DED0013763MA - - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

Registration date: December 4, 1952. Advertised on September 29, 1955

GERMAN PATENT OFFICE

The invention relates to an improved process for the preparation of acrylic acid amide and α-substituted acrylic acid amides.

In the French patent specification 882 123, the elimination of hydrogen halide from halogenated Carboxylic acids described with the formation of amides. After this extremely cumbersome procedure it gets using alkali metal hydroxides substituted amides.

It is known from US Pat. Nos. 2,471,927 and 2,471,994 that methacrylic acid nitrile is good Produce yields. It is also known to use acrylic acid amides using ethylene and to produce acetone cyanohydrin as starting materials, i.e. using the extremely toxic Cyanoic acid. Also that used as starting material in the known Reppe processes Acetylene has disadvantages insofar as high pressures are required for its further processing.

There has now been a new process for the preparation of acrylic acid amides and α-substituted acrylic acid amides found that opposite the

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the prior art has significant advantages and the starting material ions of which are compounds which are easy to prepare or obtain.

KiTmdgemäl.i is a propionic acid amide general l'Ormel

, N

CII .. CHR., - CONH.,

heated, in which R and R, hydrogen or an alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, aryl or substituted aryl radical or both together with the nitrogen atom form a heterocyclic king and R _{2 is} a hydrogen atom or an Al! ; yl or substituted alkyl radical, whereby an acrylic acid amide of the general Ι'ΌπηοΙ

CH., CR., CONH.,

and an aniin of the formula

R Nil R ₁ ,

in which R, R ₁ and R _{2 have} the same meaning as indicated above, are formed.

The radicals R. and R ₁ can be hydrogen or alkyl, such as methyl, ethyl, n-1'ropyl, η-butyl, isopropyl, isobutyl; Cycloalkyl such as cyclopentyl, cyclohexyl; Aryl, such as phenyl, toly, xylyl, benzyl; oiler alkyl,

Cycloalkyl or aryl with oxy and alkoxy groups, e.g. B. methoxy, ethoxy groups or halogens, e.g. B. chlorine or bromine, or nitro groups or Carboxyamidoalkylgruppon, z. B. // - Carboxyamidoätliyl- and Carboxyainidopropylgruppen, as substituents. The radical R ₂ can be hydrogen or alkyl, such as methyl, ethyl, propyl, isopropyl, η-butyl, isobutyl, which can also be substituted by an oxy, alkoxy, nitro group or by halogen.

Compounds which have been found to be particularly suitable are those in which the radical R _{2 is} a hydrogen atom, the radicals R ₁ and R are hydrogen, alkyl or / i-carboxyamidoethyl groups.

The heat treatment of the propionuramides used as starting material can be carried out at ordinary, elevated or reduced pressure and in the presence or absence of cracking catalysts, such as strong mineral acids, but preferably in the absence of such catalysts. The temperature at which the heat treatment is carried out can vary within wide limits. It depends among others on the applied pressure in the heat treatment and is between 100 and 300 ^0, preferably between 150 and 250 °.

This heat treatment is expediently carried out in a distillation device, so that one or several of the reaction products formed are distilled off during the reaction or afterwards be able. So z. B. the heat treatment under j

fio such conditions take place that the amine alone us the reaction mixture distilled off and a mixture from the acrylic acid amide formed and the unreacted propionic acid amide in the reaction vessel remains behind. The acrylic acid amide can be obtained from the residue, for example by Crystallization in the presence of a suitable solvent, are deposited. The implementation can can also be carried out under conditions that both the amine and the acrylic acid amide are selected Distill off the reaction mixture and place unreacted propionic acid amide in the reaction vessel remains. It may be advantageous to use a distillation column to prevent that Propionic acid amide distilled over. The acrylic acid amide and the amine are expediently mutually exclusive separate collection vessels fractionally condensed to reunite the two reaction products to prevent.

The heat treatment is preferably carried out in the presence of polymerization inhibitors, and although expediently made by those which are volatile at the reaction temperature. If the Heat treatment is carried out in a distillation device, it is useful to have two such To use preventive agents, one of which is relatively non-volatile and in the reaction mixture should remain, while the volatile other distilled over with the acrylic acid amide and prevents its polymerization in the distillation column. Relatively non-volatile preventive agents are for example hydroquinone, pyrogallol, N-phenyl-H-naphthylamine, copper, sulfur, volatile preventive agents on the other hand thymol, tertiary butyl catechol, triethylamine, quinoline, Isooctylmorpholine, N, N-di-isooctylmethylamine. The volatile preventive agents become useful chosen so that their boiling point is close to that of the acrylic acid amide formed.

The preferably used as a starting material / ^r i-aminopropionamide, di - (/? - carboxyamidoethyl) amine or tri - (/? - carboxyamidoethyl) amine is obtained by treating an acrylic acid ester, e.g. B, of methyl acrylate or methyl acrylate with ammonia. Other substituted / I-aminopropionic acid amides are obtained by reacting acrylic acid esters with suitable amines and then reacting with ammonia. The reaction with ammonia or amines is expediently carried out at room temperature.

