, Vanlube® 81 , Naugalube® AMS, and Dusantox® 86 are not classified as such. These products contain less than 0.1% by weight of unsubstituted diphenylamine, less than 6% by weight of mono-substituted diphenylamine, typically less than 1% (often less than 0.2%) by weight of di-substituted diphenylamine with molecular weights below 300 Daltons, and often more than 85% by weight of di-substituted diphenylamines with higher molecular weights than 300 Daltons. However, these products are all in solid form at room temperature (25 °C). Compared to liquid additives, solid-form additives are generally less favorable. Solid-form additives often necessitate extra processing, e.g., heating to above their melting points, and/or safety precautions during use (blending into lubricant formulations); they can be inconvenient and less efficient in terms of storage and handling compared to additives that are liquid at room temperature.

Based on current guidance in regulation and product safety standards, safe and environmentally- friendly di-alkylated diphenylamine and/or alkylated, arylated di-substituted diphenylamine should have unobjectionable amounts of unsubstituted diphenylamine and mono-substituted diphenylamine and di-substituted diphenylamine with molecular weight less than 300 Daltons. An unobjectionable amount of unsubstituted diphenylamine is less than 0.1 % by weight, e.g., less than 0.02 wt %, based on the total amount of unsubstituted diphenylamine and substituted diphenylamines. An unobjectionable amount of mono-substituted diphenylamine and disubstituted diphenylamine with molecular weight less than 300 Daltons is less than 7 % by weight, e.g. less than 5 wt %, less than 3 wt%, based on the total amount of unsubstituted diphenylamine and substituted diphenylamines. In addition, it is advantageous that the safe and environmentally-friendly alkylated and arylated diphenylamines are in liquid form at ambient temperature (25 °C) for the benefits of convenient and safe material handling. Safe and environmentally-friendly alkylated and arylated diphenylamines are commercially available, such as the aforementioned Naugalube® 438, Vanlube® 81 , Naugalube® AMS, and Dusantox® 86. However, these products are solids at 25 °C. As a result, there is an unmet need in the industry to produce di-alkylated diphenylamine and/or alkylated, arylated di-substituted diphenylamine compositions in liquid form, utilizing a low-energy and environmentally friendly process, that offer both effective antioxidant properties and reduced toxicity to humans and the environment.

In this context, the composition and manufacturing methods of the present disclosure meet these needs, overcoming the above-discussed limitations in the art. In particular, the present disclosure relates to an efficient, low energy consuming, low hazardous waste process of producing a dialkylated diphenylamine and/or alkylated, arylated di-substituted diphenylamine compositions that meet specific technical performance targets set by industry standards and are less toxic to humans and the environment when compared to commercially available liquid alkylated DPA products, such as, for example Irganox® L57, Irganox® L67, Naugalube® 438L, or Naugalube® 750.

SUMMARY OF THE INVENTION

According to an aspect of the present invention, an efficient, low energy consuming, low hazardous waste process of producing a di-alkylated diphenylamine and/or alkylated, arylated di-substituted diphenylamine composition is provided. The process may comprise

(i) reacting a reaction mixture comprising unsubstituted diphenylamine, a first olefin comprising a mixture of alkene isomers chosen from propylene oligomers and butene oligomers, and an acid catalyst, such as acid clay catalyst, to form an intermediate reaction mixture comprising an isomeric mixture of di-substituted diphenylamine of formula I,

mono-substituted diphenylamine of formula IV,

and residual unsubstituted diphenylamine, wherein Ri is derived from the mixture of the first olefin,

(ii) distilling more than 90%, e.g. more than 95%, of any unreacted portion of the mixture of alkene isomers, and

(iii) adding at least one second olefin chosen from olefins of formulas

styrene vinylidene Isomer 1 of vinylidene Isomer 2 of vinylidene or a-alkylstyrene where each of R’i and R’2 is independently H or straight-chain or branched C1-12 alkyl, (e.g. C4-12 alkyl) and R’₃ is H or straight-chain or branched C1.4 alkyl, to the intermediate reaction mixture, and reacting the intermediate reaction mixture in the presence of an acidic alkylation catalyst to produce the di-alkylated diphenylamine and/or alkylated, arylated di-substituted diphenylamine composition, wherein the proportion in the reaction mixture that is alkylated by the mixture of the first olefin in step (i) and the extent of residual unsubstituted diphenylamine that is alkylated by the second olefin in step (iii) are controlled such that the resulting di-alkylated diphenylamine and/or alkylated, arylated di-substituted diphenylamine composition comprises: (1) at least 90% by weight of a mixture of di-alkylated diphenylamine of formulas I, II and III

I II III in various ratios, based on the total weight of unsubstituted and substituted diphenylamine in the composition, wherein Ri is derived from the mixture of the first olefin and R2 is derived from the at least one second olefin,

(2) less than 0.1% by weight of unsubstituted diphenylamine, based on the total weight of unsubstituted and substituted diphenylamine in the composition,

(3) less than 7% by weight of a mixture of

(a) mono-substituted diphenylamine of formulas IV and V

wherein R1 is derived from the mixture of the first olefin and R2 is derived from the at least one second olefin and

(b) di-substituted diphenylamine with molecular weight less than 300 Daltons, based on the total weight of unsubstituted and substituted diphenylamine in the composition, and

(4) less than 5% by weight of tri-substituted diphenylamine, based on the total weight of unsubstituted and substituted diphenylamine in the composition, wherein the composition is a liquid at ambient temperature, e.g. about 20 to about 25 °C.

The resulting di-alkylated diphenylamine and/or alkylated, arylated di-substituted diphenylamine composition may contain at least 95% by weight, based on the total weight of unsubstituted and di-substituted diphenylamine in the composition, of a mixture of di-substituted diphenylamine of formulas 1, 11 and III. At least 70% by weight, preferably at least 80% by weight, of the mixture of di-alkylated diphenylamine may comprise para, para’ di-substituted diphenylamine. The resulting di-alkylated diphenylamine and/or alkylated, arylated di-substituted diphenylamine composition may contain less than 0.02% by weight, based on the total weight of unsubstituted and substituted diphenylamine in the composition, of unsubstituted diphenylamine.

The resulting di-alkylated diphenylamine and/or alkylated, arylated di-substituted diphenylamine composition may contain less than 5% by weight of a mixture of mono-substituted diphenylamine and di-substituted diphenylamine with molecular weight less than 300 Daltons, based on the total weight of unsubstituted and substituted diphenylamine in the composition.

The resulting di-alkylated diphenylamine and/or alkylated, arylated di-substituted diphenylamine composition may contain less than 3% by weight of a mixture of tri-substituted diphenylamine, based on the total weight of unsubstituted and substituted diphenylamine in the composition.

The at least one second olefin may be chosen from diisobutylene, styrene, a-methylstyrene, a- alkylstyrene, 2-methyl butene-1 , 2-methyl butene-2, 2,4,4-trimethyl pentene-1 , 2,4,4-trimethyl pentene-2, or commercial grade diisobutylene.

In step (i), the reaction mixture may be reacted at a temperature range from about 120 to about 170 °C, often from about 135 to about 165 °C, more often from about 145 to about 160 °C. In step (iii), the reaction mixture may be reacted at a temperature range from about 80 to about 150 °C, often from about 100 to about 140 °C, or from 115 to about 135 °C.

According to another aspect of the present invention, a lubricating oil composition is provided. The lubricating oil composition may comprise (A) a lubricating oil and (B) the di-alkylated diphenylamine and/or alkylated, arylated di-substituted diphenylamine composition disclosed herein in an amount effective to provide antioxidant activity. The di-alkylated diphenylamine and/or alkylated, arylated di-substituted diphenylamine composition present in the lubricating oil composition may be from about 0.1 to about 10 wt%, based on the total weight of the lubricating oil composition. According to an additional aspect of the present invention, a process of manufacturing safe and environmentally friendly di-alkylated diphenylamine and/or alkylated, arylated di-substituted diphenylamine compositions is provided. The process may comprise reacting a reaction mixture comprising di-alkylated diphenylamine, mono-alkylated diphenylamine and less than 25 wt% unsubstituted diphenylamine, an acid alkylation catalyst, preferably an acid clay catalyst, and at least one olefin chosen from olefins of the formulas

styrene vinylidene Isomer 1 of vinylidene Isomer 2 of vinylidene or a-alkylstyrene where each of R’i and R’₂ is independently H or straight-chain or branched C1-12 alkyl, (e.g. C4-12 alkyl) and R’₃ is H or straight-chain or branched C1.4 alkyl, to produce a di-alkylated diphenylamine and/or alkylated, arylated di-substituted diphenylamine composition, wherein the resulting di-alkylated diphenylamine and/or alkylated, arylated di-substituted diphenylamine composition comprises:

(1) at least 90% by weight of a mixture of di-alkylated diphenylamine of formulas I, II, and III

I II III in various ratios, based on the total weight of unsubstituted and substituted diphenylamine in the composition, wherein R1 is derived from the mixture of alkene isomers of propylene oligomers and/or butene oligomers and R₂ is derived from the at least one olefin chosen from olefins of the following formulas

styrene vinylidene Isomer 1 of vinylidene Isomer 2 of vinylidene or a-alkylstyrene

(3) less than 7% by weight of a mixture of

(a) mono-substituted diphenylamine of formulas IV and V

wherein Ri is derived from the mixture of alkene isomers of propylene oligomers and/or butene oligomers and R2 is derived from the at least one olefin, and

(4) less than 5% by weight of a mixture of tri-substituted diphenylamine, based on the total weight of unsubstituted and substituted diphenylamine in the composition, wherein the composition is a liquid at ambient temperature, e.g., about 20 to about 25

The resulting di-alkylated diphenylamine and/or alkylated, arylated di-substituted diphenylamine composition may contain at least 95% by weight, based on the total weight of unsubstituted and di-substituted diphenylamine in the composition, of a mixture of di-substituted diphenylamine.

