JPH053459B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel method for producing triphenylamine or its nuclear substituted products (hereinafter abbreviated as triphenylamines). More specifically, in the presence of a hydrogen transfer catalyst, diphenylamine or its nuclear substituted product (hereinafter abbreviated as diphenylamines) and cyclohexanone or its ring substituted product (hereinafter abbreviated as cyclohexanones) are reacted, and a condensation reaction and a dehydrogenation reaction are performed. The present invention relates to a method for producing triphenylamines. Triphenylamines are compounds useful as general chemical industrial intermediates, particularly intermediates for dyes, agricultural chemicals, rubber drugs, and the like. Conventionally, triphenylamines have been produced by a method in which a potassium salt of aniline or diphenylamine is reacted with bromobenzene by heating, a method in which diphenylamine and aniline are reacted in the presence of hydrochloric acid (USP2051123), or a method in which a copper chromium oxide catalyst is reacted. It was produced by a method in which aniline and phenol were reacted (Japanese Patent Publication No. 52-48969). However, these methods have drawbacks such as complicated reaction steps and the need for large amounts of acids and bases, and the method disclosed in Japanese Patent Publication No. 52-48969 is not industrially satisfactory due to extremely low yields. It wasn't something I could do. As a result of intensive studies to improve these points, the present inventors have discovered that triphenylamines of extremely high yield and high quality can be produced by heating and reacting diphenylamines and cyclohexanones in the presence of a hydrogen transfer catalyst. We have discovered what can be done and arrived at the present invention. That is, the method of the present invention is a novel method for producing triphenylamines by a condensation reaction and a dehydrogenation reaction of diphenylamines and cyclohexanones in the presence of a hydrogen transfer catalyst. Any known diphenylamine may be used as a raw material in the method of the present invention, such as diphenylamine, 2-methyl-diphenylamine, 3-methyl-diphenylamine, 2,2'-dimethylphenylamine, etc. Examples include diphenylamine whose nucleus is substituted with an alkyl group, diphenylamine substituted with an alkoxy group, diphenylamine substituted with a halogen group, diphenylamine substituted with a carboxylic acid group, and diphenylamine substituted with a nitrile group. Further, diphenylamines having different functional groups substituted on the nucleus such as 2-methyl-4'-chloro-diphenylamine may be used. The cyclohexanones may be any known ones, such as alkylcyclohexanones such as cyclohexanone, 2-methyl-cyclohexanone, and 3,5-dimethylcyclohexanone; alkoxycyclohexanones such as 3-methoxy-cyclohexanone and 4-methoxy-cyclohexanone; Examples include hydroxycyclohexanone such as 4-hydroxycyclohexanone. The amount used is not particularly limited as long as it is equal mole or more to the diphenylamine. The catalyst used in the method of the present invention may be any catalyst used in dehydrogenation reactions, such as Raney nickel, reduced nickel, or nickel supported catalysts, Raney cobalt, reduced cobalt, or cobalt supported catalysts, Raney copper, reduced copper or copper supported catalysts, noble metal catalysts of group 8 of the periodic table or catalysts supported on carbon, alumina, barium carbonate, etc., rhenium catalysts such as rhenium-carbon, copper-
Examples include chromium oxide catalysts. Among these catalysts, palladium is preferred, and palladium catalysts supported on carriers such as palladium-carbon, palladium-alumina, and palladium-magnesium oxide are particularly preferred. The amount used is usually 0.001 to 0.2 gram atom, preferably 0.004 to 0.1 gram atom, based on the metal atom relative to the amine. In the method of the present invention, it is advantageous to use cyclohexanones as the self-solvent, and there is no need to use other reaction solvents, although there is of course no problem in using them. The temperature during the reaction can usually be carried out at 100 to 400°C, but is preferably selected in the range of 150 to 350°C. The produced triphenylamines can be obtained by treating the mixture after the completion of the reaction according to conventional methods such as distillation and crystallization. Next, the method of the present invention will be specifically explained using examples. Example 1 67.7 g (0.4 mol) of diphenylamine, 117.8 g (1.2 mol) of cyclohexanone, and 5% palladium were placed in a stainless steel autoclave with an internal volume of 500 ml.
7.33 g of carbon (manufactured by Nippon Engelhard) was charged. After replacing the inside of the autoclave with nitrogen, 260℃
The temperature rose to . After reacting at that temperature for 12 hours with stirring, the reaction mixture was cooled to room temperature and filtered to separate the catalyst. A portion of the liquid was collected and analyzed by gas chromatography to quantify unreacted raw materials and products. As a result, 11.5 g (conversion rate 82.9%) of unreacted diphenylamine remained, and 72.8 g (selectivity 89.3%) triphenylamine was produced.
After concentrating and distilling the liquid to separate and recover unreacted cyclohexanone and diphenylamine, the concentrate was
- Recrystallization from hexane gave 66.1 g of triphenylamine with a melting point of 125.8-126.6°C and a purity of 99.4% by gas chromatography. Examples 2 to 8 Reactions were carried out in the same manner as in Example 1 using various diphenylamines and cyclohexanones. The results were as follows.

[Table] Min

[Table]

8 2〓Cyano〓Diphenylamine
〃 〃 〃 90 92

Claims (1)

[Claims] 1. A method for producing triphenylamine or a nuclear substituted product thereof, which comprises heating diphenylamine or a nuclear substituted product thereof and cyclohexanone or a ring substituted product thereof in the presence of a hydrogen transfer catalyst.