1957 年 77 巻 9 号 p. 982-984
de Smet obtained the corresponding disulfide from haloarenesulfonyl chloride by reduction with palladium catalyst and reported that there was no formation of a further reduced thiol because the thiol is a catalyst poison. Anticipating the formation of bisaminophenyl disulfide by the catalytic reduction of bisnitrophenyl disulfide, bis(2-nitrophenyl) (I), bis(3-nitrophenyl) (II), and bis(4-nitrophenyl) (III) disulfides were submitted to catalytic reduction with platinum oxide as a catalyst. The corresponding diamino compound was obtained quantitatively from (II), but (I) and (III) were resistant to reduction. Only when the amount of platinum was increased and the reaction time prolonged, (I) afforded the diamino compound and a fair amount of the thiol, while (III) afforded only the thiol compound. When the amount of hydrogen absorbed was reduced to around 1/6, (I) afforded the diamino compound and a minute amount of the thiol and (III) a fair amount of the thiol with the diamino compound. From these facts, it was concluded that, in this reduction, the nitro group is preferentially reduced and the position of the amino group so formed affects the reducibility of the -S-S- bond and that the catalyst-poison effect of the SH group, as pointed out by de Smet, becomes weak according to the position of the substituent.