Further, at least 70% by weight, preferably at least 80% by weight, of the mixture of di-alkylated diphenylamine may comprise para, para’ di-substituted diphenylamine. The resulting di-alkylated diphenylamine and/or alkylated, arylated di-substituted diphenylamine composition may contain less than 0.02% by weight, based on the total weight of unsubstituted and substituted diphenylamine in the composition, of unsubstituted diphenylamine.

The resulting di-alkylated diphenylamine and/or alkylated, arylated di-substituted diphenylamine composition may contain less than 5% by weight of a mixture of mono-alkylated diphenylamine and di-substituted diphenylamine with molecular weight less than 300 Daltons, based on the total weight of unsubstituted and substituted diphenylamine in the composition.

The reaction mixture may be reacted at a temperature range from about 80 to about 150 °C, often from about 100 to about 140 °C, often from 115 to about 135 °C.

In addition, the at least one olefin may be chosen from diisobutylene, styrene, a-methylstyrene, a-alkylstyrene, 2-methyl butene-1 , 2-methyl butene-2, 2,4,4-trimethyl pentene-1 , 2,4,4-trimethyl pentene-2, or commercial grade diisobutylene.

According to another aspect of the present invention, use of a di-alkylated diphenylamine and/or alkylated, arylated di-substituted diphenylamine composition, produced by the processes described herein, in a lubricating oil composition in an amount effective to provide antioxidative activity and to reduce and/or prevent toxicity of the lubricating oil composition is provided.

DETAILED DESCRIPTION

Throughout the present application, “a” or “an” means one or more than one unless indicated otherwise.

For purposes of the present disclosure, “di-substituted DPA” refers to di-alkylated diphenylamine and/or alkylated, arylated di-substituted diphenylamine composition. Di-alkylated, di-arylated, and/or alkylated, arylated disubstituted (e.g. di-substituted DPA of formula II below) may also be referred to as to di-substituted, and tri-alkylated and/or tri-arylated may also be referred to as tri- substituted. Further, mono-alkylated and/or mono-arylated may also be referred to as monosubstituted. Unless otherwise specified, “substituted diphenylamine” and “substituted DPA” refer to both single molecular species as well as mixtures of chemically similar components e.g., “disubstituted diphenylamine” is equivalent to “di-substituted diphenylamines.”

In one aspect, the present disclosure is directed to a di-substituted DPA composition comprising, based on the total weight of substituted and unsubstituted DPA compounds in the liquid di-substituted DPA composition, from about 90% to about 100%, often from about 93% to about 100% by weight of one or more di-alkylated or alkyl, aryl di-substituted DPA of formulas I, II, and III

which di-substituted diphenylamines are predominately, e.g., over 70% and often over 80%, para, para’-disubstituted diphenylamines, wherein Ri is derived from a first olefin comprising a mixture of alkene isomers of propylene oligomers and/or butene oligomers and R₂ is derived from at least one second olefin comprising a single olefin or a mixture of olefins that have any of the four structures shown below,

styrene vinylidene Isomer 1 of vinylidene Isomer 2 of vinylidene or a-alkylstyrene where each of R’1 and R’2 is independently H or straight-chain or branched C1-12 alkyl, (e.g.

C4-12 alkyl) and R’3 is H or straight-chain or branched C1-4 alkyl, less than 0.1% by weight, often less than 0.02 wt% or less, of unsubstituted DPA, less than 7% by weight, often less than 5 wt% or less, of mono-alkylated, mono-arylated

DPA of formulas IV and V and di-substituted DPA with molecular weight less than about 300 Daltons

wherein Ri is derived from the mixture of alkene isomers of propylene oligomers and/or butene oligomers and R2 is derived from the at least one second olefin, and less than 5% by weight, often less than 3 wt% of tri- and tetra-substituted DPA (tri- and tetra-alkylated DPA), wherein the substituents of tri- and tetra-substituted DPA are selected from the derivatives of propylene oligomers or butene oligomers and derivatives of a single olefin or a mixture of olefins that have any of the four structures shown below

styrene vinylidene Isomer 1 of vinylidene Isomer 2 of vinylidene or a-alkylstyrene and wherein at least one alkyl or aryl group of at least one of the one or more di-alkylated diphenylamine and alkylated, arylated di-substituted diphenylamine in composition is derived from the derivatives of single olefin or a mixture of olefins that have any structure shown above. In many embodiments, R’1, R’2 and R’3 in any structure shown above may each independently be H, a straight-chain or a branched alkyl group. In certain embodiments R’1 and R’2 may be different. In many embodiments, R’1 and R’2 may be the same. In many embodiments, R’3 is H or straightchain or branched C1-4 alkyl.

The di-substituted DPA compositions of the invention are liquid at ambient temperature, soluble or miscible in many lubricants and polymers, and provide excellent antioxidant activity and deposit control as measured by a TEOST test. For the purposes of the present disclosure, “ambient temperature” means a temperature ranging from about 20 to about 25°C. As used herein in connection with the presently disclosed di-substituted DPA composition, the term “liquid” refers to a liquid physical form, which remains in liquid form after at least 30 days of storage at ambient temperature.

The reactive alkylated DPA composition of the present disclosure comprises about 25% by weight or less of unreacted DPA and about 4% or less by weight of tri-alkylated DPA formed by the reaction of DPA and selected first olefins in the presence of an acid clay catalyst.

In many embodiments, the ratio by weight of first olefin to DPA that is alkylated in the first step is from about 1 to about 7, often from about 2 to about 5.

As understood in the art, and as used herein, each of “propylene trimer,” “propylene tetramer,” and “propylene pentamer” is a complex mixture of branched alkene isomers derived from the oligomerization of propylene. In many embodiments, a first olefin may comprise a mixture of the alkene isomers of propylene oligomers and/or butene oligomers. Propylene trimer, tetramer and pentamer are enriched in C9-, C12- and C15- isomers, respectively. As will be understood in the field, certain amounts of other carbon chain lengths may be present besides the C9 isomers (such as Cs and C10) in the case of propylene trimer, besides the C12 isomers (such as Cn and C13) in the case of propylene tetramer, and besides the C15 isomers (such as C14 and Cie) in the case of propylene pentamer. Propylene trimer, tetramer and pentamer suitable for the present disclosure are known and commercially available or can be prepared by known oligomerization methods. Often, at least 60% by weight, at least 70% by weight, at least 80% by weight or higher of the propylene oligomers will be C9 isomers (in the case of propylene trimer), C12 isomers (in the case of propylene tetramer), or C15 isomers (in the case of propylene pentamer). As understood in the art, and as used herein, each of “butene trimer” and “butene tetramer” is a complex mixture of branched alkene isomers derived from the oligomerization of butene.

In many embodiments, the at least one second olefin is any olefin or mixture of olefins that have any of the structures below

styrene vinylidene Isomer 1 of vinylidene Isomer 2 of vinylidene or a-alkylstyrene where each of R’i, R’₂ may independently be H or straight-chain or branched alkyl group, but the total number of carbon atoms in the second olefin is 5 to 12. In some embodiments, R’i, and R’₂ may be the same. In many embodiments, R’i and R’₂ are not the same. In many embodiments, R’3 is H or straight-chain or branched C1-4 alkyl. The second olefins of the formulas illustrated above are known and commercially available and/or may be prepared by known methods.

Also disclosed herein are processes for producing the di-alkylated diphenylamine and/or alkylated, arylated di-substituted diphenylamine composition of the present disclosure.

