Preparation of an aqueous solution containing ions of at least manganous

Abstract

This invention relates to the preparation of the subject aqueous solution from a non-bromine manganous salt. More specifically this invention pertains to a critical order of dissolving such salt and elemental bromine and to the use of an anti-oxidant for the manganous ion to prevent its conversion to hydrated manganous dioxide: MnO(OH).sub.2. According to 'A Comprehensive Treatise On Inorganic And Theoretical Chemistry', J. W. Mellor, Vol. XII at pages 189 and 259 (published by Longmans, Green and Co., 1947) hydrated manganous dioxide results from the oxidation of a solution of manganous salt with chlorine, bromine, hypochlorous acid, hydrogen peroxide, etc. Such oxidation of a solution of manganous acetate was specifically mentioned. Such hydrated manganous dioxide is described as a white solid product which upon standing in contact with air becomes a dark brown to black product identified as MnO.sub.2. The same reference at page 381 reports the preparation of manganous bromide by reaction of bromine with a solution of manganous oxide. We have found that the addition of bromine gas or liquid to a stirred aqueous solution containing manganous ions from a source other than manganous bromide caused the formation of a precipitate which contains the previously dissolved manganese component. The same precipitate formed upon addition of manganous acetate tetrahydrate to a stirred aqueous solution of elemental bromine.