Imidazolium dichromate alcohols

The oxidative potency of dichromates and chlorochromates decreases under less acidic conditions. This is so, for example, when a less acidic ammonium salt is included as counter-ion of a dichromate or chlorochromate anion. Thus, a number of ammonium dichromates and chlorochromates possessing a milder oxidative potency has been described with the specific purpose of allowing very selective oxidations of unsaturated alcohols in the presence of saturated ones. These selective dichromates and chlorochromates include bis(benzyltriethylammonium)dichromate,135 tetramethylethy-lenediammonium dichromate (TMEDADC),136 imidazolium dichromate (IDC),137 N, A -dimeth y I a m i n o py r id i n i u m chlorochromate (DMAPCC),138 l-(benzoylamino)-3-methylimidazolium chlorochromate (BAMICC)139 and butyltriphenylphosphonium chlorochromate (BTPPCC).140... 

Oxidation of several primary aliphatic alcohols with potassium dichromate, pyri-dinium dichromate, quinolinium dichromate (QDC), imidazolium dichromate, nico-tinium dichromate, isonicotinium dichromate, pyridinium fluorochromate (PFC), quinolinium fluorochromate, imidazolium fluorochromate, pyridinium chlorochromate (PCC), quinolinium chlorochromate (QCC), and pyridinium bromochromate (PBC), in aqueous acetic acid and in the presence of perchloric acid, showed similar kinetics. The values of the reaction constants did not differ significantly, indicating operation of a common mechanism.1... 

Imidazolium dichromate is a selective oxidant for allylic and benzylic hydroxy groups. (Allylic alcohols are oxidized faster than benzylic alcohols.) The selectivity over saturate alcohols is similar to that of 4-(dimethylamino)pyridinium chlorochromate. DMF is recommended as the solvent for oxidations, since it appears that the choice of solvent is critical to obtaining high yields. This reagent has also been observed to cause some ( )/(Z)-isomerization during the oxidation of allylic alcohols. 

The oxalic acid-catalysed oxidation of Af,a-diphenylnitrones by imidazolium dichromate (IDC) is first order in the nitrone, IDC, and oxalic acid. A positive fractional order was obtained with respect to acidity. A mechanism involving the protonated nitrone as a reactive species has been proposed. Oxidation of substituted phenols with isonico-tinium dichromate in the presence of oxalic acid is first order in the reductant and oxidant but showed a fractional order in oxalic acid the Hammett plot is downward concave. Activation parameters have been determined and a mechanism has been proposed. The oxidation of some secondary alcohols," aliphatic aldehydes, and three lower oxyacids of... 

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See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ , ]

See also in sourсe #XX -- [ , ]

See also in sourсe #XX -- [ ]

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