In one aspect, a process for producing a di-alkylated diphenylamine and/or alkylated, arylated di- substituted diphenylamine composition comprises:

(i) reacting a reaction mixture comprising unsubstituted DPA, a first olefin comprising a mixture of alkene isomers chosen from propylene trimer, propylene tetramer, propylene pentamer, commercial nonene, commercial propylene tetramer, butene trimer and butene tetramer and an acidic alkylation catalyst to form, at elevated temperature, an intermediate reaction mixture comprising 10 to 30 wt % unreacted first olefin, less than 25 wt %, more often less than 20 wt %, unreacted diphenylamine, and the rest an isomeric mixture of mono-substituted DPA of formula IV

and di-substituted DPA of formula I

and tri-alkylated DPA, based on the total weight of reaction mixture excluding acid clay,

(ii) distilling off the unreacted first olefin from the intermediate reaction mixture to less than 10% by weight, often less than 5% by weight of reactive reaction mixture, and

(iii) adding at least one second olefin chosen from olefins of the following formulas

styrene vinylidene Isomer 1 of vinylidene Isomer 2 of vinylidene or a-alkylstyrene where each of R’i and R’2 is independently H or straight-chain or branched C1-12 alkyl, (e.g. C4-12 alkyl), and R’₃ is H or straight-chain or branched C1-4 alkyl to the intermediate reaction mixture and reacting the intermediate reaction mixture in the presence of an acidic alkylation catalyst to produce a di-substituted DPA composition, wherein the proportion in the reaction mixture that is alkylated by the mixture of alkene isomers in step (i) and the extent of residual unsubstituted DPA that is alkylated by the second olefin in step (ii) are controlled such that the resulting di-substituted DPA composition:

(1) contains at least 90% by weight, e.g., at least 93% by weight or at least 95% by weight, of a mixture of di-alkylated DPA of formulas I, II, and III

based on the total weight of unsubstituted and substituted DPA in the composition, wherein at least 70% by weight, e.g., at least 80% by weight, of the mixture of di-alkylated DPA comprises para, para’ di-substituted DPA,

(2) contains less than 0.1% by weight, e.g., less than 0.02 wt % by weight or non- detectable by gas chromatography, of unsubstituted DPA, based on the total weight of unsubstituted and substituted DPA in the composition,

(3) contains less than 7% by weight, e.g., less than 5% by weight or less than 3% by weight, of a mixture of

(a) mono-alkylated DPA of formulas IV and V

and

(b) disubstituted DPA with molecular weight less than 300 Daltons, based on the total weight of unsubstituted and substituted DPA in the composition, and

(4) contains less than 5% by weight, e.g., less than 3% by weight or less than 1% by weight, of a mixture of tri-alkylated DPA, based on the total weight of unsubstituted and substituted DPA in the composition, wherein the composition is a liquid at ambient temperature.

As described above, in many embodiments, as much as 90% by weight, 95% by weight, or higher of the resulting di-substituted DPA composition, based on the total weight of unsubstituted and substituted DPA in the composition, is a mixture of di-alkylated DPA.

Often, unsubstituted DPA is present in the resulting composition at less than 0.1% by weight, e.g., less than 0.02% by weight or non-detectable by gas chromatography, based on the total weight of unsubstituted and substituted DPA in the composition. Typically, less than 5% by weight, e.g., less than 3% by weight or less than 1% by weight of the resulting composition, based on the total weight of unsubstituted and substituted DPA in the composition, is over-alkylated DPA, particularly DPA bearing 3 or more alkyl substituents, e.g. trisubstituted diphenylamine.

In addition, less than 7% by weight, e.g., less than 5% by weight or less than 3% by weight of the resulting composition, based on the total weight of unsubstituted and substituted DPA in the composition, is mono-alkylated DPA and disubstituted DPAs with molecular weight less than 300 Daltons.

The resulting di-substituted DPA composition in liquid form that is produced by a low-energy and environmentally friendly process, provides both effective antioxidant properties and reduced toxicity to humans and the environment.

The alkylation reactions of steps (i), (ii), and (iii) above are Friedel-Crafts type reactions catalyzed by an acidic catalyst. The acidic alkylation catalysts used in steps (i) and (iii) need not be, but are often, the same. The present disclosure is not limited to any particular type of solid acidic alkylation catalyst and a wide variety of such catalysts for Friedel-Crafts type reactions are known in the art, including mixtures of such catalysts. For example, suitable catalysts include acid clays, zeolite, phosphotungstic acid, and the like. Preferably, the process uses an acid clay catalyst. Acid clay catalysts preferentially facilitate the formation of di-alkylated DPA with further advantages of producing a light colored product. Acid clay catalysts are easy to remove by decanting or filtration and may be reused many times.

Examples of suitable acid clays include acid activated clays based on bentonite, such as F-20X, F-24X, and F-25X from EP Engineered Clays, and Tonsil® from Clariant, Montmorillonite K-10, K30, APC from Sud-Chemie, Envirocat® EPZ-10, EPZG or EPIC produced by Contract Chemicals and acid activated phyllosilicates, for example those commercially available under the name Fulcat®from BYK division of ALTANA, such as Fulcat®-22 B, -22F, and -435.

In step (i), a reaction mixture comprising unsubstituted DPA, a first olefin comprising a mixture of alkene isomers chosen from propylene trimer, propylene tetramer and propylene pentamer, commercial nonene, commercial propylene tetramer, butene trimer, butene tetramer and an acidic alkylation catalyst is reacted to form an intermediate reaction mixture comprising an isomeric mixture of di-substituted DPAs, residual unsubstituted DPA, unreacted first olefin and acid clay catalyst. The mixture of alkene isomers in the reaction mixture may be propylene trimer, propylene tetramer, propylene pentamer, commercial nonene, commercial propylene tetramer, butene trimer, butene tetramer or any combination thereof, as described herein. In many embodiments, the mixture of alkene isomers is chosen from propylene trimer, propylene tetramer, commercial nonene and commercial propylene tetramer. Often, the mixture of alkene isomers is commercial nonene and commercial propylene tetramer. Often, the mixture of alkene isomers is commercial nonene.

As described in more detail below, only a portion of the unsubstituted DPA in the reaction mixture of step (i) is alkylated by the propylene trimer, propylene tetramer and/or propylene pentamer, commercial nonene, commercial propylene tetramer, butene trimer, or butene tetramer. Hence an amount of residual unsubstituted DPA remains in the intermediate reaction mixture formed from the alkylation in step (i).

In many embodiments, in step (ii), the unreacted first olefins are distilled from the intermediate reaction mixture. In alternative embodiments, in step (ii), the unreacted first olefins are not distilled from the intermediate reaction mixture. Rather, the first olefins remain in the intermediate reaction mixture.

In step (iii), the at least one second olefin is added to the intermediate reaction mixture and the intermediate reaction mixture is reacted in the presence of an acidic alkylation catalyst to produce a di-substituted DPA composition. The at least one second olefin is chosen from those of the formulas

styrene vinylidene Isomer 1 of vinylidene Isomer 2 of vinylidene or a-alkylstyrene where each of R’i and R’2 is independently H or straight-chain or branched C1-12 alkyl, (e.g. C4-12 alkyl) and R’₃ is H or straight-chain or branched C1-4 alkyl. Olefins of the formulas illustrated above are known and commercially available and/or may be prepared by known methods.

Often, the at least one second olefin is commercial diisobutylene, styrene, a-methylstyrene, a- alkylstyrene, 2-methyl butene-1 , 2-methyl butene-2, 2,4,4-trimethyl pentene-1 , 2,4,4-trimethyl pentene-2, or any combination thereof, e.g., manufactured by Lyondell Basell, Maruzen, or Idemitsu, and which is greater than about 95% by weight 2,4,4- trimethylpentene isomers. In many embodiments, the second olefin is diisobutylene. For example, often, at least 50% by weight, such as 60% or more, 70% or more, 80% or more, 90% or more, 95% or more, 98% or more or higher, by weight, of the second olefin is diisobutylene.

In some embodiments, the mixture of alkene isomers is propylene trimer and/or propylene tetramer, and the at least one second olefin is diisobutylene.

In some embodiments, the mixture of alkene isomers is propylene trimer and/or propylene tetramer, and the at least one second olefin is a-methylstyrene.

Excess propylene oligomer or butene oligomer present in the intermediate reaction mixture from the first alkylation reaction is often removed (such as by stripping or distillation, often under vacuum) from the intermediate reaction mixture before adding the at least one second olefin and the recovered material may be recycled for re-use in the process. Alternatively, as at least one second olefin is more reactive than the mixture of alkene isomers chosen from propylene trimer, propylene tetramer, propylene pentamer, butene trimer, butene tetramer, the process may be carried out without removing the excess propylene oligomers from the intermediate reaction mixture before adding the second olefin. Preferably, excess propylene oligomer or butene oligomer present in the intermediate reaction mixture from the first alkylation reaction is removed by distillation, which often requires vacuum, for the benefits of faster reaction, higher reactor efficiency/loading, and convenient separation and subsequent recycle of recovered excesses of both first olefin and second olefin.

Additional acid catalyst may be added to the intermediate reaction mixture for catalyzing the alkylation in step (iii). The acid catalyst from step (i) may, but need not be, removed (such as by filtration) from the intermediate reaction mixture before adding at least one second olefin. If the catalyst from step (i) is removed from the intermediate reaction mixture prior to adding the second olefin, additional acid catalyst is added to the intermediate reaction mixture to catalyze the alkylation in step (iii). The acid catalyst may be recycled for re-use in the process.

In step (iii), at least one second olefin, chosen from olefins of the formulas illustrated above, efficiently and selectively reacts with the residual unsubstituted DPA in the intermediate reaction mixture, forming the di-alkylated DPA, reducing unsubstituted DPA to less than 0.1% by weight, often less than 0.02 wt%, and reducing mono-alkylated DPAs and disubstituted DPAs with molecular weight less than 300 Daltons to less than 7 wt %, often less than 5 wt%, often less than 3 wt%, based on the total weight of unsubstituted and substituted DPAs.

