DE3131096A1 - METHOD FOR PRODUCING N-SUBSTITUTED METHACRYL AND ACRYLAMIDES - Google Patents

Description

Process for the preparation of N-substituted methacrylamides and acrylamides

There are various ways of producing the technically interesting amides of acrylic and methacrylic acid Ways have been suggested.

Acrylonitrile or methacrylonitrile, for example, are among the various possible starting compounds on, among other things, because these nitriles are technically relatively easily accessible. In the simplest case you can the unsubstituted amides obtained by partial hydrolysis of the acrylonitrile or methacrylonitrile.

The so-called Ritter reaction takes a different route, in which - mechanistically speaking - carbonium ions are more sufficient Stability react with nitriles to form N-substituted amides. In practice the nitriles mostly reacted with alkenes or alcohols in the presence of sulfuric acid. The knight reaction can too can be applied to unsaturated nitriles.

(H. Plant & JJ Ritter, J.Am.Chem. Soc. 73_, 4076, (1951). In general, the following rules apply: With alcohols and olefins that form secondary carbonium ions, the Ritter reaction is much more difficult than with tertiary compounds If primary alcohols are to be converted, extremely drastic reaction conditions are required (cf. K. Hamamoto & M. Yoshioka, Nippon Kagaku Zasshi 80, Chem. Abstr. 55_, 4349 (1961).
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US Pat. No. 2,448,991 discloses a process for the preparation of N-isopropyl methacrylamide by mixing Isopropyl alcohol with methacrylonitrile at elevated temperature in the presence of an acidic catalyst.

According to FR-PS 1 436 391 1: T mixtures of Acrylonitrile and isopropanol reacted together with 3 moles of sulfuric acid in a reactor. After neutralizing with ammonia, for example, by extraction with

Worked up xylene.

US Pat. No. 3,161,679 also teaches the reaction of unsaturated nitriles and olefins having 10 to 40 carbon atoms, an excess of 30 to 250 % of sulfuric acid being added to the mixture of nitrile and olefin. Working up is done by pouring it onto ice and then neutralizing it.

Acrylic and methacrylamides with oct-methyl substituted Alkyl radical with 5 to 10 carbon atoms or a more-

poly-branched alkyl radicals with about 6 to 8 carbon atoms on nitrogen can be produced according to European laid-open specification 0 004 362 with the aid of the Ritter reaction.
'N-3-Aminoacrylamides are according to Can. PS 996 128 made accessible by applying the Ritter reaction to the corresponding aminoalkylenes.

The proposed procedures could not be fully satisfactory. Further work therefore turns the synthesis of N-substituted amides of the <x, ß-unsaturated Carboxylic acids from the unsaturated nitriles using other specific catalysts.

So in Japan. OS 75/135018 Silicon, phosphoric or tungsten molybdic acid recommended as catalysts for the production of N-substituted acrylamides. From US-PS 3,948,989 the use of PdCI ₂ as

20 known catalyst for the production of N-tert-butyl acrylamides from acrylonitrile and tert-butanol or isobutylene. \

However, the proposed embodiments of the Ritter reaction were not entirely satisfactory.

There was still the task of making a method available to ask, in which in the simplest possible manner and with good yields. the acrylonitrile or the Methacrylonitrile and as wide a variety of

starting compounds capable of forming carbonium ions are the N-substituted acrylic or methacrylamides can be produced.

It has been found that N-alkylamides of the formula I ⁰ Al

Hp - η C XT T

¹ V ^H

wherein R ^ is hydrogen or methyl and R- is an alkyl radical having at least 2 to 40 carbon atoms, in one of the requirements of
Technique can be produced in a satisfactory manner if you use a nitrile of the formula II

H ₂ Ci = CC === s N II

H

wherein R _{1 is} hydrogen or methyl with an alkyl compound capable of forming carbonium ions (Rp *) with at least three carbon atoms (compounds of the formula ILI) under the action of sulfuric acid in such a way that the nitrile is reacted
Formula II together M adds a slight deficiency to a slight excess of the compound capable of forming cations to an equimolar amount of sulfuric acid up to a mol excess of sulfuric acid,

allowed to react at 10 to 100 ^° C. and after dilution, preferably without neutralization of the sulfuric acid, worked up by separating the N-alkylamides of the formula I which separate out and / or by extraction with an inert extractant which is essentially immiscible with the dilute sulfuric acid.

