Лако-красочные материалы — производство

Consideration must be given to the possibility of direct intervention by the catalyst in the reaction. Hydrochloric acid is the most interesting case of an acid catalyst, as is ammonia of an alkaline catalyst. When the PF reaction is catalyzed by hydrochloric acid, two mechanisms may come into operation. Vorozhtov has proposed a reaction route that passes through the formation of bischloromethyl ether (Cl-CH2-O-CH2-Cl) [4]. Ziegler has suggested a route through the formation of a chloromethyl alcohol (Cl-CH2-OH) as intermediate [5,6]. The second route appears to be the more probable. Both hypotheses agree that chloromethylphenols are the principal intermediates. The chloromethylphenols have been prepared and isolated by various means. They are highly reactive compounds which, with phenols, form dihydroxydiphenylmethanes and complex methylene-linked multiring polyphenols. Reaction is highly selective and takes place in the para position.