US2435333A - Soap compositions - Google Patents

Description

Patented Feb. 3, 1948 SOAP oomosI'rIoNs Ellis R. White, Albany, Calif., assignor to Shell Development Company, San Francisco, Calif., a corporation of Delaware No Drawing. Application November 15, 1943, 7

Serial No. 510,428

11 Claims. (01. 260-3985) This invention relates to relatively high molecular weight (non-gaseous) unsaturated fatty acids and their salts and esters 'such asare present in soap, oils, greases; waxes, and the like, which unsaturatedorganic constituents are stabilized against oxidative "decomposition by one or more of the non-gaseous aromatic amino carboxylic compounds of the present specification. It also relates to improved greases such as those containing a lubricating oilbase which i rendered plastic by the addition of a suitable metallic soap which is'inhibited against deterioration by an aromatic amino carboxylic compound of the instant invention. 7

It has been suggested heretofore to stabilize organic compositions by the addition of unsaturated organic compounds which are themselves 7 easily oxidized, thereby preventing the oxygen from attacking the composition which -one is seeking to inhibit.

However, I have now found that compositions containing relatively high molecular weight unsaturated carboxyllc compounds (i. e. having a minimum of about 10 carbon atoms) may be protected against oxidative attack by the incorporation of a soluble aromatic amino, saturated organic compound containing a radical. The free bond of this oxygen atom may be attached toa hydrogen atom, a metallic atom or an organic radical thus yieldingfrespectively a carboxylic acid (RCO'OHL a carboxylic acid salt (RCOOM, RCOOMOI-I, (RQOO) 2M, etc., depending on the valence of the metal) and a carboxylic acid ester (RCOOR) These three types of compounds are referred to throughout this specification and claimsas carboxylic compounds. The term saturated compound is. used to designate compounds free of oleflnic or acetylenic linkages and-is not intended to exclude compounds containing aromatic nucleii which compounds, as is well known, react as saturated compounds,

A fundamental requirement of my additives is that they be substantially miscible or soluble in the carboxylic composition to be stabilized. Thus, to be oil-solublethe should usually have a minimum of about 12, more preferably 16 or 20, carbon atoms. More advantageously these carbon 7' atoms are present in a saturated aliphatic chain which is attached to the aromatic amino group. Thus the aromatic amino compounds of saturated fatty acids, salts and esters having a minimum 1 of about l lcarbon atoms constitute a preferred group of my additives.

This is not to say, however, that aromatic amino saturated fatty acids possessing less than such minimum numbers of carbon atoms would not'possess oxidation inhibiting effect but rather than those which were not oil soluble would be unsatisfactorily incorporated throughout the oily medium and also those which were water soluble would be leached out of the soap or other substancewhen it came in contact with water. My

inhibitors also should preferably be free of polar radicalssuch as OH, SH N02, P04, halogen, etc. 'Thea'ction'of my inhibitors is specific to carboxylic compositions containing unsaturated organic radicals of relatively high molecular weight, that is, having at least about 10 carbon atoms per molecule as previously stated. In organic compositions which may contain saturated carboxylic compounds such as refined lubricating oils which have been treated to remove unsaturated components, my inhibitors are without effect. Likewise m compounds are not adapted as inhibitors for gasoline, particularly cracked gasoline which contains a considerable amount of low molecular weight olefins.

My aromatic amino fatty acid compounds are,

which are mixtures of higher molecular weight.

saturated and unsaturated fatty acid compounds.

Since the unsaturated compounds to be stabilized are often found in soap in the form of their metallic salts, the corresponding metallic salts of my inhibitors may be used rather than the free saturated aliphatic, amino aromatic compound. Thus, for example, oleic acid may be stabilized by my aromatic amino stearic acid; sodium or aluminum oleate may be stabilized by the addition of sodium or aluminum aromatic amino stearate respectively. However, the inhibitor need not contain the same metallic radical as the unsaturated soap but there is generally no advantage of adding an inhibitor of a different metal as the metallic ions will interchange in solution. Also, it is generally undesirable to have much free acid present in a soap or grease; particularly in the case of grease, it may tend to cause phase separation.

In my inhibitors the aromatic amino group may advantageously be attached to the carbon atom which is in alpha position to the carboxyl carbon atom. These compounds may be'represented by' the formula:

is one, two orthree, and y is 'two, one,-'or zero, 'etc.

' The aromatic'radical R1 may'als'obe substituted by other amino groups, by hydroxy and/or by hydrocarbon radicals; Such hydrocarbon radicals as well as the other "hydrocarbon radicals represented by the Rs of the formula maybe exemplified'by methyl. ethyl, propyl. cyclopropyl, butyl,

cyclobutyl, pentyl, cyclopentyl, hexyl, :cyclohexyl, heptyL-octy'l, nonyl, decyl, deca'lin and the like. Ri'isprferabl y a fatty acid-radical but it may also consist of or contain one or more aromatic radicals.

