Phenol‐formaldehyde and allied resins VI: Rational synthesis of a ‘cyclic’ tetranuclear p‐cresol novolak

The rational synthesis of the ‘cyclic’ tetranuclear p‐cresol novolak (VIII) from the corresponding resole (VII) which was synthesized from 3‐bromo‐2:2′‐dihydroxy‐5:5′‐dimethyldiphenylmethane (I) has been accomplished in accordance with the scheme given below. A molecular model of the resole (VII) indicated that intramolecular hydrogen bonding of the hydroxyl groups would assist the formation of a configuration which could undergo facile cyclization to give the required novolak (VIII). The infrared absorption spectrum of the ‘cyclic’ tetranuclear novolak showed only the band corresponding to 1:2:4:6‐tetra‐substitution and absence of that due to 1:2:4‐tri‐substitution which was present in the resole (VII). Confirmation of structure was obtained by conversion into a tetra‐acetate which gave a molecular weight determination of the correct order and whose infra‐red absorption spectrum also showed only 1:2:4:6‐tetra‐substitution.