The triamides N (CH, - CHR - CONH ") _a and the diamides N (CH ₂ -CHR-CONHo) ₂ decompose during the heat treatment, probably in stages, preferably with the formation of the corresponding diamides or monamides and the acrylic acid amide. Acrylic acid and ammonia are then formed almost simultaneously from these products.

The following examples serve to illustrate the process according to the invention. The specified parts by weight or parts of space correspond to g and ecm. The percentages given relate if nothing else is noted, based on weight percent.

example 1

A mixture of 34.4 parts by weight of double-distilled methyl acrylate and 44 parts by weight Diethylamine was left at room temperature for 24 hours.

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temperature left to stand. Thereafter, the mixture was first distilled at ordinary pressure for recovering the excess Diäthylamins and then under reduced pressure to remove the / S-Diäthylaminopropionsäuremethylesters (bp 75-76 ⁰ at a pressure of 14 mm mercury).

60.5. Parts by weight / methyl 3-diethylaminopropionate was added to 46 parts by volume of concentrated ammonia aqueous solution, and the mixture was allowed to stand at room temperature for 5 days. Then most of the water and the excess ammonia were evaporated off under reduced pressure, whereby 63 parts by weight of crude, still hydrous / 3-diethylamine propionic acid amide were obtained. 33.8 parts by weight of this crude / 9-diethylaminopropionic acid amide were distilled from a Claisen flask at 18 to 22 mm of mercury. There were obtained two fractions acrylamide, namely 137-155 ⁰ mm mercury at 22 18.8 parts of the 43.4 ° / ₀ containing acrylamide, and between 155 ° at 22 mm Hg and 152 ⁰ mm Hg at 18 3.8 Parts containing 26.1% acrylic acid amide.

Example 2

10 parts by weight / S-diethylaminopropionamide, which had been prepared according to Example 1, were 30 minutes with 0.5 parts by weight of hydroquinone am Reflux condenser at a temperature of 170 ° and under a pressure of 15 mm of mercury to the boil heated. 2.8 parts by weight of acrylic acid amide and 2.9 parts by weight of S-diethylaminopiopionic acid amide were formed remained unchanged.

Example 3

10 parts by weight of / 3-Diäthylaminopropionsäureamids prepared according to Example 1 and 0.5 parts by weight of hydroquinone were heated for 1 hour under reflux at 15 mm Hg pressure at a bath temperature of 170 ⁰ to boiling. 3.4 parts by weight of acrylic acid amide were formed, and 2.3 parts by weight of β-diethylaminopropionic acid amide remained unchanged.

Example 4

The procedure described in Example 3 was repeated ten times, except that there used / 3-diethylaminopropionamide each time by 10 parts by weight of the following compounds was replaced: / 3-dimethylaminopropionamide, ß-di-n-butylaminopropionamide, / S-methylethylaminopropionamide, / J-di- (y-oxypropyl) aminopropionic acid amide, / 5-N-piperidylpropionic acid amide, / J-dicyclohexylaminopropionic acid amide, / S-N-Me-

ethyl N- (4-methylcyclohexyl) aminopropionic acid amide and / J-N-methyl-N- (4-oxycyclohexyl) aminopropionic acid amide. The amides were refluxed for 1 hour. In any case it was obtained as in Example 1 acrylic acid amide.

Example 5

A mixture of 50 parts by weight ß-Diäthylaminopropionsäureamid, which had been prepared according to Example 1, and 2 parts by weight of hydroquinone was distilled in a nitrogen atmosphere over a column packed with wire mesh rings of stainless steel column, the temperature of the surrounding the reboiler bath was 165 to 190 ^0th The resulting product was collected at a vapor temperature of 100 to 12 ° ^C at a pressure of 14 mm of mercury, namely 22.8 parts by weight of a white crystallized distillate containing 63% monomeric acrylic acid amide and some acrylic acid amide polymer.

Example 6

28 parts by weight / 3-diethylaminopropionamide prepared as in Example 1 was distilled in a manner similar to Example 5 by adding the / S-diethylaminopropionamide dropwise to the distillation vessel. In addition, 0.5 parts by weight of hydroquinone were added to the distillation vessel and a further 0.5 parts by volume of quinoline were added dropwise to the β-diethylaminopropionamide. The bath temperature of the distillation vessel was kept at 190 ⁰ , while the pressure in the distillation vessel was 18 mm of mercury. The / S-diethylaminopropionic acid amide was added to the still in such a manner that a uniform distillation was maintained. 11.8 parts by weight of white crystalline distillate were obtained which contained 86% monomeric acrylic acid amide and only a trace of acrylic acid amide polymer.

Example 7

The procedure of Example 6 was repeated exactly except that the 0.5 part by weight Hydroquinone were successively replaced with 0.5 parts by weight of the following compounds: pyrogallol, N-phenyl-a-naphthylamine and copper. It Practically the same results as in Example 5 were obtained.

