Patent GB-432955-A (GB)
Title: Improvements in or relating to the preparation of halogen phenols
IPC: C07C39/28
Filed: 1933-10-28
Abstract: Monohalogen - monophenols containing two or three alkyl or cycloalkyl hydrocarbon substituents, the total number of carbon atoms in the hydrocarbon substituents being at least five, are prepared by (1) halogenating the appropriate phenol, (2) introducing a hydrocarbon radicle, by treatment either with the corresponding halide or alcohol, into the appropriate phenol, either before or after halogenation, (3) reacting upon the appropriate phenol with an acyl halide, forming the ketone by rearrangement, and reducing the ketone to the corresponding hydrocarbon radicle, the product being halogenated if necessary. The products usually employed in aqueous solution, possess bactericidal properties.  According to the examples, (1) 3-methyl-6-sec-butyl-4-chlorophenol is prepared by heating 3-methyl-4-chlorophenol with sec-butyl bromide in the presence of zinc chloride; the use of an amyl alcohol or n-octyl alcohol in its presence of sulphuric acid, zinc chloride, ferric chloride or aluminium chloride, gives rise to 3-methyl-6-amyl-4-chlorophenol and 3-methyl-6-sec-octyl-4-chlorophenol respectively; (2) 2-isopropyl-3 : 5-dimethyl-4-chlorophenol results from the interaction of 3 : 5-dimethyl-4-chlorophenol with isopropyl alcohol in the presence of sulphuric acid; the use of a butyl alcohol produces a butyl-dimethyl-chlorophenol, iodo- and bromo-xylenols may also be used as starting materials; (3) p-ethylphenol is treated with propionyl chloride, the resulting ethyl-phenyl propionate heated with aluminium chloride to give 5-ethyl-2-hydroxypropiophenone, the latter reduced to 4-ethyl-2-propyl-phenol by the Clemmensen method, and finally chlorinated with sulphuryl chloride forming 2-propyl-4-ethyl-6-chlorophenol; 2-methyl-4-chloro-6-butyl-phenol is similarly prepared using p-chloro-o-cresol and butyryl chloride; (4) 2-ethyl-3-methyl-6-isopropyl-4-chlorophenol is obtained by treating p-chlorothymol with acetyl chloride, heating the ester with aluminium chloride to give 6-methyl-3-isopropyl-5-chloro-2-hydroxyacetophenone and reducing with zinc amalgam and hydrochloric acid; bromo- or iodo-thymol or halogenated carvacrols may be used as starting material and propionyl chloride as the esterifying agent, giving rise to the corresponding bromo- and iodo-phenols.  The introduction of an alkyl or cycloalkyl radicle into a phenol containing two hydrocarbon radicles, e.g. sym-m-xylenol, is also described.  The samples furnished under Sect. 2 (5) consist of (1) 4-n-propyl-3 : 5-dimethyl-2-bromo-phenol, prepared by treating sym-m-xylenol with propionyl chloride, heating the resulting propionate with aluminium chloride to give the ketone, reducing with zinc amalgam and hydrochloric acid to 4-n-propyl-3 : 5-dimethylphenol and finally brominating with bromine in glacial acetic acid; (2) 2-cyclohexyl-3 : 5-dimethyl-4-chlorophenol, obtained by heating p-chloro-sym-m-xylenol with cyclo-hexanol in the presence of zinc chloride; (3) o-iodo-p-methyl-o-n-butylphenol, prepared by treating p-methyl-o-n-butyl-phenol with iodine in potassium iodide.  The Specification as open to inspection under Sect. 91 also describes products containing an aralkyl group and refers to the production of 3 - methyl - 6 - phenylethyl - 4 - chlorophenol by treating the corresponding halogenphenol with phenylacetyl chloride, and reducing the resulting ketone.  This subject-matter does not appear in the Specification as accepted.