DE1051862B - Process for the preparation of N-tertiary alkyl substituted primary amines - Google Patents

Description

Ar stivC.ff, 89-0 (f

FEDERAL REPUBLIC OF GERMANY

GERMAN

kl. 12 q 1/01

INTERNAT. KL. C 07 C

PATENT OFFICE

85 IA

EXPLAINING EDITORIAL 1051862

112424 IVb / 12 q

REGISTRATION DATE: NOVEMBER 7, 1956

NOTICE
THE REGISTRATION
AND ISSUE OF THE
EDITORIAL:

MARCH 5, 1959

The invention relates to an improved hydrolytic process for the preparation of N-tertiary alkyl substituted primary amines.

The preparation of amines by hydrolysis of amides by means of acids or alkalis is known. The hydrolysis of N-tertiary alkyl-substituted amides is described by Ritter (Journal of the American Chemical Society, 1948, B. 70, p. 4048) who found that hydrolysis by alkalis gave the corresponding amines, while the Hydrolysis by acids leads to the formation of an alkene and ammonia. The alkaline hydrolysis However, it is slow.

It has now been found that when an N-tert-alkylformamide is hydrolyzed by acids the hydrolysis occurs rapidly and the product from the corresponding tertiary alkyl-substituted amine is in good condition Yield arises while the N-tert-alkylamides of homologous acids, e.g. B. the N-tert-alkylacetamides, result in an alkene on hydrolysis by means of acids.

In accordance with the present invention there is now an improved process for the preparation of tertiary alkyl substituted proposed primary amines by hydrolysis of N-tert-alkylformamides, which thereby is characterized in that the hydrolysis is carried out in the presence of acid

Strong mineral acids, e.g. B. sulfuric acid and hydrochloric acid. But it can strong organic acids can also be used, e.g. B. aryl or alkyl sulfonic acids or carboxylic acids, z. B. oxalic acid.

The amount of acid used is suitably at least one equivalent for each mole part of the N-tert-alkylformamide used, and the acid can be mixed with water in any suitable proportion be mixed, preferably with as much as is necessary to make a mixture of water and To achieve acid, which is between 10 and 85%, based on the weight of the acid.

The N-tert-alkylformamides can by reaction a tertiary olefin with hydrogen cyanide in the presence of an acidic catalyst and z. A small amount of water, as more fully described in the British patent 796 572 (German patent application dated October 30, 1956). As examples of N-tert-alkylformamides, which are used in the method according to the present invention may be mentioned: N-tert-butylformamide, N- (1,1,3,3-tetramethyl-butylformamide, N- (1-methyl-cyclohexyl) -formamide and N- (2-phenyl-isopropyl) -formamide.

The hydrolysis is carried out by heating N-tert-alkylformamide. Water and acid at a temperature process for the production

of N-tertiary alkyl substituted

primary amines

Applicant:

Imperial Chemical Industries Limited,
London

Representative: Dipl.-Ing. A. Bohr, Munich 5,
Dr.-Ing. H. Fincke, Berlin-Liditerfelde, Drakestr. 51,
and Dipl.-Ing. H. Bohr, Munich 5, patent attorneys

Claimed priority:
Great Britain 7 November 1955 and 22 October 1956

George Henry Lang, Blackley, Lancashire

(Great Britain),
has been named as the inventor

above 70 ° C, preferably between 100 and 120 ° C. Appropriately this can be done through Reflux the mixture.

hen. The length of time required will vary depending on the temperature used, but is usually sufficient a cooking time of up to 2 hours.

If desired, the N-tertiary alkylformamide can be used can be hydrolyzed directly without being affected by the medium,

in which it was created to be separated. Therefore, if z. B. the N-tert-alkylformamide by reaction a tertiary olefin with hydrogen cyanide and an acidic catalyst in the presence a small amount of water can do so

Amide hydrolyzed by adding additional amounts of water and acid and then heating will. The acidic reacting catalyst, e.g. B. sulfuric acid, so can be used simultaneously as the for the Hydrolysis required acid serve.

