Prepn. of thiourea di:oxide - by oxidn. of thiourea with hydrogen peroxide and alkali metal acetate as stabiliser

摘要

Thiourea is oxidised with hydrogen peroxide to form thiourea dioxide (I) in the presence of an alkali metal acetate as stabiliser. The acetate is pref. that of sodium or potassium, 2-15% by wt. being incorporated. The thiourea is oxidised as a 13-20% aq. soln. or a 40-50% suspension. This is cooled to 0-2 deg.C and 34-50% aq. H2O2 added. The mixt. is kept at 5-30 deg.C for 30 to 90 mins. It is then cooled and filtered to give (I). The mother liquors are recycled. (I) is used as a clarifying decolouriser in the textile industry, and as an antioxidant for the stabilisation of perchloroethylene. It is also used in organic syntheses and in the pharmaceutical industry. The process is simpler to carry out than prior art methods and is safer. It also gives better yields.