Chemical method for synthesizing camphor from turpentine
A-pinene obtained by vacuum fractionation of premium turpentine is isomerized to camphene with metatitanic acid catalyst. The pure camphene (freezing point above 44°C) obtained by fractionation is esterified with glacial acetic acid to form isobornyl acetate. Fractional distillation and purification until the ester content reaches more than 95%, pressure saponification with sodium hydroxide aqueous solution of about 45% concentration and an appropriate amount of xylene, add an appropriate amount of xylene as a solvent after the reaction is completed, stand for stratification, and after separating and removing sodium acetate, Washed with water until neutral to obtain isoborneol xylene solution. Using basic carbonate ketone [CuCO3•Cu(OH)2] as a catalyst, isoborneol was dehydrogenated at 180℃ and xylene was evaporated, and finally the synthetic camphor was prepared by blowing sublimation at 212℃.
The specifications of China's synthetic camphor are divided into two categories: industrial grade and pharmaceutical grade. Industrial grade camphor powder has a melting point of 165°C or more and a brain content of more than 96%; the medicinal grade can meet the specifications of the pharmacopoeia of various countries.
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