In general, the nitrile of the formula II with the compound capable of forming cations is im Ratio 1: 0.9 to 1: 1.1 mol implemented. It has been found useful to adjust the water concentration As little as possible in the reaction mixture up to work-up, e.g. in the catalytic range, based on the Nitrile of the formula II or the alkyl compound of the formula III to keep.

Under the conditions mentioned above, under the action of sulfuric acid (i.e. the conditions of the Ritter reaction) capable of forming carbonium ions. Alkyl connections should, according to the invention, the Optionally substituted alkyl compounds accessible to the Ritter reaction, primarily the Formula IIIA

• κ.

wherein Rj, R * and RX or an optionally substituted one Alkyl radical with 1 to 21 carbon atoms or

■ St

hydrogen

is an aryl radical and R _{fi is} an optionally substituted alkyl radical with 1 to 21 carbon atoms or * two of the radicals R_, R., Rr and Rg together form a ring and with the proviso that at most two 5 of the radicals R ,, R ₁ , Rr and R, - should stand for an aryl radical, as well as

the alcohols of the formula IIIB

/ ^R 5

R ₇ C OH

wherein R- is an aryl radical or a radical

y, CH stands,

»I f

where R ,, R. and Rr have the same meanings as R ,, R. and Rr, and R, - is hydrogen, an optionally substituted alkyl radical having 1 to carbon atoms or an aryl radical or 2-> two of the radicals R ,, R., R ₅ and R ₆ together form an aliphatic ring and with the proviso that

I I

at most two of the radicals R- to R _ß and R ₇ should stand for an aryl radical, to be understood.

. an optionally substituted aryl radical or

H.

"Optionally substituted" alkyl radicals are to be understood as meaning alkyl radicals with substituents that survive the conditions of the Ritter reaction without disadvantageous secondary reactions, for example phenyl radicals, acid amide radicals, alkyl or aryl ketone radicals, etc. An aryl radical in the context of the present invention is a Understood phenyl or a naphthyl radical, which in turn can be substituted with inert substituents.
10

In carrying out the reaction with the starting compounds of formula III, the olefins of the formula IIIA or the alcohols of formula IIIB is generally sufficient, a reaction temperature 40-40 ⁰ C when tertiary carbonium ions are formed from the starting compounds under the reaction conditions prevailing opinion. 100 ⁰ C attached - when the reaction proceeds under formation of secondary carbonium ions, for example, 60 are generally higher temperatures. The reaction is generally carried out without the application of pressure.

In general, the reaction can with acrylonitrile CFormel I, R, = hydrogen) at around 10-30 ⁰ C lower reaction temperature than the door can be carried out with methacrylonitrile (Formula I, R ₁ = methyl).

Particularly noteworthy is the reaction with the olefins or alcohols of the formula III with a low carbon number, for example the reaction with olefins with ^ Q 3 to 5 carbon atoms. The reaction with propylene, isobutylene, pentene-1, η-butene and others may be mentioned

Also of interest is the reaction with alcohols having 3 to 5 carbon atoms, for example the reaction with tert-butanol, tert-amyl alcohol, propanol-2, butanol-2, and others
5

Also of interest is the reaction with terminally unsaturated olefins, such as from pentene-1 to Heneicosen-1, for example hexene-1, octene-1, Decene-1, tetradecene-1, octadecene-1, the implementation with cyclic compounds such as cyclopentene, cyclohexene, norbornene, etc.

Furthermore, the reaction according to the invention removes the corresponding amides of the formula I in a simple manner more complex cyclic alcohols or olefins accessible, e.g. from isoprene derivatives such as the bicycles, Borneol, norbornene or from tr! Cyclic systems such as adamantol, as well as the reaction with substituted compounds of formula III, such as phenyl-substituted

20 compounds such as styrene, α-methylstyrene, benzyl alcohol, etc.

The use of higher α-olefin mixtures, e.g. the so-called SHOP olefins, should also be mentioned.

The implementations are of particular technical interest with isopropanol or with tsrt.-butanol to N-isopropylmeth-

respectively

acrylamidVzu fo-tert-butyl methacrylamide and the corresponding n-acrylamides.

