METHOD OF OBTAINING 2-ARYL-5-(2-CARBOXYVINYL)-1,3,4-OXADIAZOLES Russian patent published in 2015 - IPC C07D271/10 

FIELD: chemistry.

SUBSTANCE: invention relates to field of obtaining 2-aryl-5-(2-carboxyvinyl)-1,3,4-oxadiazoles, which possess properties of organic luminophores and semiconductors and can be potentially used in industry in creation of fluorescent paints, plastic scintillators, electroconductive layers of organic light diodes, as well as in active media of liquid lasers. Method of obtaining 2-aryl-5-(2-carboxyvinyl)-1,3,4-oxadiazoles includes two stages, separation of target products by pouring reaction mixture into water with ice, filtration of sediment, and re-crystallisation. At the first stage acylation of hydrizide of aromatic carboxylic acid with maleic anhydride is carried out in icy acetic acid at room temperature, with molar ratio hydrizide:maleic anhydride from 1:1 to 1:1.5 for 5-30 minutes. (Z)-4-(N'-aroylhydrazino)-4-oxo-2-butenic acid, precipitated from reaction mixture in form of deposit, is filtered, washed with icy acetic acid, dried and at second stage subjected to cyclisation in aprotic dipolar solvent with application of dehydrating reagent, with molar ratio reagent: (Z)-4-(N'-aroylhydrazino)-4-oxo-2-butenic acid from 1:1 to 3:1 for 10-90 minutes, at temperature from 15 to 50°C, with obtaining mixture of isomers of 2-aryl-5-(2-carboxyvinyl)-1,3,4-oxadiazoles in form of solution in applied solvent and with further separation of target products. To separate target products obtained mixture of isomers is poured into water with ice, with immediate filtration of precipitated deposit - (E)-2-aryl-5-(2-carboxyvinyl)-1,3,4-oxadiazole, remaining filtrate is kept for six or more hours at room or lower temperature with further filtration of (Z)-2- aryl-5-(2-carboxyvinyl)-1,3,4-oxadiazole, precipitated for said time in form of deposit.

EFFECT: obtaining safe and profitable from energy point of view method of compound synthesis.

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