| 摘要 |
FIELD: chemistry. ^ SUBSTANCE: invention relates to an improved method for synthesis of 2-acetoxy-5-biphenylcarboxylic acid, involving alkylation by adding p-cresol and an alkylation agent into molten pyrophosphoric acid, heating and holding at temperature while stirring, separation of the hydrocarbon layer, washing to a neutral reaction, drying with calcium chloride and rectification under vacuum of 9-10 mm Hg and temperature 151-156C to obtain 4-methyl-2-cyclohexylphenol and then its dehydrogenation in liquid phase at atmospheric pressure and high temperature on palladium catalysts, with extraction of 5-methyl-2-biphenylol when cooling. Alkylation is carried out at 110-120C. The alkylation agent used is cyclohexane. Dehydrogenation is carried out at 300-350C using palladium catalysts in form of palladium catalysts on carbon. After extraction, the 5-methyl-2-biphenylol is acylated in acetic anhydride in the presence of sulphuric acid to 2-acetoxy-5-methylbiphenyl, with subsequent oxidation of the 2-acetoxy-5-methylbiphenyl in a solution of a mixture of glacial acetic acid and acetic anhydride (1:1) with oxygen at temperature 105-110C in the presence of a soluble cobalt-manganese-bromine catalyst until complete oxidation and extraction of 2-acetoxy-5-biphenylcarboxylic acid crystals from the reaction mixture after cooling. ^ EFFECT: method increases output of the valuable 2-acetoxy-5-biphenylcarboxylic acid monomer and lowers the cost of the process. ^ 2 ex |
