GB991223A - Process for the production of n,n-di(hydroxyaryl) alkanes - Google Patents

Abstract

Alkanes substituted on the same carbon atom with two similar or dissimilar hydroxyaryl groups are prepared by condensing a hydroxyaryl compound with an aldehyde containing 1-10 carbon atoms or with an activated ketone in the presence of a catalyst constituted by a strong organic acid containing no sulphur and in the presence also of an organic diluent which is a solvent for the starting materials. An activated ketone is defined as a ketone having a carbonyl group capable of forming a hydrate. A strong organic acid is defined as an organic acid having a dissociation constant at 25 DEG C. of at least 10-4. Specified aromatic hydroxy compounds are phenols and naphthols which may carry alkyl substitutents of 1-5 carbon atoms, e.g. 2 - isopropylphenol, 2 - tert. - butylphenol, 2 - methyl - 6 - isopropylphenol, 2 - methyl- 6 - tert. - butylphenol, 2,6 - di - tert. - butylphenol and 2,6-diisopropylphenol. The preferred aldehyde is formaldehyde, which may be taken as trioxymethylene. A specified ketone is trichloracetone. Specified catalysts include formic, acetic and propionic acids, mono-, di- and tri-chloro- and -fluoro-acetic acids, haloformic acids and chloro-propionic and butyric acids. The organic diluent may be tetrahydrofuran or dioxane, or the catalysts may be present in sufficient proportion to act as a diluent. The reaction may be effected at 50-150 DEG C. and at atmospheric, reduced or raised pressure. The starting materials may be substantially or completely anhydrous. Examples are given of the preparation of 3,31,5,51-tetra - tert. - butyl - 4,41 -dihydroxydiphenyl-methane by condensing 2.6-di-tert.-butylphenol with trioxymethylene in the presence of formic acid.