Method for preparing 2,2'-(1,2-Ethenediyldi-4,1-phenylene)bisbenzoxazole

Abstract

The invention discloses a method for preparing 2,2'-(1,2-Ethenediyldi-4,1-phenylene)bisbenzoxazole, which is improvement on the prior preparation method. The method is implemented by the steps of condensation, vulcanization, washing and the like. The reaction temperature is raised, so vulcanization reaction lasts for 3 hours or so, belongs to an instantaneous reaction, and can be immediately finished after the addition of sulfur is finished; and the total adding amount of the sulfur is far lower than the theoretical consumption, so the unreacted sulfur does not exist in a reaction system, few byproducts are produced, and a 0B-1 product with better quality can be obtained by washing the obtained product by using a proper amount of dimethylbenzene solvent. Unreacted 4-methyl can be used for next reaction after being recovered, but the 0B-1 product can meet the demands of customers after being washed by dimethylbenzene and water. The 2,2'-(1,2-Ethenediyldi-4,1-phenylene)bisbenzoxazole can be used as a fluorescent whitening agent in the ingredients of plastic, coatings, road marking paint and the like.

Description

technical field [0001] The invention relates to the field of preparation of chemical raw materials, in particular to a method for preparing a fluorescent whitening agent, in particular to a method for preparing 2,2-(4,4-distyryl)bisbenzoxazole. Background technique [0002] 2,2-(4,4-Distyryl)bisbenzoxazole, also known as fluorescent whitening agent 0B-1, is used as a compounding raw material for plastics, paints, road marking paints, etc., for whitening. In the prior art, its preparation method is carried out in two steps through condensation reaction and vulcanization reaction, and the specific operations are: [0003] Mix methylbenzoic acid and o-aminophenol in the reaction kettle, under the action of the solvent xylene as a detergent, first react to generate 4-methylbenzoxazole, and then mix 4-methylbenzoxazole under vacuum And oxazole out of storage. [0004] Take 4-methylbenzoxazole and put it into a vulcanization kettle, add 2 times the weight of sulfur at one t...

AI Technical Summary

Problems solved by technology

[0007] (1) Excessive sulfur was added during the processing, and the sulfur could not fully participate in the reaction. After being treated with a solvent, there was still a large amount of solid waste of sulfur slag, which was difficult to handle;

[0008] ⑵The reaction temperature is between 230~260℃, the reaction time is long, usually about 24 hours per batch, and the production efficiency is low

[0009] (3) After the reaction is completed, there are relatively complex by-products in the reaction materials, which need to be treated with a large amount of organic solvents, which leads to increased consumption of organic solvents and requires Large investment in processing equipment

[0010] ⑷ The quality of the 0B-1 product obtained from the reaction usually cannot meet the user's requirements, and decolorization, refining and post-treatment are required, which not only reduces the product yield, but also consumes a large amount of solvent , the number of equipment increases, and the production cost increases by 10,000 yuan / ton

[0011] (5) Due to the long reaction time, the concentration of the by-product hydrogen sulfide gas is low, which increases the difficulty of recovering hydrogen sulfide gas, resulting in an increase in the number of recovery equipment and a relatively high investment Large, and the processing effect is not ideal

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