Example 8

The procedure of Example 6 was repeated exactly except that the 0.5 volume part of quinoline were successively replaced by 0.5 parts by volume of the following compounds: thymol, tert-butyl catechol, Triethylamine, isooctylmorpholine and N, N-di-isooctylmethylamine. 'It got practical the same results as in Example 5 were obtained.

Example 9

86 parts by weight of methyl acrylate became more concentrated aqueous together with 200 parts by volume Ammonia solution left to stand for 8 days at room temperature. From the deep brown colored The solution was the water and the excess ammonia under a pressure of 20 mm of mercury evaporated, making 75.1 parts by weight blacken, tarry mass were obtained from the crude tri- (/ 5-carboxyamidoethyl) amine,

N (CH ₂ -CH ₂ -CONH ₂ ) ₃ ,

was obtained by washing with ethyl alcohol. 19.8 parts by weight of this triamide were made from one

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Claims (4)

D 13763 IVc / 12 ο Claisen flask attached to a 12 χ 2 cm "Vigreux .." column (12 cm long, 2 cm diameter), with a beard temperature of 20S to 230 "distilled under a pressure of 15 mm of mercury. 11.2 parts by weight were crystalline Obtained distillate, which consisted of 85% acrylic acid amide. The procedure of this example was repeated exactly, the .Si) parts by weight of methyl acrylate were replaced by 100 parts by weight of methyl methacrylate / .l. The triamide formed, tri- (2-carboxyamido-i-propyl) -ainine, N (C IL - ■ - CH (ClL ₁ ) - CON H ₂ ), yielded metliykicrylsäureamid and during distillation Ammonia. Example 10 The di - (/? - carbomethoxyethyl) amine is obtained from methyl aerylate and concentrated aqueous ammonia solution at room temperature and subsequent distillation at 92 to roo ° and a pressure of 0.2 mm Hg. After standing for four days at room temperature, this amine gives the corresponding l) i - (/ i ~ earboxyamidoethyl) amine with excess concentrated aqueous ammonia solution. 21 parts by weight of this diamide were distilled at a bath temperature of 200 to 230 ⁰ under a pressure of rj mm of mercury and yielded 7 parts by weight of crude acrylic acid amide, which boiled at 110 to iiS ° below 13 mm Hg. The procedure of this example was repeated exactly, replacing methyl acrylate with methyl methacrylate was replaced. The formed di- (2-carl) oxyainido-i -]) ropyl) -amine, N 1-1 (C IL - - CH (C. 11.,) - CONH ₂ ). ,,
yielded methacrylic acid camide and in the distillation Ammonia. Example 11 From methyl acrylate and n-butylamine, one receives after standing for one day at room temperature / i-n-Butylaminopropionic acid methyl ester C ₁ H ₁ , NH CH ₂ CH ₂ -COOCH ₃ from the boiling point () i ° at 14 mm Hg. This gives at treatment with concentrated aqueous ammonia after standing for six days at room temperature / i-n-Butylinopropionic acid amide. The water and the excess ammonia was evaporated from the mixture under reduced pressure. After Drying, the crude product had a melting point of 72 to 7 (1 ". 52 parts by weight of this crude amide were as in the example (> at a bath temperature of 200 ° and a pressure of 15 mm of mercury distilled. 22 parts by weight of acrylic acid camide were formed as a white crystalline distillate. Example 12 If example 11 is repeated exactly, replacing the n-butylamine with the following amines: Ethylamine, ethanolamine, cyclohexylamine, 4-oxycyclohexylamine, benzylamine and p-oxybcnzylamine, the corresponding aminopropionic acid chambers were formed. When this propionic acid camicle described in the Were distilled manner, the acrylic acid amide was obtained in the same yield. Pa τ κ ntan s ρ r ü c. η k: i. Process for the production of acrylic acid amide and -substituted acrylic acid amides of the general formula CH ₂ = CR ₂ - CONH ₂ , characterized in that a propionic acid amide of the general formula / N - CH ₂ - CH - CONH ₂ , in which R and R _{1 are} hydrogen or an alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, aryl, substituted aryl radical or both together with the nitrogen atom form a heterocyclic ring and R _{2 is} a hydrogen atom or an alkyl or substituted one is alkyl, to a temperature zwisehen 100 and 300 ^0, suitably between 150 and 250 °, with elimination of an amine of formula R-NH-R ₁ is heated. 2. The method according to claim 1, characterized in that that the propionic acid amide used is heated in a distillation device and at least one of the reaction products formed is distilled off from the reaction mixture. 3. The method according to claim 1 and 2, characterized in that the heating is carried out in the presence of a polymerisation inhibitor, expediently a volatile and a non-volatile inhibitor. 4. The method according to claim 1 to 3, characterized in that the propionic acid amide 105. / i-n-butylaminopropionic acid cainide, di - (/? - carboxyamidoethyl) amine, Tri - (/? - carboxyamidoä, thyl) amine or / 9-diethyl aminopropionamide used. Referred publications: French Patent No. 882 123;
U.S. Patent Nos. 2,471,927, 2,471,994. O 509 562/30 9. 55