PURPOSE: To obtain substd. phenols by heating a phenol having a secondary or tertiary alkyl at o-position in the presence of an acid catalyst such as alkali metal hydrogensulfates or the like to a temperature of above the melting point to remove the alkyl group.
CONSTITUTION: A compound of formula I (X is C3-12 secondary or tertiary alkyl, R1-R4 are each H or optionally substd. C1-12 alkyl, C2-12 alkenyl or alkynyl) is melted. An alkali metal hydrogensulfate (preferably anhydrous sodium or potassium hydrogensulfate) is added while stirring the melt and the temperature is raised to 120-70°C for 2-6 hours and the pressure in the reactor is reduced to 10-300 mbav to remove the gaseous formed products. The melt is cooled to give a compound of formula II with high purity. Among the compounds of formula I is especially preferred a compound of formula III. The compound of formula II is useful as a starting material for preparing a benzotriazole series of UV absorbents.
RONARUDO ZARAATE
RUDORUFU SHIYUBUABE
