Process for the production of cyclic ethers of aromatic compounds containing hydroxyl groups

Cyclic ethers of aromatic hydroxy compounds are obtained by reacting substituted or unsubstituted phenols, being unsubstituted in at least one ortho position with respect to a hydroxyl group, with dienes, containing conjugated double bonds, at elevated temperatures in the presence of a phenolate of zinc, aluminium, magnesium, calcium, sodium or lithium. Suitable phenols are, for example, phenol, o-chlorophenol, m-chlorophenol, p-chlorophenol, 2,4-dichlorophenol, o, m, and p - cresol, 3,5 - dimethyl - 4 - chlorophenol, 2-methoxyphenol, a - naphthol, b - naphthol, hydroxyanthracenes and hydroxyphenanthrenes. Suitable dienes are, for example, isoprene, 1,3-butadiene, 2,3-dimethyl-1,3-butadiene and piperylene. It may be desirable to add a stabilizer, e.g. phenthiazine, hydroquinone or an alkylated amine to the mixture. The metal phenolates can be added as such or produced in situ by adding the metal, preferably as powder or shavings, to the mixture. The metal may be amalgamated with mercury by adding a small quantity of a mercury salt. A solvent, e.g. benzene, toluene or xylene, may be used for the reactants. The process is preferably carried out at a temperature of 100-140 DEG C. Examples are given of (a) the reaction between phenol and isoprene to give 2,2-dimethyl chromane, 5 - (3 - methylcrotyl)-2,2,3-trimethyl coumarane, 5-(3-methylcrotyl)-2,3,3,-trimethyl chromane; (b) the production of 6-chloro-2,2-dimethyl chromane from p-chlorophenol and isoprene; (c) the production of 5-chloro-2,3-dimethyl coumarane from p-chlorophenol and butadiene; (d) the production of 6,8-dichloro-2,2 - dimethyl - chromane from 2,4-dichlorophenol and isoprene; (e) the production of 2,2,3,5- and 2,3,3,5-tetramethyl coumarane and 2,2,6-trimethyl chromane from p-cresol and isoprene; (f) the production of 6-chloro-2,2,5,7-tetramethyl-chromane from 3,5-dimethyl-4-chlorophenol and isoprene; (g) the production of 6-chloro-2,2,3-trimethyl chromane from p-chlorophenol and 2,3-dimethyl-1,3-butadiene; and (h) the production of 2,2-dimethyl-5,6-benzochromane from b -naphthol and isoprene. Specifications 776,204 and 798,438 are referred to.