·

-y-

The method according to the invention is notable. among other things by the fact that on the, especially under technical Conditions laborious step of neutralization of the sulfuric acid can be dispensed with. In particular In the case of products of the formula I with higher alkyl substituents (carbon number ^. 4), the product separates often as a second phase, crystalline or as an oil. After separating off the second phase formed can with a suitable, essentially incompatible with the aqueous j

Sulfuric acid miscible, inert extractant ex-;

to be watered. Examples of suitable extractants are optionally halogenated hydrocarbons, such as toluene, methylene chloride or ethers, such as Diethyl ether et al.

The conduct of the reaction has proven to be particularly advantageous. proven, in which the two components of formulas II and III are added together to the sulfuric acid in the template, the sulfuric acid being expedient

20 is already at about the implementation temperature.

The concentrated sulfuric acid used according to the invention is generally 95-100%, preferably 96-98% acid.
The reaction time in the process according to the invention is generally 0.5-4 hours. That makes a difference

the procedure is advantageous from certain procedures of the «

State of the art that requires significantly longer response times |

take advantage of. The addition mode (addition of the Components of formulas II and III in a mixture for the reaction

^ O temperature located sulfuric acid) with regard to the technical Implementation (continuous or discontinuous process, process control) proved to be extremely advantageous; while the prior art methods left something to be desired in this regard.

3131036

- Υ'- 4t

In general, the work-up is carried out by diluting the reaction mixture with, as a rule, 10 40 mol of water per mol of nitrile of the formula II used, corresponding to a dilution of the sulfuric acid to a content of about 20-50 % . Another advantage of the process according to the invention is that the crude product can generally be isolated without neutralization by means of filtration, phase separation and / or extraction. The sulfuric acid obtained can advantageously be regenerated, for example by the methods customary in technology.

To increase the product yield and / or the product purity, a neutralization

step contribute. In such cases, the neutralization step is advantageously after isolation of the crude product ■ (unsaturated N-alkylamide of the formula T) _f performed. The neutralization is preferably carried out with ammonia in the gaseous or aqueous state.

The method according to the present invention is suitable - in contrast to the comparable procedures of the State of the art - to be carried out on an industrial scale. It is of particular interest that the

Process according to the invention is suitable for continuous implementation. Given the relatively high concentrations the reactants and the reaction media and the short residence times can also be used in the technical Implementation relatively, small equipment application

30 find. Because of the mild conditions of the reaction (no pressure, maximum 100 ⁰ C), reaction vessels made of easily accessible materials can be used, such as glass, enamel clothing, V4-A steel, etc.

Examples 1-12

96% sulfuric acid is initially introduced and brought to the reaction temperature. While stirring and cooling is now a mixture of methacrylonitrile and olefin or alcohol was added dropwise at reaction temperature within 45-90 min and then stirred at the reaction temperature. The methacrylonitrile was previously treated with 50 ppm hydroquinone monomethyl ether and 15 ppm 4-methyl-2,6-di-tert-butyl phenol stabilized.

The reaction mixture is poured into ice water (min 10-15 moles of H-O per mole of nitrile used), Stirred for 30 minutes and the crude product obtained by filtration, phase separation or extraction. Further purification

can, if necessary, be carried out by fractional vacuum distillation or unicrystallization.

example Amounts used [mol] Olefin or alcohol «2» « Reaction conditions t [h] yield ι product No. Methacrylonitrile Cyclohexene 2.5 5 T ['C] 4th [% of theory 1 2.5 Isopropanol 2.6 5 45 4th 97 N-Cyclohexyl-methacryl
amide 2 2.5 tert. Butanol 1.5 2.5 80 3 76 N-isopropyl-methacrylic
amide 3 1.25 tert. Butanol 1.5 2.5 15th 3 86 N-tert. Butyl methacryl
amide 1.25 Isobutylene 2.6 3.75 40 3 55 N-tert. Butyl methacryl
amide 5
<4 I.
'i 2.5 Acetone »2.4 2.4 10 4th 92 N-tert. Butyl methacryl
amide ', 6
t> I f 1 Mesityl oxide 1.2 2.4 60 4th 80 N- [1,1-dimethylbutene-3-
on] methacrylamide ι, '. ₍ 7
oj ,, ' 1 Norbornene-2 0.5 1 60 3 76 7 '; 8th 0.5 Adamantanol-1-0.33 1.3 65 3.5 82 N-norbornyl methacrylic
amide 9 0.33 d 1-borneol - '· ■ 0.5 1 50-70 4th 96 N-adamantyl methacrylic
amide 10 0.5 Decene-1 1, · ' 2 70 3.5 * 87 N-borneyl methacrylic
amide 11 1 Decanol-2 0.16 0.32 50 3 38 N-decyl methacrylamide 12th 0.16 65 96 N-decyl methacrylamide in 350 ml glacial acetic acid CO a.) solved in 150 ml acetic acid i b_.) solved t -> CD
CO

r 13 / W ?.

