DE1026322B - Process for the preparation of 4,4'-bis (dialkylamino) diphenylmethanes - Google Patents

Description

It is known that 4,4 ^/ -bis (dialkylamino) diphenylmethane is obtained if an N, N-Dialkylanüin, z. B. Dimethylamine with aqueous formaldehyde solution with the addition of about 0.5 to 4 ° / ₀ acid. A wide variety of inorganic and organic acids or mixtures thereof have been proposed for this purpose, but it has not been possible to ^{carry out the reaction, which is generally carried out at about 40 to 60 °} C., in less than about 25 to 50 hours in a satisfactory yield. If according to a further proposal, as the acid catalyst is about 1 to 3 ° / ₀ sulfanilic, so the reaction proceeds somewhat more rapidly, but gives less pure end products.

It has now been found that very pure 4,4'-bis (dialkylamino) diphenylmethanes can be obtained in a considerably shorter time obtained when Ν, Ν-dialkylanilines with aqueous Formaldehyde solution with the simultaneous addition of small amounts of acid and small amounts of saturated primary or secondary amines.

The starting materials used are, for. B. N, N-dimethyl, diethyl or dibutylaniline. Instead of aqueous formaldehyde solution, it is also possible to use aqueous solutions or mixtures of compounds which split off formaldehyde, such as hexamethylenetetramine or paraformaldehyde. The acids used hitherto for this purpose, in particular hydrochloric or sulfuric acid, formic acid or sulfanilic acid, of which about 0.5 to ⁵⁰ I ₀ , calculated on the amount of N, N-dialkylaniline used, are required. Examples of amines that are added to the reaction mixture as further catalysts according to the invention are mono- and dimethylamine and -ethylamine, pyrrolidine, piperidine, mono- and dicyclohexylamine, mono- and diethanolamine, oxyethylmethylamine, ethylene and propylenediamine, diethylenetriamine. It is advantageous to use somewhat less of these amines than the amounts equivalent to the amounts of acid added.

In this procedure, if the condensations are carried out at the usual temperatures, ie. H. at about 40 to 60 ° C, an almost quantitative yield of pure Diphenylmethanderivat.das within about 4 to 6 hours if necessary, precipitates immediately in a crystalline, easily suction-able form. Sometimes recommends it is necessary to add inert diluents to the reaction mixture, which prevent crystallization during the Prevent condensation. The crystallized precipitate is filtered off with suction or centrifuged, whereupon one the filtrate, which contains the catalysts (acid and amine), can be used immediately for a new batch can.

The process can also be carried out continuously, with all or part of the aqueous layer under Supplement the low losses of acid and amine, lead in the cycle.

Method of manufacture

of 4,4'-bis (dialkylamino) -

diphenylmethanes

Applicant:

Aniline & Soda Factory in Baden
Aktiengesellschaft, Ludwigshafen / Rhein

Dr. Karl Merkel, Ludwigshafen / Rhine,
has been named as the inventor

The parts mentioned in the examples are parts by weight.

example 1

In a stirred vessel, 543 parts is filled in 1210 parts of N, N-dimethylaniline, 30% aqueous formaldehyde solution, 700 parts of water, 13 parts of ethylene diamine and 60 parts of 36 ° / _o hydrochloric acid, and the mixture is stirred for 4 to 5 hours at about 5O ⁰ C The crystal slurry which has precipitated out is then filtered off with suction and washed. 1215 parts of colorless 4,4'-bis (dimethylamino) diphenylmethane with a melting point of 88.2 ° C. are obtained.

Example 2

A very similar result as in Example 1 are obtained if the reaction in the same manner with 1210 parts Ν, Ν-dimethylaniline, 500 parts of 30 ⁰ / "aqueous formaldehyde solution, 5 parts of ethylenediamine, 23 parts of 36 ° / ₀ hydrochloric acid and 800 parts of the aqueous filtrate obtained in Example 1 performs. In the case of continuous operation, the filtrate can be circulated.

Example 3

1210 parts of Ν, Ν-dimethylaniline, 543 parts of 30 ° / ₀ strength aqueous formaldehyde solution, 500 parts of water, 17 parts of ethanolamine and 70 parts of formic acid are poured into a stirred vessel, whereupon the mixture is stirred at about 45 ° C. for 5 to 6 hours. The precipitated crystal slurry is filtered off with suction and washed. You get

70? 910/129

Claims (1)

3 4 1205 parts of colorless 4,4'-bis- (dimethylamino) -diphenyl- N, N-dialkylani] inene with formaldehyde in counter- methane with a melting point of 88.2 ° C. was water and catalytic amounts Acid, characterized in that one besides Claim: _{acid nor} ^ _a quantity of saturated primary Process for the preparation of 4,4'-bis (dialkyl- 5 or secondary amines as a catalyst with amino) -diphenylmethanes by condensing turns. ® 709 910/429 3.58