Polarography of Certain Organic Polysulfides

Organic Polarography

“…The polarographic reduction of disulfides which involved 2 electrons (61) has been compared with the behavior of trisulfides and tetrasulfides (197).…”

Potentiometric Determination of Mercaptans in Presence of Elemental Sulfur

“…For example, Eby (4) showed that tertiary mercaptans could form stable tetrasulfides in presence of an alkaline sulfide solution, whereas n-butyl tetrasulfide was less stable. Work by Karchmer and Walker (7) and Birch, Cullum, and Dean (1) has indicated a difference in the degree to which various organic radicals in polysulfides retain sulfur atoms. Thus the end product in Equation 7 would not necessarily be a trisulfide and the amount of sulfur consumed could be more or less than indicated.…”

“…Thus the end product in Equation 7 would not necessarily be a trisulfide and the amount of sulfur consumed could be more or less than indicated. When R is a normal alkyl, Equation 7 is essentially correct and the organic trisulfide is formed; however, when R is a tertiary alkyl group, such as ieri-amyl or ieri-butyl, the reaction could be 2(iC,S)-+ 3S°+ 2Ag+ -iC4SSSSiC4 + Ag2S (13) when R is a phenyl group the over-all reaction may be 2(»S)-+ S°+ 2Ag+ 0SS0 + Ag2S (14) This is supported by data in Table IV, which show that when a 3 to 1 ratio of ieri-butyl mercaptan sulfur to elemental sulfur is used, the amount of unreacted mercaptan present (after 5 minutes) equals 76.5% (10.46 ml. out of a total of 13.69 ml.…”

Review - Petroleum

“…Earle (37) determined disulfides in petroleum products by reducing to thiols and titrating with silver nitrate after preliminary elimination of the original thiols by reaction with acrylonitrile to form thioethers. Karchmer and Walker (89) studied the polarographic behavior of organic di-, tri-, and tetrasulfides and found that tetrasulfide and trisulfide produced three polarographic waves the last of which may be used to approximate concentration. The intermediate wave of the polysulfide occurred at about the same voltage as elementary sulfur and the presence of the latter in large amounts may be suspected if the polarogram of an unknown shows a ratio greater than 1 for the intermediate to late wave.…”