To a mixture of 1.48 parts of ethanedithiol and 3.4 parts of triethylamine in
30 ml of benzene is added, with cooling, 5.7 parts of diethoxyphosphinyl
isothiocyanate. After an hour, this mixture is added to 5.7 parts of benzyl
bromide in 25 parts by volume of toluene in several portions over a 10 min
period (mild temperature rise to 29°C). After stirring over night, the mixture
is diluted with more benzene, washed (including dilute sodium hydroxide), and
concentrated to give 10.7 parts of oil. Column chromatography on a total of
150 parts of silica gel yields, on sequential elution with 1:1 carbon
tetrachloride:chloroform, chloroform and 2-10% methanol in chloroform, 4.5
parts (42%) crude product. The 2.0 parts of colorless crystalline of S,S'-
ethylene-S,S'-dibenzyl-diethoxyphosphinylimidodithiocarbonate, melting point
67.5-68.5°C (recrystallization from ether) are obtained.
