Patent GB-782421-A (GB)
Title: Production of bis(hydroxyphenyl) alkanes
IPC: C07C37/20
Filed: 1954-08-23
Abstract: Phenol-aldehyde and phenol-ketone resinous condensation products are obtained, together with bis(hydroxyphenyl) alkanes, when phenol or an alkyl- or chloro-substituted monohydric phenol having at least two reactive positions on the benzene ring is reacted with a substantially stoichiometric amount or more of a water-soluble saturated aliphatic aldehyde or ketone in the presence of aqueous mineral acid of normality at least 0.01 N, the amount of phenol present in the reaction mixture being not in excess of its solubility in the acid solution, and the acid solution comprising 95 per cent or more by volume of the reaction mixture.  A mixture of resinous condensation products and bis(hydroxyphenyl) alkanes is precipitated from the aqueous acid as an oily to viscous organic phase and is separated therefrom. Phenols specified are phenol, m-, p- and o-cresol, 2 : 3-, 2 : 5-, and 3 : 4-xylenol, p-tert.-butyl phenol and o-, p- and m-chlorophenol; aldehydes and ketones specified are formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, iso - butyraldehyde, acetone, methyl ethyl ketone and diethyl ketone. Mineral acids specified are hydrochloric acid sulphuric acid.  In a specific embodiment, phenol is condensed with formaldehyde to form an oily phase comprising dihydroxydiphenylmethanes with higher molecular-weight phenolformaldehyde condensation products and containing 4 : 41-dihydroxy-diphenylmethane as a solid phase which may be removed by filtration or centrifugation.  The viscosity of the oil layer may be reduced before removal of the 4 : 41-isomer by addition of water, aqueous acetic acid or aqueous methanol.  In a modification, the process is conducted continuously by continuously adding the monohydric phenol and aldehyde or ketone in substantially stoichiometric proportions to the aqueous mineral acid at such a rate that the solubility of the phenol in the aqueous acid is not exceeded and at a rate substantially equivalent to the rate at which the products are formed and continuously withdrawing the products.  The concentration of the aqueous acid is maintained by adding additional acid or by selecting the reaction temperature and original acid concentration so that the water formed by the condensation and any water introduced with the reactants is absorbed in the organic product layer and removed therewith to maintain a water balance. Water balance conditions for phenol and formaldehyde in the presence of hydrochloric acid are given.  In examples, phenol and formalin are continuously reacted in the presence of aqueous hydrochloric acid. Reference has been directed by the Comptroller to Specification 711,122, [Group IV (b)]ALSO:Bis - (hydroxyphenyl) alkanes having the hydroxyphenyl groups attached to the same carbon atom of the alkane are prepared by reacting phenol or an alkyl- or chloro-substituted monohydric phenol having at least two reactive positions on the benzene ring with a substantially stoichiometric amount or more of a water-soluble saturated aliphatic aldehyde or ketone in the presence of aqueous mineral acid of normality at least 0.01 N, the amount of phenol present in the reaction mixture being not in excess of its solubility in the acid solution, and the acid solution comprising 95 per cent or more by volume of the reaction mixture.  The mixture of isomeric bis-(hydroxyphenyl) alkanes which is precipitated from the aqueous acid as an oily to viscous organic phase is then separated therefrom.  Phenols specified are phenol, m-, p- and o-cresol, 2:3-, 2:5-, and 3:4-xylenol, p-tert.-butyl phenol and o-, p- and m-chlorophenol; aldehydes and ketones specified are formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, iso-butyraldehyde, acetone, methyl ethyl ketone, and diethyl ketone.  Mineral acids specified are hydrochloric and sulphuric acid.  In a specific embodiment, phenol is condensed with formaldehyde to form an oily organic layer comprising 2:21-and 2:41-dihydroxy - diphenylmethanes together with higher molecular-weight phenol-formaldehyde condensation products and containing 4:41-dihydroxy-diphenyl-methane as a solid phase which may be isolated by filtration or centrifugation of the oil layer. The viscosity of the oil layer may be reduced by addition of water, aqueous acetic acid or aqueous methanol before removal of the 4:41-isomer.  In a modification, the process is conducted continuously by continuously adding the monohydric phenol and the aldehyde or ketone in substantially stoichiometric proportions to the aqueous mineral acid at such a rate that the solubility of the phenol in the aqueous acid is not exceeded and at a rate substantially equivalent to the rate at which the bis-(hydroxyphenyl) alkanes are formed and continuously withdrawing the products.  The concentration of the aqueous acid is maintained by adding additional acid or by selecting the reaction temperature and original acid concentration so that the water formed by the condensation and any water introduced with the reactants is absorbed in the organic product layer and removed therewith to maintain a water balance.  Water balance conditions for phenol and formaldehyde in the presence of hydrochloric acid are given.  In examples, phenol and formalin are continuously reacted in the presence of aqueous hydrochloric acid to form 4:41-dihydroxy-diphenylmethane and an oil phase comprising 2:21-, 2:41- and 4:41-dihydroxy-diphenylmethanes and higher molecular-weight condensation products.  Reference has been directed by the Comptroller to Specification 711,122.