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Chromium trioxide (also known as chromium(VI) oxide or chromic anhydride) is an inorganic compound with the formula CrO 3.It is the acidic anhydride of chromic acid, and is sometimes marketed under the same name. [6]
CAS Number. 1308-38-9 ... Chromates can be formed by the oxidation of chromium(III) oxide and another oxide in a basic environment: 2 Cr 2 O 3 + 4 MO + 3 O 2 → 4 ...
It was popularized for selective oxidation of primary and secondary alcohols to carbonyl compounds. Collins reagent is a solution of the same CrO 3 (pyridine) 2 but in dichloromethane. The Ratcliffe variant of Collins reagent relates to details of the preparation of this solution, i.e., the addition of chromium trioxide to a solution of ...
Oxidation with chromium(VI)-amine complexes Collins reagent can be used as an alternative to the Jones reagent and pyridinium chlorochromate (PCC) when oxidizing secondary alcohols to ketones . PCC and pyridinium dichromate (PDC) oxidations have largely supplanted Collins oxidation.
Compounds of chromium(V) are rather rare; the oxidation state +5 is only realized in few compounds but are intermediates in many reactions involving oxidations by chromate. The only binary compound is the volatile chromium(V) fluoride (CrF 5). This red solid has a melting point of 30 °C and a boiling point of 117 °C.
The collins oxidation first came about in 1968 when J.C. Collins used pre-formed CrO3•2Pyr dissolved in dichloromethane to oxidize alcohols. [5] Although difficult, it was beneficial at the time because it provided an alternative to the Sarett oxidation, that used pyridine as a solvent. [5]
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The Jones oxidation. 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 oxidation is very rapid and quite ...