Sulfonium ion perchlorate

Protonic initiation is also the end result of a large number of other initiating systems. Strong acids are generated in situ by a variety of different chemistries (6). These include initiation by carbenium ions, eg, trityl or diazonium salts (151) by an electric current in the presence of a quartenary ammonium salt (152) by halonium, triaryl sulfonium, and triaryl selenonium salts with uv irradiation (153—155) by mercuric perchlorate, nitrosyl hexafluorophosphate, or nitryl hexafluorophosphate (156) and by interaction of free radicals with certain metal salts (157). Reports of "new" initiating systems are often the result of such secondary reactions. Other reports suggest standard polymerization processes with perhaps novel anions. These latter include (Tf)4Al (158) heteropoly acids, eg, tungstophosphate anion (159,160) transition-metal-based systems, eg, Pt (161) or rare earths (162) and numerous systems based on tri flic acid (158,163—166). Coordination polymerization of THF may be in a different class (167). 

Some 5-(alkyloxy)thianthrenium perchlorates (15) have been prepared in which the alkyl group may be primary or secondary. Reaction with iodide ions may result in 5 n2 reaction at the alkyl group or NAr reaction at the sulfonium sulfur atom leading to the formation of thianthrene. ... 

Protonic acids are efficient initiators for the polymerization of both sulfides and amines. The polymerization of thiiranes initiated with perchloric acid proceeds without induction periods. Induction periods are present, however, with methyl fluorosulfonate initiator 11). Secondary sulfonium salts are more reactive than tertiary ones (the opposite is true with oxonium ions)12) and induce rapid polymerization ... 

Unsym. sulfonium perchlorates can be efficiently prepared from sulfides and alcohols with perchloric acid. The non-nucleo-philic nature of the perchlorate ion as compared to the halide ion makes the process irreversible and avoids alkyl interchange... 

A mixture of di-n-butyl sulfide, 70%-perchloric acid, and benzyl alcohol heated 4 hrs. at 70-80 benzyldi-(n-butyl) sulfonium perchlorate. Y 83.5%.—The non-nucleophilic nature of perchlorate ion as compared to halide ion makes the process irreversible and thus avoids alkyl interchange. F. e., also with azeotropic removal of water, s. T. W. Milligan and B. G. Minor, J. Org. Ghem. 28, 235 (1963). 

---