Among the fatty-acid radicals adapted for employment in my aromaticam'ino -'carboxylic acid inhibitor, particular mention may be made of lauric, tridecylic, myristic, 'pentadecylic, palmitic, margaric, stearic, thapsic, undecylic, arachidic, heneicosoic, eicosane cafboxylic, chrytin-ic, behe'nic, tricosoic, lignocenic, pentacosoic, cerotic, hexacosoic, carbocenic, octacosoi'c, montanic, 'melissic, myricinic, psyllaic, psyllostear'icand the like.

As may be seen from the above formula, the amine radical may be secondary or tertiary. Among the acids meeting the above requirements are several which are particularly useful, e. g., an'ilino, toluidino, methyl anilino, etc., fatty acids, naphthenic acids or parafiin carboxylic acids totaling 22 or morecarbon atoms and wherein the fatty acid chain containsat'least 14 carbon atoms. of particular utility are, e. g., alpha (ortho toluidino) stearic acid 4 Thus acids of the following formulae are among those preferred:

' V '4 RI nuclear, and R2 ;is hydrogen ora hydrocarbon radical. The A radicals are hydrogen, hydroxy,

primary'amino, oralkyl radicals (such asare .con-

-, tained in naphthenic acids naturallyoccurringin petroleum. oils), Among the useful amino radicals are thefollowing:

Incompounds in "which A is a hydroxy or an amino group, 'theselatter are preferably'ortho or para to "the iirst amino radical and such amino radical or radicals 'shouldgprefera'bly be primary or secondary amines. I

An alpha-aromatic amino monocarboxylic acid may be produced, for example, by starting with toluidino acetic acid and reacting it with a suitablealkyl halide containing, say, 16 or more carbon atoms such as chlorinatedparaflinwax, etc. Another method Iior producing alpha-aromatic amino monocarboxylic acids comprises halogenating aliphatic carboxylic acids under conditions to introduce at least one halogen atom in alpha position to the carboxyl radical. This may be accomplished by the Hell Volkard .Zelinsky reaction (see Meyer and Jacobson, vol. 1, part 2, page 479) whereby an alpha halo acid halide is pro-- duced. product is then hydrolyzed .to liberate the alpha'halo carboxylic acid. This acid is then simplyiheatedaif necessary under pressure, with an aromatic amine. .The free alpha-aromatic amino monocarboxylic acid is then converted to the metal salt-by any conventional method. Thus, it maybe directly reacted with a metallic oxide or hydroxide, or its alkali metal salt may first bejformed which is then doubledecomposed with a-suita'bie metallic salt.

The following examples'serve to further illustrate my invention:

Example I Stearic acid was brominated by the Hell Volkard Zelinsky reaction under conditions to in sure complete conversion of all the stearicacid to the corresponding alpha bromo acid bromide. The resulting product was hydrolyzed with warm water, and the bromo acid thereby obtained was dried by solution in isopentane and subsequent crystallization. The alpha bromo stearic acid, which had a melting point of 60 C., was then heated with two equivalents of o-toluidinefor one hour at *120-150 C. At this point, all of the bromide was determinable with silver nitrate.

The product was cooled, filtered from toluidino hydrobrcmide and crystallized from glacial acetic acid.

The above product was mixed with oleic acid and then reacted with ammonium hydroxide in alcohol solution to form the ammonium salt. The alcohol solution of this salt was then mixed with an alcohol solution of aluminum chloride, the mol ratio of acid to aluminum. being 2 to 1. One percent of this aluminum salt of alpha ortho toluidino stearic acid increased the oxidation induction period of the aluminum oleate from 20 minutes (uninhibited) to 500 minutes.

Example II One percent of the aluminum salt of alpha ortho toluidino stearicacid increased the oxidation induction period of aluminum tall oil soap (trade name Bogol) from minutes (uninhibited) to 600 minutes.

Example III One half percent of the aluminum salt of alpha (anilino para amino) stearic acid increased the oxidation induction period of aluminum oleate from 20 minutes (uninhibited) to 186 minutes.

Example IV 0.05% of the aluminum salt of alpha (anilido para hydroxy) stearic acid increased the induction period of aluminum oleate from 21 minutes (uninhibited) to 300 minutes.

In general, amounts of my inhibitor between about 0.05% w. and 5% w. will be sufficient to stabilize a liquid composition of the type defined. Lubricating greases are usually composed of about 5% to 50% metallic soap in mineral lubricating oil. In such compositions my inhibitor may be present in aliquot amount, based on the proportions indicated above. Of course, the inhibitor concentration may be made up from a mixture of two or more of the inhibitors of the present invention, rather than utilizing a single compound. Likewise, part of the inhibitor may be present as a metallic or non-metallic salt or ester while the other part is present as the free acid. Various modifications will suggest themselves to those skilled in the art, the specific examples and exact proportions used to illustrate the invention herein, not being intended as limitations.

