Pyridinium chlorochromate

Chemical properties

Pyridinium chlorochromate is orange crystalline powder

The Uses of Pyridinium chlorochromate

Pyridinium chlorochromate is usually used to oxidize an allylic methylene group.
Oxidation of primary alcohols to aldehydes

Pyridinium dichromate (PDC) or pyridinium chlorochromate (PCC) in anhydrous media such as dichloromethane oxidizes primary alcohols to aldehydes while avoiding overoxidation to carboxylic acids.

The Uses of Pyridinium chlorochromate

To a solution of the SM (1.055 g, 3.23 mmol) in DCM was added PCC (0.915 g, 4.20 mmol) and celite (1.96 g). The reaction mixture was stirred at RT for 1 h 50 min, then a second portion of PCC (0.494 g, 2.30 mmol) was added. Stirring was continued for another 1 h, after which time the solids were removed via filtration through celite. The filtrate was concentrated in vacuo and the residue purified by flash chromatography (10-50% EtOAc/hexane) to provide the product as a white solid. [0.647 g, 62%] [UK Pat App GB2463151A, page 133]

The Uses of Pyridinium chlorochromate

Oxidizing agent in organic synthesis.
PCC is pyridinium chlorochromate; PDC is pyridinium dichromate. Both are used in dichloromethane.

The Uses of Pyridinium chlorochromate

Pyridinium chlorochromate is used as an oxidizing agent to convert primary and secondary alcohols to aldehydes and ketones respectively. It is involved in the preparation of cyclohexanone, (-)-pulegone and lactones. It plays an important role in the selective mono-oxidation of xylenes to tolualdehydes and arylhydroxyamines to nitroso compounds. Furthermore, it is utilized as an oxidant for amino acids, L-cystine, aniline, cycloalkanols, vicinal and non-vicinal diols as well as in the Babler oxidation reaction.

What are the applications of Application

Pyridinium chlorochromate is Used to oxidize an allylic methylene group

Reactions

Pyridinium chlorochromate (PCC) is a widespread used oxidation reagent but lacks of selectivity with unsaturated compounds. Furthermore, the workup procedure is quite tedious. Absorption of PCC onto silica gel improves the oxidation but then a reagent excess is necessary to reach appropriate rates. These drawbacks can be overcome by sonication leading to short reaction times and only an small excess of 1.2.-1.5 eq. of PCC is required. Using this reagent has been used to oxidise borneol to camphor in 85% yield.

Purification Methods

Dry it in a vacuum for 1hour. It is not hygroscopic and can be stored for extended periods at room temperature without change. If the purity is very suspect, it can be readily prepared. [Corey & Scuggs Tetrahedron Lett 2647 1975, Piancatelli et al. Synthesis 245 1982.] (Possible CARCINOGEN.) § Available commercially on a polymer support.