A kind of improved method of preparing 4-biphenylnitrile

Abstract

The present invention relates to a method for preparing 4-biphenylnitrile, comprising: (1) in the presence of a Lewis acid catalyst, reacting N-methylcarbamoyl chloride and biphenyl through Friedel-Craft to prepare N-methyl- The step of 4-biphenylcarboxamide; and (2) the step of obtaining the target object by removing methanol from N-methyl-4-biphenylcarboxamide in the presence of a catalyst. The present invention replaces trichloroacetyl chloride in the prior art with N-methylcarbamoyl chloride, and reacts with biphenyl. In this way, the step of separating and purifying the reaction medium after each batch of chloroform reaction in the prior art is avoided, and the operating cost is reduced. In addition, the raw materials used in the present invention are also cheap and easy to obtain, and the reaction process is easy to control, and the yield of the product after recrystallization can reach 70% or more, which can be directly used in the production of C.I. Pigment Red 264.

Description

technical field [0001] The present invention relates to a method for preparing 4-biphenylnitrile. Background technique [0002] 4-Biphenylnitrile is a key intermediate in the production of pigments (C.I. Pigment 264). About the synthesis of 4-biphenylnitrile, a variety of methods have been reported in the literature, which are briefly described as follows: [0003] 1) Biphenyl diazonium salt-cyanide method : Biphenyl is subjected to mixed acid nitration, reduction (to obtain 4-aminobiphenyl), diazotization (generated diazonium salt) and reaction with sodium cyanide to obtain 4-biphenyl nitrile (Mettler HP, patent No.: DE19833409 ( 1998-12-24)). In this method, two intermediate products (4-nitrobiphenyl and 4-aminobiphenyl) are generated, both of which are carcinogens, and the sodium cyanide used is a highly toxic substance, so during the production process, the operator's Poor physical and mental health. [0004] 2) Biphenyl bromination-cyanation method : Biphenyl is ...

AI Technical Summary

Problems solved by technology

The defect that this method exists is: the price of harsh reaction condition and used catalyst is expensive, so that this method does not have commercial value at present

The disadvantage of this method is: the preparation steps are tedious, although the yield of each step reaction is not low, the total yield is not high, so that the method has lost its economic value

But this method also has a shortcoming, that is, although the result of chloroform reaction has generated biphenylamide, chloroform has also been generated at the same time, because the medium used for carrying out this reaction is dichloroethane, chloroform just remains in dichloroethane like this. However, dichloroethane containing chloroform cannot be directly used in the Friedel-Crafts reaction between biphenyl and trichloroacetyl chloride, and the reaction medium after each batch of chloroform reaction must be separated and purified, which obviously increases the 4-linkage Production cost of benzonitrile

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