Imidazolium dichromate, oxidation with

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... 

The oxidation of meta- and para-substituted anilines with imidazolium fluorochro-mate (IFC)18 and nicotinium dichromate (NDC),19 in several organic solvents, in the presence of p-toluenesulfonic acid (TsOH) is first order in the oxidant and TsOH and is zero order with respect to substrate. A correlation of rate data in different solvents with Kamlet-Taft solvatochromic parameters suggests that the specific solute-solvent interactions play a major role in governing the reactivity, and the observed solvent effects have been explained on the basis of solute-solvent complexation. The oxidation rates with NDC exhibited negative reaction constants, while the oxidation with IFC did not correlate well with any linear free energy relationships. 

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... 

The oxidation of monosubstituted aldonitrones to aldehyde and nitrosobenzene in MeCN/H20 mixture is first order in imidazolium dichromate (IDC) and nitrones, and a fractional order in acid. Added MnS04, 2,2 -bipyridyl (bpy), 1,10-phenanthroline and electron-withdrawing substituents decreased the rate which increased with the added oxalic acid and electron-releasing substituents. The rate data obeyed the Hammett relation. A mechanism involving the reaction of protonated nitrone with IDC in the rate-determining step is proposed." A similar oxidation in aqueous dimethyl-formamide (DMF) is of first-order dependence on IDC and aldonitrones, and H+ ions catalysed the rate. The rate decreased moderately with decrease in the dielectric constant. A mechanism of the reaction is proposed." ... 

The rate of oxidation of chalcones in ACOH-H2O has first order in imidazolium dichromate (INDC) and H+ ion and fractional order in the chalcones decreased with decreasing dielectric constant." The oxidation of phenoxyacetic acids in ACOH-H2O-HCIO4 is first order in nicotinium dichromate (NDC) and substrates, and second order in H+ ion. The electron-releasing substituents and increased percentage of AcOH increased the rate, which was decreased by electron-attracting substituents. The rate correlated with the Hammett relation, and Mn + ions exhibited noticeable catalytic effect." ... 

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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