Importantly, the proportion of unsubstituted DPA in the reaction mixture that is alkylated by the mixture of alkene isomers in step (i) and the extent of residual unsubstituted DPA that is alkylated by the at least one second olefin in step (iii) are controlled such that the resulting disubstituted DPA composition:

(1) contains at least 90% by weight, e.g., at least 93% by weight or at least 95% by weight, of a mixture of di-alkylated diphenylamine of formulas I, II, and III

I II III based on the total weight of unsubstituted and substituted diphenylamine in the composition, where Ri is derived from the mixture of alkene isomers and R2 is derived from the at least one second olefin, and

(2) contains less than 0.1% by weight, e.g., less than 0.02% by weight, or non- detectable by gas chromatography, of unsubstituted diphenylamine, based on the total weight of unsubstituted and substituted diphenylamine in the composition, and

(3) contains less than 7% by weight, e.g., less than 5% by weight, or less than 3% by weight, of a mixture of (a) mono-alkylated diphenylamine of formulas IV and V

where Ri derived from the mixture of the first olefin and R₂ is derived from the at least one second olefin and

(b) disubstituted DPA with molecular weight less than 300 Daltons, based on the total weight of unsubstituted and substituted diphenylamine in the composition, and

(4) contains less than 5% by weight, e.g., less than 3% by weight, or less than 1 % by weight, of a mixture of tri-alkylated diphenylamine, based on the total weight of unsubstituted and substituted diphenylamine in the composition, wherein the composition is a liquid at ambient temperature.

In particular, in step (i), the proportion of unsubstituted DPA in the reaction mixture that is alkylated by the first olefin comprising a mixture of alkene isomers of propylene oligomers and/or butene oligomers is controlled to ensure that the eventual final di-substituted DPA composition will be a liquid at ambient temperature and to limit the formation of over-alkylated DPA components, particularly tri-alkylated DPA. In this regard, a large enough proportion of unsubstituted DPA in the step (i) reaction mixture is alkylated by the mixture of the first olefin to ensure that the final disubstituted DPA composition — formed after subsequent alkylation with at least one second olefin in step (iii) — will be a liquid at ambient temperature. The proportion of unsubstituted DPA alkylated by the propylene oligomers or butene oligomers in step (i) is not so high as to result in the formation of di-alkylated DPA in reaction intermediate compositions to the extent that it would cause the end product — formed after subsequent alkylation with the second olefin in step (iii) — to have more than 5% by weight of over alkylated DPA components, particularly tri-alkylated DPA, based on the total weight of unsubstituted diphenylamine and substituted diphenylamine. In step (iii), the residual unsubstituted DPA in the intermediate reaction mixture is alkylated by the at least one second olefin such that the concentration of unsubstituted DPA in the resulting disubstituted DPA composition is less than 0.1% by weight, e.g., less than 0.02% by weight, or non- detectable by gas chromatography, based on the total weight of substituted and unsubstituted DPA in the end composition.

Often at least 60%, at least 70%, at least 80%, or at least 90% or higher of the unsubstituted DPA in the reaction mixture is alkylated by the mixture of the first olefin chosen from propylene trimer, propylene tetramer, propylene pentamer, commercial nonene, commercial propylene tetramer, butene trimer and butene tetramer. In certain embodiments, the mixture of the first olefin is propylene trimer, and the proportion of unsubstituted DPA in the reaction mixture alkylated by the propylene trimer is at least 80% or at least 90%. In certain embodiments, the mixture of the first olefin is commercial nonene, and the proportion of unsubstituted DPA in the reaction mixture alkylated by commercial nonene is at least 70%, such as at least 80%, or at least 90%. Precise lower boundaries of the proportion of unsubstituted DPA that need to be alkylated by the propylene oligomers or butene oligomers to ensure a liquid final product will vary depending on the identity of the particular mixture of the first olefin, particular second olefin, as well as on the type of catalyst and the reaction conditions, such as reaction temperature.

In general, the reaction conditions, e.g., temperature, pressure, concentrations of reaction components, and the like are similar to those used in other similar Friedel-Crafts reactions known in the art. Examples of suitable reaction conditions include, but are not limited to, those described below.

Often, the molar ratio of the mixture of the first olefin chosen from propylene trimer, propylene tetramer and propylene pentamer to the unsubstituted DPA to be alkylated in step (i) ranges from about 2.5:1 to about 3.5:1 , often from about 2.8:1 to about 3.2:1. Often, the weight ratio of the acidic alkylation catalyst to the unsubstituted DPA to be alkylated in step (i) ranges from about 0.2:1 to about 1 : 1 , often from about 0.4:1 to about 0.8:1.

Suitable reaction temperatures for the alkylation reaction of unsubstituted DPA with the mixture of the first olefin in step (i) often range from about 120 to about 170 °C, often from about 135 to about 165 °C, more often from about 145 to about 160 °C. In the suitable temperature range, acid clay has optimized reactivity towards the alkylation reaction with the first olefins and deactivates at a slower rate when compared to the deactivation rate at a temperature above 170 °C. Further, at the slower rate of deactivation of the acid clay catalyst, the catalyst may be recycled.

The process is not limited to any particular technique for preparing the reaction mixture. Reaction components may be added as a single dose or in multiple additions, metered into the reaction mixture at constant or varying rates, or by another method of addition.

The reaction of the unsubstituted DPA with the mixture of the first olefin chosen from propylene trimer, propylene tetramer, propylene pentamer, commercial nonene, commercial propylene tetramer, butene trimer and butene tetramer is allowed to proceed until the targeted proportion of unsubstituted DPA has been alkylated, as discussed above.

In the reaction step (ii), using vacuum distillation, more than 90%, e.g., more than 95 wt %, of unreacted first olefins are removed from the intermediate reaction mixture. During the distillation process, neither unsubstituted or di-substituted DPAs, is removed. The distillation may be run under vacuum at absolute pressures of 5 to 100 Torr, often 10 to 30 Torr.

In the alkylation reaction of step (iii), often the molar ratio of the at least one second olefin to the residual unsubstituted DPA and mono-substituted diphenylamine in the intermediate reaction mixture ranges from about 2: 1 to about 7:1 , often from about 3:1 to about 5: 1. The process is not limited to any particular technique for adding the at least one second olefin to the intermediate reaction mixture. The second olefin may be added as a single dose or in multiple additions, metered into the intermediate reaction mixture at constant or varying rates, or by another method of addition.

Often, the ratio by weight of the acidic alkylation catalyst to the residual unsubstituted DPA in the intermediate reaction mixture ranges from about 0.4:1 to about 1 :1 , often from about 0.6:1 to about 0.8:1.

Suitable reaction temperatures for the alkylation reaction of the residual unsubstituted DPA with the at least one second olefin in step (iii) often range from about 80 to about 150 °C, often from about 80 to about 140 °C, often from about 100 to about 140 °C, often from 115 to about 135 °C. The suitable temperature range allows the reaction mixture to have a low concentration of unsubstituted diphenylamine when the reaction reaches equilibrium. For example, a temperature range of about 80 to about 135 °C favors alkylation of diphenylamine with the second olefin to produce a low concentration of unsubstituted diphenylamine. Further, in the suitable temperature range, the acid clay may have optimized reactivity towards the alkylation reaction with the second olefin but does not catalyze the cracking of the second olefin to form smaller olefins. That is, at a temperature above 160 °C, the acid clay catalyzes the second olefin’s cracking causing the second olefin to crack into lower molecular weight molecules that have a higher reactivity toward alkylation when compared to the second olefin. For example, when diisobutylene, or other vinylidene type olefin, is used as the second olefin, it cracks at a much slower rate when compared to the rate of cracking that occurs at a temperature above 160 °C. At a temperature above 160°C, the acid clay catalyzes diisobutylene’s cracking into isobutylene. When compared to diisobutylene, isobutylene has a lower molecular weight and a higher reactivity toward alkylation. This leads to the formation of monosubstituted and disubstituted diphenylamine with molecular weights less than 300 Daltons.

The reaction of the residual unsubstituted DPA in the intermediate reaction mixture with the second olefin is allowed to proceed until the unsubstituted DPA concentration in the product is less than 0.1 % by weight, e.g., less than 0.02 wt %, or non-detected using gas chromatography, based on the total weight of substituted and unsubstituted DPA in the product composition. In addition, the reaction of the mono-substituted DPA in the intermediate reaction mixture with the second olefin is allowed to proceed until the mono-substituted DPA concentration in the product is less than 5 % by weight, e.g., less than 3 wt %, based on the total weight of substituted and unsubstituted DPA in the product composition.

The alkylation reactions of the present disclosure are not limited to any particular type of reaction vessel and may be run in an open reaction vessel, e.g., under reflux conditions, or under pressure in a sealed reaction vessel, often with a pressure less than 60 psig, e.g., less than 40 psig or less than 20 psig. The reactions may be run in the presence of an added organic solvent but are often run in the absence of an added solvent.