I claim as my invention:

1. An aluminum soap of an unsaturated fatty acid compound stabilized against oxidative decomposition by about 0.05%-5% of aluminum salt of alpha (ortho toluidino) stearic acid.

2. An aluminum soap of an'unsaturated fatty acid compound stabilized against oxidative decomposition by about 0.05%5% of aluminum salt of alpha (anilino para amino) stearic acid.

3. An aluminum soap of an unsaturated fatty acid compound stabilized against oxidative decomposition by about 0.05%-5% of aluminum salt of alpha (anilino para hydroxy) stearic acid.

4. An organic composition comprising as an essential ingredient a soap composed of the salt of a fatty acid having at least 10 carbon atoms, said composition being normally subject to deterioration by oxidation, and stabilized by having dissolved therein a small amount of a salt of saturated N-aromatic alpha amino carboxylic acid wherein a saturated acyclic group of at least 12 carbon atoms is attached to the carbon atom alpha to the'carboxyl group, and wherein the nitrogen atom isdirectly attached to a carbon atom of the aromatic group. r

5. An organic composition comprising as an essential ingredient a soap composed of a metallic salt of an unsaturated fatty acid having at least 10 carbon atoms, said composition being normally subject to deterioration by oxidation, and stabilized by having dissolved therein a small amount of a metallic salt of saturated N-aromatic alpha amino carboxylic acid wherein a saturated acyclic group of at least 12 carbon atoms is attached to the carbon atom alpha to the carboxyl group, wherein the nitrogen atom is directly attached to a carbon atom of the aromatic group and wherein the metallic constituents of the soap and the salt are the same.

6. A calcium soap of an unsaturated fatty acid stabilized against oxidative decomposition by having dissolved therein from about 0.05% to about 5% of a soluble calcium salt of a N-aromatic alpha amino carboxylic acid wherein a saturated acyclic group of at least 12 carbon atoms is attached to the carbon atom alpha to the carboxyl group, and wherein the nitrogen atom is attached to a carbon atom of the aromatic nucleus.

7. A lithium soap of an unsaturated fatty acid stabilized by having dissolved therein from about 0.05% to about 5% of a soluble salt of a N-aromatic alpha amino carboxylic acid wherein a saturated acyclic group of at least 12 carbon atoms is attached to the carbon atom alpha to the carboxyl group, and wherein the nitrogen atom is attached to a carbon atom of the aromatic nucleus.

8. An aluminum soap of an unsaturated fatty acid stabilized against oxidative decomposition by having dissolved therein from about 0.05% to about 5% of a soluble aluminum salt of a N-aromatic alpha amino carboxylic acid wherein a saturated acyclic group of at least 12 carbon atoms is attached to the carbon atom alpha to the car- 'boxyl group, and wherein the nitrogen atom is attached to a carbon atom of the aromatic nucleus.

9. An organic composition comprising as an essential ingredient a soap composed of the salt of a fatty acid having at least 10 carbon atoms, said composition being normally subject to deterioration by oxidation, and stabilized by having dissolved therein from about 0.05% to about 0.5% of a salt of a saturated N-aromatic alpha amino carboxylic acid wherein a saturated acyclic group of at least 12 carbon atoms is attached to the carbon atom alpha to the carboxyl group, and wherein the nitrogen atom is attached to an aromatic carbon atom.

10. An organic composition comprising as an essential ingredient a soap composed of the salt of a fatty acid having at least 10 carbon atoms, said composition being normally subject to deterioration by oxidation, and stabilized by having dissolved therein from about 0.05% to about 0.5%

of a salt of a saturated N-aromatic alpha amino group, and wherein the nitrogen atom is attached carboxylic acid wherein a saturated acyclic group to an aromatic carbon atom.

of at least 12 carbon atoms is attached to thecar- ELLIS R. WHITE. bon atom alpha to the carboxyl group, and wherein the aromatic radical is-a benzene ring. 5 REFERENCES CITED 1 An ic ompos prisin as a The following references are of record in the essential ingredient a soap composed of the salt file of t i patent: of a fatty acid having at least 10 carbon atoms, said composition being normally subject to de- UNITED STATES PATENTS terioration by oxidation and stabilized by having 10 Number Name Date dissolved therein a small amount of a salt of a 2,122,408 Clarke July 5, 1938 saturated N-aromatic alpha amino carboxylic 2,154,341 Martin April 11, 1939 acid wherein a saturated non-aromatic hydro- 2,223,244 Bohm Nov. 26, 1940 carbon group of at least 12 carbon atoms is .at- 2,277,016 Guest Mar. 17, 1942 tached to the carbon atom alpha to the carboxyl 5 2,363,777 Downing et a1 Nov. 28, 1944