GB785079A - Improvements in or relating to the preparation of bis(hydroxyaryl) compounds - Google Patents

Abstract

A process for preparing a bis-(hydroxyaryl) compound having the formula <FORM:0785079/IV (a)/1> wherein R1 and R2 represent the same or different saturated or unsaturated monovalent aliphatic, cycloaliphatic, aromatic or heterocyclic radicals with the provision that either R1 or R2 but not both may also represent a hydrogen atom and the symbols Ar and Ar1 represent the same or different aromatic nuclei by the acid catalysed condensation of a phenolic compound comprises reacting said phenolic compound with said carbonylic compound in a mol. ratio of at least 5:1 and in a plurality of successive reaction stages maintained temperatures between about 20 DEG and about 110 DEG C., the reactants introduced into the first reaction stage comprising substantially all of said phenolic compound but only a part of said carbonylic compound and the remainder of said carbonylic compound being introduced into at least one subsequent reaction stage. Suitable phenolic starting material should have at least one replaceable hydrogen attached to a nuclear carbon atom and may have such substituents as alkyl, cycloalkyl, aryl, alkaryl and aralkyl groups, and include phenol, the cresols, xylenols, thymol, carvacrol, 2,4-dimethyl-3-ethylphenol, o- and p-phenylphenol, the naphthols and phenanthrol. The carbonylic starting materials are aldehydes and ketones of the general formula R1R2CO, where R1 represents any aliphatic, cycloaliphatic, aromatic or heterocyclic monovalent radical, e.g. pyridyl and R2 represents a hydrogen atom or a monovalent radical as defined under R1, e.g. dimethyl, dibutyl and methyl amyl ketones, propionylphenone, acetophenone, acetaldehyde, benzaldehyde and acetyl pyridine. Catalysts mentioned include hydrogen chloride, sulphuric, phosphoric, hydrobromic, hydrofluoric, nitric and p-toluene sulphonic acids, dimethyl sulphate, sulphur dioxide, boron trifluoride and complexes thereof, aluminium chloride, sulphonyl chloride and phosgene. Promoters may be employed such as methyl and ethyl mercaptans, thiophenols and mercapto-substituted aliphatic monocarboxylic acids. Solvents mentioned include aromatic hydrocarbons such as xylene, toluene and chlorinated hydrocarbons. 2,21 - Bis - (4 - hydroxyphenyl) propane is obtained by reacting phenol and dimethyl ketone in two reactions in series in the presence of hydrogen chloride and methyl mercaptan, only part of the ketone being introduced into the first reactor and the remainder with the second. In the drawing (not shown) an apparatus comprising two reactors and distillation columns is shown. Specifications 735,215 and 735,216 are referred to.