Example 13 approach:

Apparatus:

Execution:

250 mol (25.6 kg) 96 Ug H ₂ SO ₄

150 mol (11.2 kg) tert-butanol

125 moles (8.4 kg) methacrylonitrile

1 g of di-tert-butyl-p-cresol

120 1 vessel, stirrer, cooler, sight glass, Inlet, cooling brine

_{25.6 kg of 96 Ug H 2} SO ₄ were placed in a 120 1 kettle and heated to 10 ^° C. with cooling brine. A mixture of 1 g of di-tert. butyl-p-cresol, 8.4 kg methacrylonitrile and 11.2 kg of tert-butanol was heated under stirring and cooling (cooling brine) at a reaction temperature of 10 within 2 1/2 - added dropwise over 18 ^e G. Then 3 1/2 h were at 16 - 21 ⁰ C stirred. At 9-22 ° C, 35 1 were distilled. H ₂ O was added, a white crystalline precipitate formed. The reaction mixture was brought to pH 7-8 with 29.7 kg of 25% strength ammonia solution while cooling, and the temperature rose to a maximum of 26 ° C. The reaction mixture was stirred at room temperature overnight. The next morning, 20 1 of distilled water were added to the reaction mixture. H ₂ O given, the product sucked off through a suction filter and 10 1 dist. Rewashed H ₂ O. The white crystals which had been suctioned off were ^{dried overnight at 30 °} C. in a drying cabinet.

The total yield is 15.36 kg, that is 87.0 % of theory. Purity according to GCa> 98.5 %. Mole weight 141 “2 Melting point: 6O ⁰ C

Example 14

Batch size: 250 mol (25.6 kg) 96% H ₂ SO ₄

125 moles (8.4 kg) methacrylonitrile 5 150 moles (9.02 kg) isopropanol

1 g of di-tert-butyl-p-cresol

Apparatus: 120 1 boiler, stirring, cooling, steam heating (Low pressure steam) 10

Execution:

In a 120 1 tank 25.6 kg 96 Iige H ₂ SO ₄ were initially charged and heated with low pressure steam at 90 ^e C. A mixture of 1g di-tert. butyl-p-cresol, 8.4 g of methacrylonitrile and 9.02 kg of isopropanol was added over 45 min with stirring and cooling (water) at a reaction temperature of 90 - 103 ⁰ C are added dropwise. Followed by 2 1/4 was stirred at 91 - 106 ⁰ C stirred. At 30-50 ^° C., 34 l of dist. H ₃ O added. With 25 Uger

Ammonia solution, the reaction mixture was brought to pH while cooling, and the temperature rose to a maximum of 56.degree. The reaction mixture was stirred at room temperature overnight; the product crystallized out. The next morning, the reaction mixture was filtered off with suction through a suction filter and washed with about 35 l of ice water. The extracted light yellow crystals were over the weekend at 30 ⁰ C in a drying oven dried (8.5 kg Roliprodukt). The mother liquor and the filtrate were stirred with 10 l of methylene chloride. The organic phase was separated off, _{dried with Na 2} SO ₄ , filtered and rotated

concentrated steamer (3.2 kg of crude product). The total raw yield is 11.7 kg, which is 73.5 % of the theory.

Example 15

1 mole% sulfuric acid was placed, heated to 40 ⁰ C and with stirring and cooling within 35 min with a mixture of 0.5 mol of acrylonitrile, 70 g of Cg - C ₁₂ olefin (SHELL) and 5 mg of di-tert. butyl-p-cresol added. (The reaction temperature rose to a maximum of 45 ° C.).

The mixture was subsequently stirred at 40 ° C. for a further 3 h ^ O the reaction mixture poured into 400 ml of ice water.

After 15 minutes, the aqueous mixture was extracted twice with methylene chloride, and the organic phases were combined and the methylene chloride removed. The desired product mixture was obtained in a crude yield of 99 liters.

