Quinolinium dichromate, oxidation with

A DIE of k 2o/k )2o = 3.2 has been found in the hydrolysis of a-benzoyloxystyrenes, 382, in concentrated perchloric acid solution450. The rate of hydrolysis was found to be linear with the acidity function, Ho- A small inverse deuterium KIE, A h /I d = 0.78, at the -carbon has been found in the oxidation of cinnamic and crotonic acids451 by quinolinium dichromate. The reaction involves electrophilic attack on the double bond and a carbonium-ion intermediate (p = —4.0). A small inverse D KIE (k /k ->) = 0.80, p = —4.0] has been also observed452 in the acid cleavage of substituted styrenes by quinolinium dichromate in DMF in the presence of acid452. 

Oxidation of aliphatic aldehydes by quinolinium dichromate in aqueous acetic acid shows first-order kinetics in substrate and oxidant, and second-order with respect to H+.319 Hydrated aldehyde and protonated oxidant are suggested to be the reactive species, with Zucker-Hammett plots supporting proton abstraction by water in the slow step. 

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... 

Substituted benzaldehydes are oxidized by quinolinium dichromate in DMF containing HCl, with electron-releasing substituents accelerating the reaction p = —0.90). The first step, hydrogen abstraction, is rate-determining the deuterium solvent isotope effect is 5.14 at 333 K. 

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