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Chromium trioxide is generated by treating sodium dichromate with sulfuric acid: [6]. H 2 SO 4 + Na 2 Cr 2 O 7 → 2 CrO 3 + Na 2 SO 4 + H 2 O. Approximately 100,000 tonnes are produced annually by this or similar routes.
Chromic acid is capable of oxidizing many kinds of organic compounds and many variations on this reagent have been developed: Chromic acid in aqueous sulfuric acid and acetone is known as the Jones reagent, which will oxidize primary and secondary alcohols to carboxylic acids and ketones respectively, while rarely affecting unsaturated bonds. [12]
Jones reagent is a solution prepared by dissolving chromium trioxide in aqueous sulfuric acid. To effect a Jones oxidation, this acidic mixture is then added to an acetone solution of the substrate. Alternatively, potassium dichromate can be used in place of chromium trioxide.
The reagent is typically used in a sixfold excess. Methylene chloride is the typical solvent, with the solubility of 12.5 g/100 ml. The application of this reagent to oxidations was discovered by G. I. Poos, G. E. Arth, R. E. Beyler and L.H. Sarett in 1953. It was popularized by J. C. Collins several years later. [6]
Pyridinium chlorochromate in a vial. Pyridinium chlorochromate (PCC) is a yellow-orange salt with the formula [C 5 H 5 NH] + [CrO 3 Cl] −.It is a reagent in organic synthesis used primarily for oxidation of alcohols to form carbonyls.
The compound is prepared by the reaction of chromium(III) oxide with acetylacetone (Hacac): [3]. Cr 2 O 3 + 6 Hacac → 2 Cr(acac) 3 + 3 H 2 O. The complex has idealized D 3 symmetry.The Cr-O distances are 1.93 Å. [4]
Chromium(III) sulfate usually refers to the inorganic compounds with the formula Cr 2 (SO 4) 3. x(H 2 O), where x can range from 0 to 18. Additionally, ill-defined but commercially important "basic chromium sulfates" are known.
It is prepared by treating potassium dichromate with potassium hydroxide: . K 2 Cr 2 O 7 (aq) + 2 KOH → 2 K 2 CrO 4 + H 2 O. Or, the fusion of potassium hydroxide and chromium trioxide: