GB389517A - Improvements in the removal of pyridine or other nitrogenous bases from phenols - Google Patents

Abstract

Basic substances containing nitrogen such as ammonia, aniline, pyridine and its homologues and quinoline are removed from phenols containing them by converting the basic substances into their salts with mineral acids or difficultly volatile organic acids the phenols then being distilled off. Suitable acids are sulphuric, phosphoric, hydrochloric, hydrobromic and benzene or naphthalene sulphonic acids. The basic salts may be recovered by extracting the residues of the distillation with water and the base may be liberated by means of basic solutions such as caustic soda solutions or milk of lime or by passing in ammonia. In examples, (1) the crude phenol prepared according to Specification 359,681 is mixed with sulphuric acid and distilled under reduced pressure. From the residue further phenol may be recovered by dissolving the salts of basic substances by water and the crude bases may be recovered from the solution by passing aqueous ammonia into the solution. (2) A crude phenol obtained by extracting low temperature carbonization liquids with tricresyl phosphate is treated with sulphuric acid. (3) A mixture of phenol and pyridine is distilled under reduced pressure in the presence of benzene-sulphonic acid. (4) Phenols obtained by the extraction by benzene of waste water used for washing coke oven gases is distilled under reduced pressure with phosphoric acid.