| abstract |
Taking methylparaben and urea as the basic raw materials, the artificial zeolite, silica gel , oxidized The solid-supported phosphoric acid with aluminum, SiO 2 , ZrO 2 or molecular sieve as the carrier is used as a catalyst, and the p-hydroxybenzamide formed by the reaction of methyl p-hydroxybenzoate with urea in an ammonia atmosphere is subjected to in-situ catalytic dehydration at high temperature. Methyl p-hydroxybenzoate and urea are directly prepared to obtain the mixed material containing p-hydroxybenzonitrile, and finally the mixed material containing p-hydroxybenzonitrile obtained by cooling and condensing is rectified by stepwise cooling, so as to be relative to the p-hydroxybenzonitrile. The yield of methyl benzoate is more than 70% by mass to obtain a parahydroxybenzonitrile product with a mass percentage content of more than 97%. |