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Pertungstic acid

Hydroxylation by hydrogen peroxide in t-butyl alcohol solution is catalyzed by osmium tetroxide. The catalyst is volatile and dangerous to handle but is conveniently used in a solution of the tertiary alcohol. The yields of diols are usually low (30-60%), and the process has not been adapted to large-scale preparations. In contrast to hydroxylation by performic acid, this procedure leads to cis addition of the two hydroxyl groups to the double bond. An extensive study of other catalysts has been made. Some catalysts, e.g., selenium dioxide and pertungstic acid, catalyze addition in the trans direction. Hydroxylation of cyclopentadiene takes place in the 1,4-positions to give 2-cyclopenten-l,4-diol. ... [Pg.95]

Pertungstic acid and its derivatives are little known compounds formed by the action of hydrogen peroxide on tungstic acid or the tungstates, Usually at the boiling temperature. They are easily soluble, unstable, and difficult to purify. The valence of tungsten in these compounds appears to be higher than six. [Pg.289]

Model experiments (192, 193) on a-ethylcrotonic acid (structure CLXVIII strongly supported but not proved unequivocaUy) served as a guide for the homolog (CLXVII). TroTis-dihydroxylation of o-ethyl-crotonic acid using performic acid or pertungstic acid yielded erythro-... [Pg.76]

The relative configurations at the asymmetric carbons were decided through the stereospecific synthesis of ( )-viridifloric acid, again on the assumption of CLXVIl as the structure of the precursor a-isopro-pylcrotonic acid. Traws-dihydroxylation of a-isopropylcrotonic acid was effected by Dry and Warren (184) by conversion with perbenzoic acid to the epoxide (not isolated), which was hydrolyzed with aqueous sulfuric acid to ( )-er2/phenacyl ester, m.p. 123-124°) by pertungstic acid oxidation of a-isopropylcrotonic acid. The... [Pg.77]

Ci2H,5N203]- H3C CH3 1 [Tn-0 H3C CH3 6.7.8 Isoindol Oxidation of corresp. amine with pertungstic acid/ CH2CI2 inyl-2-ox EPR/ 300 yls N 1.40 79Gril )... [Pg.308]

Oxidation of corresp. amine with pertungstic acid/... [Pg.385]

See other pages where Pertungstic acid is mentioned: [Pg.184]    [Pg.52]    [Pg.52]    [Pg.184]    [Pg.52]    [Pg.52]    [Pg.394]    [Pg.29]    [Pg.70]    [Pg.82]    [Pg.223]    [Pg.184]    [Pg.52]    [Pg.52]    [Pg.184]    [Pg.52]    [Pg.52]    [Pg.394]    [Pg.29]    [Pg.70]    [Pg.82]    [Pg.223]    [Pg.454]    [Pg.115]    [Pg.242]    [Pg.139]    [Pg.141]    [Pg.141]    [Pg.142]    [Pg.224]   
See also in sourсe #XX -- [ Pg.139 , Pg.140 , Pg.141 ]



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