Chemical process for the extraction of 2-hydroxy pyridine derivatives, 2-hydroxyquinoline, and 2-hydroxybenzothiazole

Abstract

A process for extracting from aqueous solution the alkali metal or calcium salt of a halo or haloalkyl substituted 2-hydroxypyridine, or a 2-hydroxyquinoline or 2-hydroxybenzothiazole which comprises contacting an aqueous alkaline or neutral solution of the alkali metal or calcium salt, in which is dissolved an alkali metal fluoride, chloride, bromide, hydroxide, sulphate, sulphite, cyanate, cyanide, thiocyanate, thiosulphate, sulphide, phosphate, hydrogen phosphate, carbonate, bicarbonate, borate, chlorate, hypochlorite, perchlorate, nitrite, chromate, dichromate or permanganate or calcium chloride, bromide, nitrate, nitrite, chlorate, hypochlorite, perchlorate, thiocyanate, thiosulphate, chromate, dichtromate or permanganate, with a partially water-miscible organic solvent so as to transfer aqueous solution of the alkali metal or calcium salt of the 2-hydroxypyridine, 2-hydroxyquinoline or 2-hydroxybenzothiasole into the solvent whilst retaining separate aqueous and solvent phases, and thereafter separating the solvent phase containing the alkali metal or calcium salt and water from the aqueous phase, the ratio of solvent to water in the separated solvent phase being from 0.5:1 to 10:1 w/w.