Preparation of a dithiodibenzoate, dithiocarbonate, trithiocarbonate mixture

Abstract

A method for producing a mixture of a dithiodibenzoate, a dithiocarbonate, and a trithiocarbonate, is disclosed. The method includes diazotizing an amine having the formula ##STR1## where R is hydrogen, or an alkyl group having not more than 4 carbon atoms, and coupling the resulting diazonium with at least 1 gram-mole of carbon disulfide per gram-mole of the diazonium in the presence of a copper catalyst. Under appropriate conditions, which include a reaction temperature in the range of 10.degree.-32.degree. C., sufficient time for full coupling to occur, and dissolving of the CS.sub.2 in a suitable water-miscible solvent such as methanol, coupling to said mixture readily occurs. The coupling products are then dissolved and removed by use of a water-immiscible inert solvent. According to the invention, the surface area of copper must be at least 2000 square centimeters per gram-mole of the diazonium reactant to adequately catalyze coupling; larger areas up to substantially 3000 square centimeters per gram-mole are preferred, a greater area than 3000 square centimeters having no effect. The products of the coupling reaction can be converted to saccharin or 2,2'-dithiodibenzoic acid, useful as an intermediate in the production of compounds such as 1,2-benzisothiazoline-3-one, a fungicide and bactericide.

Dependencies are inferred from the claim text.