As discussed above, the proportion of the unsubstituted DPA alkylated by the propylene oligomer(s) relative to the proportion of residual unsubstituted DPA alkylated by the at least one second olefin may be tuned to optimize the properties and performance (particularly deposit and oxidation control) of the composition. For example, for a given reaction system of particular propylene oligomer(s) (first olefin), catalyst, and second olefin, the above described proportions may be optimized to achieve a desired liquid composition while maintaining or maximizing a high di-alkylated DPA content in the resulting di-substituted DPA composition for optimal deposit and oxidation control.

The acidic alkylation catalyst can be removed from the di-substituted DPA composition by filtration or other known separation methods. Unreacted olefins (and olefin byproducts) may be removed from the di-substituted DPA composition by known techniques, such as by stripping or distillation, often under vacuum. The temperature for distillation of olefins is usually lower than 165 °C, which can be achieved by steam heating. The unreacted first and second olefins may be recycled for re-use in the process.

The di-substituted DPA compositions of the present disclosure are useful as antioxidants, such as for lubricants and polymers. In particular, the di-substituted DPA compositions provide excellent deposit and sludge control as well as excellent antioxidant activity in lubricants, such as in industrial, marine, aviation, automotive and grease applications, in particular, such as in motor, engine, turbine, chain, gear, hydraulic, compressor and other lubricating oils and fluids, as well as in industrial and automotive grease applications.

In an alternative method of production, a process for producing an di-alkylated diphenylamine and/or alkylated, arylated di-substituted diphenylamine composition comprises reacting a reaction mixture comprising di-alkylated diphenylamine, mono-alkylated diphenylamine and less than 25 wt%, e.g., less than 20 wt%, less than 15 wt%, less than 10 wt%, of unsubstituted diphenylamine, an acid clay catalyst, and at least one olefin chosen from olefins of the following formulas

styrene vinylidene Isomer 1 of vinylidene Isomer 2 of vinylidene or a-alkylstyrene where each of R’i and R’₂ is independently H or straight-chain or branched C1-12 alkyl, (e.g. C4-12 alkyl) and R’₃ is H or straight-chain or branched C1-4 alkyl. Olefins of the formulas illustrated above are known and commercially available and/or may be prepared by known methods. The aforementioned reaction mixture is a liquid mixture derived from the reaction of unsubstituted diphenylamine or substituted diphenylamines with a mixture of alkene isomers of propylene oligomers and/or butene oligomers.

The resulting product:

I II III based on the total weight of unsubstituted and substituted diphenylamine in the composition, where R1 is derived from the mixture of alkene isomers of propylene oligomers and/or butene oligomers and R2 is derived from the at least one second olefin,

(2) contains less than 0.1% by weight, e.g., less than 0.02 wt % by weight, or non- detectable by gas chromatography, of unsubstituted diphenylamine, based on the total weight of unsubstituted and substituted diphenylamine in the composition, and

(3) contains less than 7% by weight, e.g., less than 5% by weight, or less than 3% by weight, of a mixture of

(a) mono-substituted diphenylamine of formulas IV and V

where Ri is derived from a mixture of alkene isomers of propylene oligomers and/or butene oligomers and R2 is derived from the at least one second olefin, and (b) disubstituted DPA with molecular weight less than 300 Daltons, based on the total weight of unsubstituted and substituted diphenylamine in the composition,

In many embodiments, utilizing the alternative process for producing an alkylated or arylated DPA composition, as much as 93% by weight, 95% by weight, or higher of the resulting di-substituted DPA composition, based on the total weight of unsubstituted and substituted DPA in the composition, is a mixture of di-alkylated DPA. Often, unsubstituted DPA is present in the resulting composition at less than 0.1% by weight, e.g., less than 0.02% by weight, based on the total weight of unsubstituted and substituted DPA in the composition. Typically, less than 5% by weight, e.g., less than 3% by weight or less than 1% by weight of the resulting composition, based on the total weight of unsubstituted and substituted DPA in the composition, is over-alkylated DPA, particularly tri-substituted DPA. In addition, less than 7% by weight, e.g., less than 5% by weight or less than 3% by weight of the resulting composition is disubstituted DPA with molecular weight less than 300 Daltons, based on the total weight of unsubstituted and substituted DPA in the composition, is a mixture of mono-substituted diphenylamine and disubstituted DPA with molecular weight less than 300 Daltons.

The alkylation reaction of the alternative process above is a Friedel-Crafts type reaction catalyzed by an acidic catalyst. The present disclosure is not limited to any particular type of solid acidic alkylation catalyst and a wide variety of such catalysts for Friedel-Crafts type reactions are known in the art, including mixtures of such catalysts. For example, suitable catalysts include acid clays, zeolite, phosphotungstic acid and the like. Preferably, the process uses an acid clay catalyst. Acid clay catalysts are expected to preferentially facilitate the formation of di-alkylated DPA with further advantages of producing a light colored product. Acid clay catalysts are easy to remove by decanting or filtration and may be reused many times.

Examples of suitable acid clays include acid activated clays based on bentonite, such as F-20X, F-24X, and F-25X from EP Engineered Clays, Tonsil® from Clariant, Montmorillonite K-10 , K30, APC from Sud-Chemie, Envirocat® EPZ-10, EPZG or EPIC produced by Contract Chemicals and acid activated phyllosilicates, for example those commercially available under the name Fulcat® from BYK division of ALTANA, such as Fulcat®-22 B, -22F, and -435.

In the alternative process, a reaction mixture comprises di-alkylated diphenylamine, monoalkylated diphenylamine and less than 25 wt% non-alkylated diphenylamine, an acid clay catalyst, and at least one olefin chosen from olefins of the following formulas

styrene vinylidene Isomer 1 of vinylidene Isomer 2 of vinylidene or a-alkylstyrene where each of R’i and R’₂ is independently H or straight-chain or branched C1-12 alkyl, (e.g. C4-12 alkyl) and R’₃ is H or straight-chain or branched C1.4 alkyl.

Often, the olefin used in the alternative method is the second olefin described above. For example, the olefin used in the alternative method is commercial diisobutylene, styrene, a-methylstyrene, a-alkylstyrene, 2-methyl butene-1 , 2-methyl butene-2, 2,4,4-trimethyl pentene-1 , 2,4,4-trimethyl pentene-2, or any combination thereof, or commercial grade diisobutylene that has greater than 95% by weight 2,4,4- trimethylpentene isomers. In many embodiments, the olefin is diisobutylene. For example, often, at least 50% by weight, such as 60% or more, 70% or more, 80% or more, 90% or more, 95% or more, 98% or more or higher, by weight, of the olefin is diisobutylene. In some embodiments, the olefin is a-methylstyrene.

The olefin, chosen from olefins of the formulas illustrated above, efficiently and selectively reacts with the reaction mixture comprising di-alkylated diphenylamine, mono-alkylated diphenylamine and less than 25 wt% unsubstituted diphenylamine, reducing unsubstituted DPA to less than 0.1% by weight, often, less than 0.02 wt%, and reducing mono-substituted DPA and di-substituted diphenylamine with molecular weight less than 300 Daltons to less than 5 wt %, often less than 3 wt%, based on the total weight of unsubstituted and substituted DPAs. The resulting di-substituted DPA composition:

(1) contains at least 90% by weight, e.g., at least 93% by weight, or at least 95% by weight, of a mixture of di-alkylated diphenylamine of formulas I, II, and III

I II III based on the total weight of unsubstituted and substituted diphenylamine in the composition, where Ri is derived from a mixture of alkene isomers of propylene oligomers and butene oligomers and R2 is derived from the at least one olefin,

(a) mono-substituted diphenylamine of formulas IV and V

IV V where R1 derived from a mixture of alkene isomers of propylene oligomers and/or butene oligomers and R2 is derived from the at least one olefin and

(b) disubstituted DPA with molecular weight less than 300 Daltons, based on the total weight of unsubstituted and substituted diphenylamine in the composition,

(4) contains less than 5% by weight, e.g., less than 3% by weight, or less than 1 % by weight, of a mixture of tri-substituted diphenylamine, based on the total weight of unsubstituted and substituted diphenylamine in the composition, wherein the composition is a liquid at ambient temperature.

The alternative process is not limited to any particular technique for adding the at least one olefin to the reaction mixture. The olefin may be added as a single dose or in multiple additions, metered into the intermediate reaction mixture at constant or varying rates, or by another method of addition.

Suitable reaction temperatures for the alternative alkylation reaction with the at least one olefin, according to the alternative process, often range from about 80 to about 150 °C, often from about 100 to about 140 °C, and often from 115 to about 135 °C.

The reaction of the reaction mixture with the olefin is allowed to proceed until the unsubstituted DPA concentration in the product is less than 0.1% by weight, e.g., less than 0.02 wt %, or nondetected using gas chromatography, based on the total weight of substituted and unsubstituted DPA in the product composition.

In many embodiments of the alternative method, the acidic alkylation catalyst can be removed from the di-substituted DPA composition by filtration or other known separation methods. Unreacted olefins (and olefin byproducts) may be removed from the di-substituted DPA composition by known techniques, such as by stripping or distillation, often under vacuum. The unreacted olefins may be recycled for re-use in the process. The di-substituted DPA compositions of the present disclosure are useful as antioxidants, such as for lubricants and polymers. In particular, the di-substituted DPA compositions provide excellent deposit and sludge control as well as excellent antioxidant activity in lubricants, such as in industrial, marine, aviation, automotive and grease applications, in particular, such as in motor, engine, turbine, chain, gear, hydraulic, compressor and other lubricating oils and fluids, as well as in industrial and automotive grease applications.