Example 16

Analogously to Example 15, but at 20-24 ^e C reaction temperature, the yield is 96% of theory

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Example 17-25

Preparation of N-decyl-acrylamide

An equimolar mixture of decene-1 and acrylonitrile is ^ 5 at reaction temperature to the sulfuric acid presented (96 Iig) added dropwise, stirred; the reaction mixture in Given ice water and the product obtained by extraction and removal of the extractant.

example H ₂ SO ₄ T t HO crowd yield No. [Mole / mole nitrile] [• c] [H] [Mole / mole nitrile] [% of theory] 17th 2 30th 1 20th 72 18th 2 30th 4th 20th 87 19th 2 30th 3.5 4th 60 20th 2 30th 3.5 8th 67 21st 2 30th 3.5 16 85 22nd 2 30th 3.5 40 83 23 1.4 ■ I
30th 4th 20th 70 24 3 30th 4th 20th 94 ι
25th 2 60 ^; 0.5 20th 86

Claims (9)

Process for the production of N-substituted methacrylamides and acrylamides Claims (s I.) Process for the production of unsaturated N-alkylamides of the formula I. 1 ^H. where R _{1 is} hydrogen or methyl and Ί5 R _{2 is} an optionally substituted, optionally cyclic alkyl radical having at least 3 and up to 40 carbon atoms, characterized in that 20 dass.man a nitrile of the formula II H ₇ C == C—— CN II ^R 1 in which R _{1 is} hydrogen or methyl with an optionally substi-30 capable of forming a carbonium ion (R ^) under the action of sulfuric acid . all in all 313109S tuted, optionally cyclic alkyl compound with at least 3 and up to 40 carbon atoms (alkyl compound of the formula III) is reacted with sulfuric acid in such a way that the nitrile of the formula II together with the alkyl compound of the formula III to form an equimolar to twice the molar amount of concentrated sulfuric acid, which is at the intended reaction temperature is added, then allowed to react ^{further at a reaction temperature of 10 to 100 0} C and, after dilution with water, the unsaturated N-alkylamides of the formula I, optionally by extraction with an inert extractant which is immiscible with the dilute sulfuric acid isolated. 2. The method according to claim 1, characterized in that that one was able to form carbonium ions (R-) under the action of sulfuric acid Compound of the formula III the olefins of the formula IHA 20 RP ^ ' HIA *
wherein R ,, R ^ and R ^ V or an optionally substituted alkyl radical having 1 to 21 carbon atoms or an aryl radical and R _{6 is} an optionally substituted alkyl radical having 1 to 21 carbon atoms or two each of the radicals R ₃ , R ^, Rr and R ₆ together form a ring and with the proviso that at most two of the radicals R ₃ , R ₄ , R ₅ and R _{6 should represent} an aryl radical. hydrogen **
an optionally substituted aryl radical or 3. The method according to claim 1, characterized in, that one was able to form carbonium ions CRo) under the action of sulfuric acid Compound of the formula III the alcohols of the formula IHB GE UIB R ₇ -C- wherein R- is an aryl radical or a radical > ■ CH stands, f I I where R--, R ^ and R ^ have the same meanings as R ,, Rm and Rr, and R _{6 represents} hydrogen, an optionally substituted alkyl radical having 1 to 21 Carbon atoms or an aryl radical or each on lift ^2υ two of the radicals R ₃ , R *, R ₅ and R _fi together form an aliphatic ring and with the proviso that at most two of the radicals R ₃ to R ^ and R ₇ should stand for an aryl radical. 4. The method according to claims 1 to 3, characterized in, that the nitrile of formula II and the alkyl compound of formula III are in a molar ratio of 1: 0.9 to 1: 1.1. 5. The method according to claims 1 to 4, characterized in that that the reaction time is 5 minutes to 4.5 hours. 6. The method according to claim 2, characterized in that in the formula IIIA R., R ₅ and R, have the meaning hydrogen and R_ is C ₁ -C ₁₂ . 7. The method according to claim 1, characterized in that the alkyl compound of the formula III Isopropanol, tert. Butanol, cyclohexanol, benzyl alcohol or isobutylene or cyclohexene can be used. 8. The method according to claim 1, characterized in "characterized that it is carried out continuously. 9. The method according to claims 1 to 8, characterized in that the water concentration in the Reaction batch is kept in the catalytic range until work-up.