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Tris 12-tungstophosphate

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). [Pg.362]

Several compounds of tungsten, which is a transition metal closely related to molybdenum, are able to catalyze the selective oxidation of secondary alcohols with hydrogen peroxide as secondary oxidant. These include tris(cetylpyridinium) 12-tungstophosphate,33 peroxotungstopho-sphate (PCWP)34 and Na2W04 in the presence of a phase transfer catalyst.35 Tungstophosphoric acid is able to catalyze the selective oxidation of secondary alcohols in the presence of ferric nitrate as secondary oxidant.36... [Pg.346]


See other pages where Tris 12-tungstophosphate is mentioned: [Pg.476]    [Pg.576]    [Pg.26]    [Pg.63]   


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Tungstophosphates

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