Imidazolium dichromate (IDC) and 1,1,3,3-tetramethylguanidinium dichromate (TMGDC)

Abstract

Imidazolum Dichromate (IDC) : IDC was conveniently prepared by addition of imidazole into the solution of chromic trioxide in a minimum of water and obtained in high yield as a bright orange-yellow solid. Allylic and benzylic alcohols were rapidly oxidized to the corresponding carbonyl compounds, while saturated aliphatic alcohols were slowly oxidized. IDC is a mild selective reagent for the oxidation of allylic and benzylic alcohols in the presence of saturated aliphatic alcohols. 1,1,3,3-Tetramethylguanidinium Dichromate (TMGDC) : TMGDC was easily prepared in high yield by the slow addition of 1,1,3,3-tetramethylguanidine into aqueous chromim trioxide solution and obtained as a light sensitive bright organge-yellow solid The use of TMGDC and pyridinium p-toluenesulfonate in an equal molar ratio was effective for the oxidation of benzylic, allylic, and saturated aliphatic alcohols to the corresponding carbonyl compounds, while TMGDC alone did not oxidize alcohols.