Abstract 3, 9-Dichloro-2, 4, 8, 10-tetraoxa-3, 9-diphosphaspiro [5. 5] undecane-3, 9-disulfide (I), has been synthesized by treating a dimethylacetamide solution of 2, 4, 8, 10-tetraoxa-3, 9- diphosphaspiro [5. 5] undecane-3, 9-disulfide (III) with carbon tetrachloride. A number of other known methods for converting dialkyl phosphorothioites to thiophosphorochloridates were also applied to III, but all failed to produce I. Chlorination of either I or III gave an ...