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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] This compound is a dark-purple solid under anhydrous conditions and bright orange when wet. The substance dissolves in water ...
Download as PDF; Printable version; In other projects ... CrO 2, which includes the hypothetical compound chromium(II) chromate; Chromium trioxide (chromium(VI) oxide ...
Download as PDF; Printable version; In other projects Wikimedia Commons; ... Chromium trioxide (Chromic acid) – CrO 3; Chromium(II) chloride (chromous chloride ...
Chromium(III) oxide is amphoteric. Although insoluble in water, it reacts with acid to produce salts of hydrated chromium ions such as [Cr(H 2 O) 6] 3+. [10] It is also attacked by concentrated alkali to yield salts of [Cr(OH) 6] 3−. When heated with finely divided carbon or aluminium, it is reduced to chromium metal: Cr 2 O 3 + 2 Al → 2 Cr ...
Under these conditions deep red crystals of chromium trioxide precipitate from the mixture, without further colour change. Chromium trioxide is the anhydride of molecular chromic acid. It is a Lewis acid and can react with a Lewis base, such as pyridine in a non-aqueous medium such as dichloromethane ( Collins reagent ).
Collins reagent is the complex of chromium(VI) oxide with pyridine in dichloromethane. [2] This metal-pyridine complex, a red solid, is used to oxidize primary alcohols to the corresponding aldehydes and secondary alcohols to the corresponding ketones. This complex is a hygroscopic orange solid. [1]
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 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 pyridine in methylene chloride. [4] A second family of Cr(VI) reagents are salts, featuring the pyridinium cation (C 5 H 5 NH +).