Methacrylic acid, ester or nitrile prepn. - from propionic acid, esters or nitrile by alumina-catalysed reaction with methylal

摘要

Methacrylic acid or its esters or nitrile are prepd. by reacting prepionic acid or its esters or nitrile with methylal, esp. at 300-400 degrees C, in the presence of a catalyst consisting of or contg. Al2O3 which was preheated to 600 degrees C. Propionic acid conversion decreases whereas selectivity increases with higher pretreatment temp. of Al2O3, e.g., at 600 degrees C and 1100 degrees C pretreatment temps., coversion is 47.3% and 12.95% respectively and selectivity is 12.3% and 44.8% respectively. A reaction temp. increase from 400 degrees C to 450 degrees C doubles conversion but reduces selectivity by 1/3.