REDOX REACTIONS OF ANTIMONY(III) O,O-DISUBSTITUTED PHOSPHORODITHIOATES WITH FERRIC CHLORIDE

The reaction of antimony(III) tris-(O,O-diethylphosphorodithioate) with three equivalents of ferric chloride in ether solution has been found to give ferrous chloride, bis-(O,O-diethylthiophosphoryl) disulfide and dichloroantimony O,O-diethyl phosphorodithioate as the major products. However, a relatively low yield of bis-(O,O-diethylthiophosphoryl) trisulfide was also obtained. The structures of these products were established by independent syntheses. Several additional antimony(III) tris-(O,O-disubstituted phosphorodithioates) were prepared, and the major organic product obtained by reaction of each of these compounds with three equivalents of ferric chloride was the corresponding bis-(O,O-disubstituted thiophosphoryl) disulfide. A mechanism for this reaction has been suggested, and evidence in support of the mechanism has been presented. The various antimony(III) tris-(O,O-dialkyl phosphorodithioates) are passivating agents used in petroleum refining. The results reported in this and in our previous papers indicate that such compounds undergo a variety of reactions with components of crude petroleum prior to the ultimate pyrolysis reactions which occur in the fluid catalytic cracking process.