The tertiary alkyl-substituted primary amines can be obtained in a known manner from the hydrolysis mixture removed, e.g. B. by making the mixture alkaline with an alkali metal hydroxide or carbonate and then the amine by extraction

tion, distillation or mechanical separation.

Tertiary alkyl substituted primary amines which can be obtained by the process according to the present invention can be produced are, for. B. tert-butyl

809 768/528

amine, 1,1,3,3-tetramethyl-butylamine, 1-methyl-cyclohexylamine and 2-phenyl-isopropylamine.

According to the method according to the present invention, tertiary alkyl substituted amines can be converted more quickly and more conveniently than by aqueous alkali hydrolysis. It also increases if the amine is isolated by distillation techniques, the ratio of amine to water in the Distillate, so that the time and temperature required for heating are reduced. Maybe not basic impurities, e.g. B. hydrocarbons or unhydrolyzed amides, can easily before the Isolation of the amine can be removed from the acidic mixture and thus make subsequent cleaning treatments unnecessary.

The invention is illustrated by the following examples in which the parts and percentages are by weight relate, explained but not limited.

example 1

A mixture of 20 parts of N-tert-octylformamide and 21.4 parts of 30% sulfuric acid is refluxed for 2 hours until Boiling point heated and then alkaline by adding 100 parts of 10% sodium hydroxide solution made and distilled. A mixture of N-tert-octylamine and water is distilled into the collecting vessel. 16 parts of 85% tert-octylamine are obtained in 10 minutes, corresponding to a yield of 83 per cent of theory.

If, on the other hand, a mixture of 20 parts of N-tert-octylformamide and 37.5 parts of a 20% strength sodium hydroxide solution Is refluxed for 2 hours to the boiling point and then the tert-octylamine formed by hydrolysis from the mixture under conditions similar to those above used is distilled off, only 4 parts of 85% are obtained during a 1 hour distillation tert-octylamine, corresponding to a yield of 16.8% of theory.

Example 2

25 parts of sodium cyanide and 27 parts of water are mixed in with a stirrer and with devices mixed with a vessel provided for heating and cooling. 100 parts of 98% sulfuric acid are added gradually over the course of an hour, maintaining the temperature at 15 ° C will. When the addition is complete, 28 parts of isobutene are below the surface within 4 hours of the liquid introduced while the temperature of the reaction mixture is below 15 ° C is held. After this time, the mixture is brought to a temperature between 50 and 55 ° C heated and then stirred for a further 8 hours at this temperature. Then 100 parts of water are added; on standing the mixture separates into two layers, the upper layer being made of N-tert-butylformamide consists.

According to the invention, the mixture is then refluxed for a further hour as the starting material heated to boiling, during which time the N-tert-butylformamide hydrolyzes to tert-butylamine, which goes into solution. After this time has elapsed, 270 parts of 32% sodium hydroxide solution are produced added and the mixture is distilled into a receiver containing 200 parts of 10% aqueous hydrochloric acid contains. A mixture of tert-butylamine and water is distilled over. The distillation is in an hour completed, the aqueous solution in the template is then evaporated to dryness and gives a Amount of tert-butylamine hydrochloride that yield of 86% corresponds to the theoretical, calculated on the isobutene and sodium cyanide used.

Example 3

56 parts of commercially available diisobutene, which mainly from 2,4,4-trimethylpentene-1 and 2,4,4-trimethylpentene-2 consists of 25 parts of sodium cyanide

ίο and 27 parts of water mixed in a vessel that is provided with a stirrer and devices for heating and cooling. 100 parts 98% Sulfuric acid is then added to the mixture over the course of 2 hours, which is during the addition stirred and kept at a temperature of 15 ° C. When the addition is finished, the Mixture heated to 50 to 55 ° C and stirred for a further 8 hours at this temperature. Well be 100 parts of water are added. When standing, the mixture separates into two layers, the upper one of which consists of N-tert-octylformamide.