In many embodiments, a lubricating oil composition comprises (A) a lubricating oil and (B) a di- substituted DPA composition of the present disclosure in an amount effective to provide antioxidative activity. The lubricating oil may be any lubricating oil, natural, synthetic or mixtures thereof, of lubricating viscosity suitable for the intended application, and a wide range of lubricating oils is known in the art. In many embodiments, the lubricating oil is a majority component, i.e., present in more than 50% by weight based on the weight of the lubricating oil composition, for example, 60% by weight or more, 70% by weight or more, 80% by weight or more, 90% by weight or more, 95% by weight or more, or 98% by weight or more.

In many embodiments, the presently disclosed di-substituted DPA compositions are present in the lubricating oil composition at from about 0.1 to about 10% by weight, based on the total weight of the lubricating oil composition, often from about 0.2 to about 5% by weight, from about 0.2 to about 3% by weight, or from about 0.5 to 2% by weight.

The lubricating oil composition may include any number of other additives commonly used in such compositions, such as dispersants, detergents, corrosion/rust inhibitors, other antioxidants, antiwear agents, antifoaming agents, friction modifiers, seal swell agents, emulsifiers, VI improvers, pour point depressants, and others. The types and uses of these additives are known, such as described in US Patent Publication No. 2019/01277656, which is incorporated herein by reference for its disclosure of such additional additives useful in the formulation of lubricating oil compositions.

In general, the lubricating oil compositions typically contain additives in a collective concentration ranging from about 0.2 to about 30% by weight, e.g., from about 0.2 to about 20% by weight, from about 0.2 to about 15% by weight, from about 0.5 to about 10% by weight, or from about 0.5 to about 5% by weight. EXAMPLES

Analytical Procedures

Gas Chromatography:

Product compositions and the compositions of reaction mixtures that were sampled from the reactor during the reaction were analyzed by capillary column gas chromatography to determine their chemical composition. The weight percentages shown in the Tables below for the unsubstituted and di-substituted DPA components are based on the total weight of unsubstituted and substituted DPA in the respective compositions.

Instrument: Agilent 7890 or Hewlett Packard 6890

Injector Technique: Cool on Column

Injection Volume: 0.5 pl

Column: DB 5MS or equivalent, 15 m, 0.53 mm

Detector: FID

Integration: 1.5 to 27 min

Carrier Gas: He (6.0 ml/min)

Auxiliary gases: H₂ (40 ml/min); Air (400 ml/min)

Temperature

Injector: 3 min at 50 °C, 50 °C / min up to 290 °C, 19.2 min at 290 °C

Oven: 1 min at 40 ⁰ C, 25 °C I min up to 200 °C;

10 °C / min up to 320 °C, 7.6 min at 320 °C

Detector: 330 °C

Duration: 27 min

Sample preparation: 50 mg in 5 ml acetone

Performance Tests:

Resistance to oil oxidation was measured per ASTM D6186 pressure differential scanning calorimetry (PDSC) at 180 °C. Oxidation induction time was reported in minutes. Deposit formation was measured per ASTM D7097 thermo-oxidation engine oil simulation test (TEOST).

Comparative Example 1 Comparative Example 1 simulated the procedure of experimental example 6 in US Patent No. 9,890,346.

A dry and clean 300 ml Parr reactor was charged with 50 grams (0.30 moles, 50 ml) DPA and 5 grams AICI3 powder (0.037 moles, 2 ml, Aldrich). The reactor was sealed, pressurized with N₂ at a pressure 50 psig and vented three times. The reactor was then heated to about 184 °C in about 1 hour. 75.5 grams ( 1.51 moles, 98 ml) of propylene tetramer (first olefin) was then loaded to the reactor through a FMI precision pump over 4 hours and the reaction was held at 185 ± 1 °C for 2.5 hours. Cooled to a temperature of 140 °C, and 51 grams diisobutylene (0.45 moles, 71 ml) as second olefin was added in three parts over 4 hours. The reaction was agitated and held at 140 ± 1 °C for additional 3 hours. The reaction mixture was worked up according to a standard water washing procedure to remove the catalyst. 142 grams crude reaction product in tan color was obtained.

The crude reaction product was stripped under 10 to 15 torr in a distillation head temperature range between 120 and 190 °C. 29 grams colorless distillate was obtained. 113 grams brown viscous liquid was obtained as finished product after olefins were mostly removed. The product mixture was continued to be distillated under 1.7 to 2.2 torr in a distillation head temperature range between 200 and 258 °C until 92.5 grams composition of mixture in the pot contained less than 5% by weight of mono-substituted diphenylamine. 17.3 grams distillate in tan color was obtained. The composition of samples obtained were analyzed separately by gas chromatography. The weights and compositions of crude reaction mixture, finished products in pot and distillates are shown in Table 1 below.

Table 1

The results indicate that disubstituted DPA was achieved in 95% assay by distilling out greater than 17% by weight materials (e.g. DPA and certain substituted DPAs distillate) at temperature greater than 200 °C and high vacuum (lower than 1 Torr) from crude product with olefin already stripped. The distillate shown in Table 1 comprised unsubstituted diphenylamine, monosubstituted diphenylamine and di-substituted diphenylamine with relatively low molecular weight. The distillation techniques of Comparative Example 1 are expensive and have the disadvantages of high energy consumption, high carbon emission and high amount of material loss.

Comparative Example 2

Comparative Example 2 simulated the procedure of experimental example 4 disclosed in US Patent No. 9,890,346.

Three 100 ml 3-neck flasks (A, B, C) were mounted on a parallel workstation that had synchronized overhead agitation and heating. At room temperature, reactor A was loaded with 22 g Naugalube® 438L (NL 438L), 2.2 g anhydrous AlCh, and 14.8 g nonenes (2.9 eq.). At room temperature, reactor B was loaded with 23 g NL 438L and 2.3 g anhydrous AICI3. At room temperature, Reactor C was loaded with 31 g NL 438L and 3 g Fitrol® 20X, which was pre-dried by removing about 9 wt% water. Reactors A, B, and C were heated to 130 °C under agitation. The reactors were held under 130±5 °C for 30 mins. Aliquots from reactors were taken and the samples were worked up by using approportionate CH2CI2 and H₂O to extract the organic mixture into CH2CI2, and then gas chromatography was conducted for composition analysis. The composition of Naugalube® 438L starting material that was used to run three parallel reactions and in-process sample compositions from the three reactors A, B, C were determined by gas chromatography and the results are shown in Table 2 below.

Table 2

As shown in Table 2, using aluminum chloride as a catalyst (reactor B) resulted in dealkylation of substituted DPA in the reaction mixture. However, using an acid clay as a catalyst (reactor C), dealkylation is negligible. Using aluminum chloride as a catalyst (reactor A) and heating Naugalube® 438L in the presence of nonenes inhibited de-alkylation of DPA but generated excessive tri-alkylated DPAs through nonylation.

Further, as shown in Table 2, in the presence of metal halide catalyst, AICI3, and in absence of nonenes, about 5% Naugalube® 438L underwent de-alkylation during heating to 130 °C. Dealkylation was shown by the increase of DPA, mono-nonylated DPA, and nonenes’ percentages by weight based on the total weight of reaction mixture. However, in the presence of acid clay, for example, Filtrol 20X, and in the absence of nonenes, only about 0.3% Naugalube® 438L underwent de-alkylation. In the same comparative experiment, Naugalube® 438L in the presence of AICI3 was heated in the presence of nonenes. The reaction showed Naugalube® 438L continued to react with nonenes, which led to the increase in the amount of tri-nonylated diphenylamines from 6.9% to 10.5 wt%. Therefore, if the amount of the first olefin is not controlled properly, there is an excessive amount of over alkylated DPA formed by an undesired reaction of DPA with first olefin in the presence of second olefin. As such, when using commercial acid activated clay as catalyst, there are less olefin and other organic waste generated, reactor efficiency is improved, yield and product quality are both improved.

Examples 1 to 3 - General synthesis method

Inventive Example 1

A dry and clean 300 ml Parr reactor was charged with 55.7 grams (0.33 moles, 48 ml) DPA and 28.8 grams pre-dried acid clay Filtrol® 20X (EP Engineered Clays). The reactor was sealed, pressurized with N₂ at a pressure 50 psig and vented three times. The reactor was then heated to about 155 °C in 40 min. 116 grams (0.92 moles, 156 ml) of nonenes (first olefin) was then loaded to the reactor and the reaction was held at 155 °C for 6.5 hours. A distillation column, condenser, and vacuum pump was attached to the Parr reactor. A vacuum was applied to remove most unreacted nonenes (e.g. 56 gram) by distillation over 1 hour. After the removal of the first olefin, the final vacuum was about 20 torr. The reactor was then cooled to a temperature of 125 °C, after which 84 grams (0.75 mole, 117 ml) diisobutylene (second olefin) was added to the reactor over 20 min. The reaction was held with diisobutylene at 125 °C for 10 hours after which the reaction was stopped by stopping heating and agitation. A 300 ml pressure filter was used to filter the crude reaction mixture at 80 °C and under N₂ at a pressure of 50 psig. The clear, colorless filtrate was stripped under vacuum at 10 torr and temperature up to 160 °C to remove unreacted olefins. A transparent, light tan, viscous liquid (113 g) was obtained without further purification.

