Continuous thiourea di:oxide prodn. from thiourea - by oxidn. with hydrogen peroxide in aq. medium

摘要

Prepn. of thiourea dioxide of formula (I) comprises reacting thiourea (II) and H2O2 in aq. soln. in an externally cooled internally stirred reactant. Solid (II) and commercial concn. (pref. 30-70 wt%) H2O2 are continuously supplied to a reactor filled with reaction soln. Mole ratio (II): H2O2 is 1-1.5:1. The obtd. (I) is withdrawn from the reactor as a crystal suspension and recovered by conventional methods. (I) is a strong reducing agent in acid or esp. ammoniacal soln. it can be used e.g. for reducing vat dyes and ketones, as polymerisation catalyst for unsatd. Cpds. as a antioxidant and as a starting material and auxiliary in the prodn. of pharmaceuticals and chemicals. (I) can be prepd. continuously in 90% yield and approx. 98% purity in a reactor of very low specific vol.