Phenol‐formaldehyde and allied resins. III. Further syntheses of resole molecules

Attempts to extend the lithium‐exchange reaction for the synthesis of carboxydihydroxydiphenyl‐methanes for subsequent reduction to resoles indicated that this method was likely to prove of very limited application. Attention was therefore directed to the syntheses of carboxy‐derivatives of dihydroxydiphenylmethanes by means of side‐chain oxidation of nuclear‐methyl‐substituted dimethoxydi‐phenylmethanes, direct carbonation of dihydroxydiphenylmethanes, and condensation of bromomethyl‐salicylic acid with phenols. Seven new resoles have been synthesized by lithium aluminium hydride reduction of carboxydihydroxydiphenylmethanes thus obtained and by further application of the method of halogen‐blocking and subsequent dehalogenation. 5‐Hydroxymethyl‐2:2′‐dihydroxydiphenylmethane and 3‐hydroxymethyl‐4:4′‐dihydroxydiphenylmethane were synthesized by oxidation of 2:2′‐dimethoxy‐5‐methyldiphenylmethane and 4:4′‐dimethoxy‐3‐methylbenzophenone respectively, followed by demethylation, Clemmensen reduction of the carboxydihydroxybenzophenones and lithium aluminium hydride reduction of the resulting carboxydihydroxydiphenylmethanes. 3:3′‐Bishydroxymethyl‐4:4′‐dihydroxydiphenylmethane and 3‐hydroxymethyl‐2:2′‐dihydroxydiphenylmethane were synthesized by carbonation of 4:4′‐dihydroxydiphenylmethane and 2:2′‐dihydroxydiphenylmethane respectively and subsequent lithium aluminium hydride reduction. 2:2′‐Dihydroxy‐3:3′‐bishydroxymethyldiphenylmethane was synthesized from 5:5′‐dibromo‐2:2′‐dihydroxydiphenylmethane by way of 5:5′‐dibromo‐2:2′‐dihydroxy‐3:3′‐bishydroxymethyldiphenylmethane and dehalogenation of the latter by palladium and hydrogen. 3‐Hydroxymethyl‐4:2′‐dihydroxy‐5′‐methyldiphenylmethane was synthesized by condensation of 4‐bromomethyl‐2‐carboxyphenol with p‐cresol and subsequent reduction of the resulting 3‐carboxy‐4:2′‐dihydroxy‐5′‐methyldiphenylmethane, and application of this reaction to p‐bromophenol with subsequent dehalogenation of the 5′‐bromo‐3‐carboxy‐4:2′‐dihydroxy‐derivative furnished a synthesis of 4:2′‐dihydroxy‐3‐hydroxymethyldiphenylmethane.