The product composition was determined by gas chromatography, and the chemical formula and structure was determined by high resolution mass spectroscopy and the results are shown in Table 3 below.

Table 3

As described above and shown in Table 3, composition of the end product produced according to Example 1 produced a liquid product at ambient temperature with high di-alkyl DPA content (93 wt%), low tri-alkyl DPA content (0.3 wt%), and low unsubstituted DPA content (less than 0.02 wt%).

A sample of the reaction mixture (produced according to Example 1) prior to nonenes distillation was taken and its composition was determined by gas chromatography. The results are shown in Table 4 below.

Table 4

As shown in Table 4, the composition of a reaction mixture after the reaction of the first olefin is 5.6 wt% unsubstituted DPA, and even higher (7.3 wt%) when clay and nonenes are excluded, indicating that the composition may undergo an additional reaction with the second olefin in order for the final product composition to have less than 0.1 wt% unsubstituted DPA, based on the total weight of substituted and unsubstituted DPA.

Inventive Example 2

A dry and clean 300 ml Parr reactor was charged with 50 g (0.30 moles, 43 ml) DPA and 30 g pre-dried acid clay Filtrol® 20X (EP Engineered Clays). The reactor was sealed, pressurized with N₂ at pressure 50 psig and vented three times. The reactor was then heated to about 130 °C in 50 min, and 122 g ( 0.725 moles, 158 ml) propylene tetramer were added to the reactor over 5 min. The reactor continued to be heated for 20 minutes until the reactor temperature reached 155 °C. The reaction was held at 155 °C for 6 hours. A distillation column, condenser and vacuum pump were attached. Vacuum was applied at 155 °C to remove most unreacted propylene tetramer over about 1 hour. The final vacuum was about 20 torr. Under agitation and maintaining reactor temperature at 155 °C, 80 g ( 0.48 moles, 108 ml) propylene tetramer were added over 20 min. Reaction was held for 165 min, after which propylene tetramer distillation was repeated in a temperature range of 155 °to 140 °C under vacuum. After most propylene tetramer was removed, reactor was cooled to a temperature of about 125 °C, and 80 g (0.714 mole, 111 ml) diisobutylene were added to the reactor over 35 min. The reaction was held at 125 °C for 8 hours and then the reaction was stopped by stopping heating and agitation. A 300 ml pressure filter was used to filter the crude reaction mixture at 80 °C and under N₂ at a pressure of 50 psig. The clear, colorless filtrate was stripped under vacuum 10 at torr and temperature up to 160 °C to remove unreacted olefins. A light tan, viscous liquid (120 grams) was obtained.

The product composition was determined by gas chromatography. The analysis showed that the finished product’s composition contained 1.4 wt% diisobutylene dimers, less than 0.02 wt% unsubstituted DPA, 0.2 wt% mono-alkylated DPA, 96.5 wt% di-alkylated DPAs, and 1.7 wt% trialkylated DPA, based on the total weight of product.

Inventive Example 3

A dry and clean 300 ml Parr reactor was charged with 50.2 grams (0.30 moles, 43 ml) DPA, 25.5 g pre-dried Filtrol 20X, and 33 g (0.26 moles, 44.6 ml) nonenes (propylene trimer). The reactor was sealed, pressurized with N₂ at a pressure 50 psig and vented three time. The reactor was then heated to about 155 °C in about 80 min, and 94.1 g ( 0.75 moles, 127.2 ml) nonenes were added to the reactor at a rate of 1.1 gram per minute. The reaction was held at 155 °C for 7.4 hours. Distillation column, condenser, and vacuum pump were attached and vacuum was applied to remove most unreacted nonenes (47.2 g) by distillation over 1 hour. The final vacuum was about 20 torr. Reactor was cooled to a temperature of 130 °C, and then 27 g (0.22 mole, 30 ml) a-methylstyrene were added to the reactor over 180 min. Reaction with a-methylstyrene was held at 120 °C for about one hour and then the reaction was stopped by turning off heating and agitation. A 300 ml pressure filter was used to filter the crude reaction mixture at 80 °C and under N₂ at a pressure of 50 psig. The clear, colorless filtrate was stripped under vacuum at 10 torr and temperature up to 180 °C to remove unreacted olefins. A light tan, viscous liquid (111 g) was obtained.

The product composition was determined by gas chromatography. The analysis showed that the finished product’s composition contained about 10 wt% a-methylstyrene dimer and trimers, diisobutylene dimers, less than 0.02 wt% unsubstituted DPA, 0.7 wt% mono-alkylated and mono- arylated DPA, 95 wt% alkylated, alkylated di-substituted DPA, and 5.5 wt% tri-substituted DPA.

Inventive Example 4 (Alternative production method)

A Dean-Stark trap filled with toluene was attached to a one liter resin kettle reactor, 291 grams Naugalube® 438L (containing about 0.5 wt% of unsubstituited diphenylamine, 20 wt% mono- nonylated diphenylamine), 185 grams toluene and 30 grams Filtrol 20X were loaded to the resin kettle. The reactor was heated to 120 °C, and then 25 grams a-methylstyrene was loaded via a drop-wise addition funnel in approximately one hour at 120°C. The reaction was then post-reacted at 120°C for two hours. The reaction mixture was filtered to remove Filtrol 20X catalyst and then stripped at 150 °C and under 20 torr vacuum for one hour. 283 grams of a tan, viscous liquid product was obtained.

Gas chromatography analysis showed that the finished product’s composition contains nonenes dimer 0.3%, a-methylstyrene dimers 1.42%, DPA <0.02%, total mono-alkylated DPA 4.5%, total di-alkylated DPAs about 93%, total tri-alkylated DPA about 1 %.

The di-substituted DPA products of Inventive Examples 1 and 2 were formulated into lubricating oils and tested for their performance in inhibiting oxidation induction activity using pressure differential scanning calorimetry (PDSC) techniques and deposit formation was measured using thermo-oxidation engine oil simulation test (TEOST). The results are illustrated in Table 5 below.

Table 5. Antioxidative and Deposit Control Properties of Liquid di-substituted DPA Composition

The TEOST data is in mg of deposits, a lower value means less deposits, and the PDSC data is in minutes until onset of oxidation, a higher value represents greater protection. The deposit formation measure in TEOST indicates that compositions with higher wt% dialkylated DPA have better performance than compositions with lower wt% dialkylated DPA. Compositions of Examples 1 and 2 were prepared by the inventive process disclosed herein. Both compositions are stable in liquid and demonstrate better deposit control when compared to commercial liquid alkylated DPA, e.g. Naugalube® 438L. Further, the oxidation induction time measured in the PDSC test indicates that compositions with higher wt% monoalkylated DPA have better performance than compositions with lower wt% monoalkylated DPA. Compositions of Examples 1 and 2 were prepared by the inventive process disclosed herein. Both compositions are stable liquids and demonstrate equivalent performance to commercial liquid alkylated DPA, e.g. Naugalube® 438L, even though the content of the more active antioxidant monoalkylated DPA is lower by about 15% by weight in Example 1 and about 18% by weight in Example 2.

Table 6. Modelled LogKow, water solubility and toxicokinetic parameters of the different constituents of two commercial substituted diphenylamine antioxidants.

Source: Case study on the use of integrated approaches for testing and assessment for repeat dose toxicity of substituted diphenylamines (SDPA). OECD Series on Testing & Assessment, No. 252. ENV/JM/MCNO(2016)50.

Table 6 above discloses modelled LogKow, water solubility and toxicokinetic parameters of the different constituents of two families of commercial substituted diphenylamine antioxidants. Each of the products was modelled using an oral dose of 5 mg/kg body weight 70 kg human) with Perceptra PK Explorer. In general, constituents with molecular weights exceeding 300 Daltons tend to exhibit lower toxicity levels. They also typically have lower oral bioavailability, reduced AUG values, lower water solubility, and higher LogKow values compared to constituents with higher toxicity levels. For example, monobutyl DPA, dibutyl DPA, and monooctyl DPA, had higher oral bioavailability, higher AUG (area under curve) values, and lower LogKow values when compared to constituents with molecular weight above 300 Daltons. Further, as shown in Table 5, monononyl DPA, which is mono substituted DPA, had a molecular weight below 300 Daltons, whereas dinonyl DPA, which is disubstituted DPA, had a molecular weight above 300 Daltons.

Although particular embodiments of the present invention, including those in the particular examples above, have been described, they are not meant to be construed in a limiting sense. As will be apparent to those skilled in this art from the above specification, variations may be made without departing from the principle and scope of the present invention, which is defined by the appended claims.

