Method for preparing 2,5-bis(5-tert-butyl-2-benzoxazolyl)thiophene

Abstract

The invention discloses a method for preparing 2,5-bis(5-tert-butyl-2-benzoxazolyl)thiophene, which is an improvement on the prior preparation method. The method is realized through condensation, dehydration, distillation and refinement. The method utilizes a vacuum system to realize distillation under reduced pressure during the distillation so as to lower boiling point and save energy sources; trichlorobenzene is not recovered specially any more, and the yield of the trichlorobenzene is improved to 99 percent or so from 89 percent; the method avoids equipment investment used for recovery equipment, and also reduces environmental pollution when the production cost is reduced; and the trichlorobenzene is directly evaporated out, so that the impossibility that an OB product is subjected to high temperature metamorphism and carbonization and cannot be recovered when dissolved into the trichlorobenzene is avoided and the overall yield of a target product is improved. The 2,5-bis(5-tert-butyl-2-benzoxazolyl)thiophene can be used as a fluorescent whitening agent in the ingredients of plastics, coatings, road marking paint and the like.

Description

Technical field [0001] The present invention is the field of chemical raw material preparation, which specifically involves the preparation method of a fluorescent whitening agent 2,5 -dual (5 -olinel 2 -benzopyzole). Background technique [0002] 2,5 -double (5 -benzopyl 2 -benzene and villain), which is a fluorescent whitening agent 0B. It is used as a mixed raw material for plastic, coatings, road label paint, etc. to play a white effect.In the existing technology, the preparation method is to add a mixed solution of trichloropine and toluene to the reactor, and then add 0b acid (ie, moltolone 2,5 -di carboxylic acid), 0b phenol (that is, tortie -neighboring aminophenol)With boric acid, a shrinkage reaction is performed to about 120 ° C. The water generated by the reaction is steamed with toluene together, and the water is placed with a splitter. When the temperature of the reaction material rises above 180 ° C, the toluene steamer, steaming of toluene, steaming, steaming of t...

AI Technical Summary

Problems solved by technology

[0003] (1) The yield of the target product 0B is low, the highest can only reach 85%;

[0004] (2) When trichlorobenzene is recovered, the energy consumption will increase, and a special recovery device should be required; 0B products dissolved in trichlorobenzene will deteriorate and carbonize at high temperature, and cannot is recycled, thereby affecting the overall yield of 0B products

[0005] (3) When carrying out solid-liquid separation, the yield of trichlorobenzene is affected due to the loss of trichlorobenzene; will cause environmental pollution

Images