[109201-26-5] · C6H10Cr2N4O7 · Imidazolium Dichromate · (MW 354.20)
(mild selective reagent for the oxidation of allylic and benzylic alcohols to the corresponding carbonyl compounds)
Alternate Name: IDC.
Physical Data: mp 130-131 °C; nonhygroscopic; air stable yellow crystals.
Solubility: readily sol DMF, DMSO; very slightly sol acetone, dichloromethane, trichloromethane.
Preparative Method: easily prepared by the addition of Imidazole to a solution of an equimolar amount of Chromium(VI) Oxide in a minimum amount of water.1 The yellow crystals are collected, washed with acetone, and dried in vacuo at rt.
Handling, Storage, and Precautions: all chromium(VI) reagents must be handled with care. The mutagenicity of chromium(VI) compounds is well documented.2 This reagent should be handled in a fume hood.
Imidazolium dichromate oxidizes cinnamyl alcohol and benzhydrol to cinnamaldehyde (91%) and benzophenone (93%), respectively, at rt.1 Allylic alcohols are oxidized faster than benzylic alcohols and saturated aliphatic alcohols react slowest. Geraniol is oxidized to geranial (82% yield) with 6% (E) to (Z) isomerization at the double bond. 4-(3-Hydroxypropyl)benzyl alcohol is selectively oxidized to 4-(3-hydroxypropyl)benzaldehyde (eq 1). The selectivity achieved with IDC is comparable to that of 4-(Dimethylamino)pyridinium Chlorochromate (DMAP.HCrO3Cl).3,4
University of California, Irvine, CA, USA