Claims

What is Claimed is:

1 . An efficient, low energy consuming, low hazardous waste process of producing a safe and environmentally-friendly di-alkylated diphenylamine and/or alkylated, arylated di-substituted diphenylamine composition, comprising:

(i) reacting a reaction mixture comprising unsubstituted diphenylamine, a first olefin comprising a mixture of alkene isomers chosen from propylene and butene oligomers, and an acid clay catalyst to form an intermediate reaction mixture comprising an isomeric mixture of disubstituted diphenylamine of formula I,

i mono-substituted diphenylamine of formula IV,

and residual unsubstituted diphenylamine, wherein Ri is derived from the mixture of alkene isomers, and

(iii) adding at least one second olefin chosen from olefins of formulas

styrene vinylidene Isomer 1 of vinylidene Isomer 2 of vinylidene or a-alkylstyrene where each of R’i and R’2 is independently H or straight-chain or branched C1-12 alkyl, (e.g. C4-12 alkyl) and R’₃ is H or straight-chain or branched C1-4 alkyl, to the intermediate reaction mixture, and reacting the intermediate reaction mixture in the presence of an acidic alkylation catalyst to produce the di-alkylated diphenylamine and/or alkylated, arylated di-substituted diphenylamine composition, wherein the proportion in the reaction mixture that is alkylated by the mixture of the first olefin in step (i) and the extent of residual unsubstituted diphenylamine that is alkylated by the second olefin in step (iii) are controlled such that the resulting di-alkylated diphenylamine and/or alkylated, arylated di-substituted diphenylamine composition comprises:

(1) at least 90% by weight of a mixture of di-alkylated diphenylamine of formulas I, II and III

I II III in various ratios, based on the total weight of unsubstituted and substituted diphenylamine in the composition, wherein R1 is derived from the mixture of the first olefin and R₂ is derived from the at least one second olefin,

(3) less than 7% by weight of a mixture of

(a) mono-alkylated diphenylamine of formulas IV and V

wherein R1 derived from the mixture of the first olefin and R₂ is derived from the at least one second olefin and (b) di-substituted diphenylamine with molecular weight less than 300 Daltons, based on the total weight of unsubstituted and substituted diphenylamine in the composition, and (4) less than 5% by weight of a mixture of tri-substituted diphenylamine, based on the total weight of unsubstituted and substituted diphenylamine in the composition, wherein the composition is a liquid at ambient temperature.

2. The process of claim 1 , wherein the resulting di-alkylated diphenylamine and/or alkylated, arylated di-substituted diphenylamine composition contains at least 95% by weight, based on the total weight of unsubstituted and di-substituted diphenylamine in the composition, of a mixture of di-substituted diphenylamine of formula I, II and III.

3. The process of claim 1 , wherein at least 70% by weight, preferably at least 80% by weight, of the mixture of di-alkylated diphenylamine comprises para, para’ di-substituted diphenylamine.

4. The process of claim 1 , wherein the resulting di-alkylated diphenylamine and/or alkylated, arylated di-substituted diphenylamine composition contains less than 0.02% by weight, based on the total weight of unsubstituted and substituted diphenylamine in the composition, of unsubstituted diphenylamine.

5. The process of claim 1 , wherein the resulting di-alkylated diphenylamine and/or alkylated, arylated di-substituted diphenylamine composition contains less than 5% by weight of a mixture of mono-substituted diphenylamine and di-substituted diphenylamine with molecular weight less than 300 Daltons, based on the total weight of unsubstituted and substituted diphenylamine in the composition.

6. The process of claim 1 , wherein the resulting di-alkylated diphenylamine and/or alkylated, arylated di-substituted diphenylamine composition contains less than 3% by weight of a mixture of tri-substituted diphenylamine, based on the total weight of unsubstituted and substituted diphenylamine in the composition.

7. The process of claim 1 , wherein the at least one second olefin is chosen from diisobutylene, styrene, a-methylstyrene, a-alkylstyrene, 2-methyl butene-1 , 2-methyl butene-2, 2,4,4-trimethyl pentene-1 , 2,4,4-trimethyl pentene-2, or commercial diisobutylene.

8. The process of any one of claims 1-7, wherein in each of steps (i) and (iii) the acidic alkylation catalyst is an acid clay catalyst.

9. The process of any one of claims 1-7, wherein in the step (i) the reaction mixture is reacted at a temperature range from about 120 to about 170 °C, often from about 135 to about 165 °C, more often from about 145 to about 160 °C.

10. The process of any one of claims 1-7, wherein in the step (iii) the reaction mixture is reacted at a temperature range from about 80 to about 150 °C, often from about 100 to about 140 °C, often from 115 to about 135 °C.

11. An efficient, low energy consuming, low hazardous waste process of manufacturing safe and environmental-friendly di-alkylated diphenylamine and/or alkylated, arylated di-substituted diphenylamine compositions, comprising: reacting a reaction mixture comprising di-alkylated diphenylamine, mono-alkylated diphenylamine and less than 25 wt% unsubstituted diphenylamine, an acid clay catalyst, and at least one olefin chosen from olefins of formulas

styrene vinylidene Isomer 1 of vinylidene Isomer 2 of vinylidene or a-alkylstyrene where each of R’i and R’2 is independently H or straight-chain or branched C1-12 alkyl, (e.g. C4-12 alkyl) and R’₃ is H or straight-chain or branched C1-4 alkyl, to produce a di-alkylated diphenylamine and/or alkylated, arylated di-substituted diphenylamine composition, wherein the resulting di-alkylated diphenylamine and/or alkylated, arylated di-substituted diphenylamine composition comprises:

I II III in various ratios, based on the total weight of unsubstituted and substituted diphenylamine in the composition, wherein Ri is derived from a mixture of alkene isomers of propylene oligomers and/or butene oligomers and R₂ is derived from the at least one olefin,

(2) less than 0.1% by weight of unsubstituted diphenylamine, based on the total weight of unsubstituted and substituted diphenylamine in the composition, and

(3) less than 7% by weight of a mixture of

(a) mono-substituted diphenylamine of formulas IV and V

wherein Ri is derived from the mixture of the first olefin and R₂ is derived from the at least one olefin and

(b) di-substituted diphenylamine with molecular weight less than 300 Daltons, based on the total weight of unsubstituted and substituted diphenylamine in the composition,

(4) less than 5% by weight of a mixture of tri-substituted diphenylamine, based on the total weight of unsubstituted and substituted diphenylamine in the composition, wherein the composition is a liquid at ambient temperature.

12. The process of claim 11 , wherein the resulting di-alkylated diphenylamine and/or alkylated, arylated di-substituted diphenylamine composition contains at least 95% by weight based on the total weight of unsubstituted and di-substituted diphenylamine in the composition, of a mixture of di-substituted diphenylamine.

13. The process of claim 11 , wherein at least 70% by weight preferably at least 80% by weight, of the mixture of di-alkylated diphenylamine comprises para, para’ di-substituted diphenylamine.

14. The process of claim 11 , wherein the resulting di-alkylated diphenylamine and/or alkylated, arylated di-substituted diphenylamine composition contains less than 0.02% by weight, based on the total weight of unsubstituted and substituted diphenylamine in the composition, of unsubstituted diphenylamine.

15. The process of claim 11 , wherein the resulting di-alkylated diphenylamine and/or alkylated, arylated di-substituted diphenylamine composition contains less than 5% by weight of a mixture of mono-substituted diphenylamine and di-substituted diphenylamine with molecular weight less than 300 Daltons, based on the total weight of unsubstituted and substituted diphenylamine in the composition.

16. The process of claim 11 , wherein the resulting di-alkylated diphenylamine and/or alkylated, arylated di-substituted diphenylamine composition contains less than 3% by weight of a mixture of tri-substituted diphenylamine, based on the total weight of unsubstituted and substituted diphenylamine in the composition.

17. The process of claim 11 , wherein the at least one olefin is chosen from diisobutylene, styrene, a-methylstyrene, a-alkylstyrene, 2-methyl butene-1 , 2-methyl butene-2, 2,4,4-trimethyl pentene-1 , 2,4,4-trimethyl pentene-2, or commercial diisobutylene.

18. The process of any one of claims 11-17 wherein the acidic alkylation catalyst is an acid clay catalyst.

19. The process of any one of claims 11-18, wherein in the reaction mixture is reacted at a temperature range from about 80 to about 150 °C, often from about 100 to about 140 °C, often from 115 to about 135 °C.

20. A lubricating oil composition comprising (A) a lubricating oil and (B) a di-alkylated diphenylamine and/or alkylated, arylated di-substituted diphenylamine composition prepared according to the process of claims 1 or 11 in an amount effective to provide antioxidant activity.

21. The lubricating oil composition of claim 20, wherein the di-alkylated diphenylamine and/or alkylated, arylated di-substituted diphenylamine composition is present in the lubricating oil composition at from about 0.1 to about 10 wt%, based on the total weight of the lubricating oil composition.

22. Use of a di-alkylated diphenylamine and/or alkylated, arylated di-substituted diphenylamine composition produced by the process according to claims 1 or 11 in a lubricating oil composition in an amount effective to provide antioxidative activity and to reduce and/or prevent toxicity of the lubricating oil composition.