According to the invention, this mixture is then refluxed for 1 hour to the boiling point heated, whereby the N-tert.-OctylfoTmamid to tert.-Octylamine hydrolyzed and leaving a thin layer of unreacted diisobutene in Solution goes, which is distilled off or separated by hand. The remaining aqueous layer is then cooled, treated with 270 parts of 32% sodium hydroxide solution and distilled. One Mixture of tert-octylamine and water in a ratio of approximately 1: 1 distilled over and separates into two layers in the original. The water layer is left for about half an hour continuously returned to the still, then the distillation is complete, and the top oily layer consisting of tert-octylamine (85%) and water (15%) is obtained in an amount which, based on the sodium cyanide and diisobutene fed in, corresponds to 76% of theory.

In a similar process, which is carried out essentially as described above, but in which the reflux cooling under acidic conditions is omitted for one hour, hydrolysis takes place not held before the distillation stage under alkaline conditions, the speed of the Hydrolysis is low. The distillation takes 5 to 8 hours to complete, and so does the ratio tert-octylamine to water in the distillate is about 1: 8. The amount of tert-octylamine obtained is 73.7% of the theoretical yield, calculated on the sodium cyanide and diisobutene added, the tert-octylamine layer with unreacted diisobutene and N-tert-octylformamide is contaminated.

Example 4

A mixture of 20 parts of N-tert-octylformamide and 22 parts of 16% strength hydrochloric acid solution is used Heated for 1 hour under reflux to boiling point and then by adding 100 parts of 10% Sodium hydroxide solution made alkaline and distilled. A mixture of tert-octylamine goes into the template and water over, and 16 parts of 85% tert-octylamine are obtained in 10 minutes, which is a Yield of 83% corresponds to theory.

Example 5

If the procedure is as described in Example 3, but replaces in the preparation of the starting material

56 parts of the commercially available diisobutene by 48 parts of l-methylcyclohexene are obtained in the Submission an upper oily layer made of 1-methylcyclohexylamine (50%) and water (50%), in an amount that, calculated on the filled Sodium cyanide or l-methylcyclohexene, 73% of the theoretical yield.

Example 6

A mixture of 20 parts of N-tert-octylformamide and 75 parts of 24% oxalic acid solution is refluxed to boiling point for 2 hours and then made alkaline by adding 160 parts of a 10% sodium hydroxide solution and distilled. A mixture of tert-octylamine and water goes over into the receiver and is obtained 19.8 parts of 70% tert-octylamine in 10 minutes, which corresponds to a yield of 85% of the theoretical.

Example 7

A mixture of 16.3 parts of N- (a, a-dimethylbenzyl) formamide (Boiling point 118 ° C / 0.25 mm, melting point 40 ° C) and 76 parts of 40% sulfuric acid is heated to boiling under reflux for 2 hours, then by adding 120 parts Made 20% sodium hydroxide solution alkaline and distilled. A mixture goes out in the template 2-phenylisopropylamine and water over. The amount of 2-phenylisopropylamine obtained is 71% theory (boiling point 80 ° C / 12 mm.

Claims (5)

Patent claims: 1. Process for the preparation of N-tertiary-alkyl-substituted primary amines by hydrolysis of N-tertiary-alkyl-substituted amides, characterized in that N-tert-alkylformamides treated at temperatures above 70 C in the presence of strong acids. 2. The method according to claim 1, characterized in that the acid is a strong mineral Acid, e.g. B. sulfuric acid and hydrochloric acid is used. 3. The method according to claim 1 and 2, characterized in that the amount of acid used corresponds to at least one equivalent for each mole fraction of N-tert-alkylformamide used. 4. The method according to claim 1 to 3, characterized in that a mixture of acid and water containing between 10 and 85 weight percent acid is used. 5. The method according to claim 1 to 4, characterized in that the hydrolysis by heating of N-tert-alkylformamide, water and acid at temperatures between 100 and 120 ° C will. © 809 768/528 2. 59 '