Jones oxidation
The Jones oxidation is an organic reaction for the oxidation of primary and secondary alcohols to carboxylic acids and ketones, respectively. It is named after its discoverer, Sir Ewart Jones.

Jones reagent consists of chromium trioxide and sulfuric acid dissolved in a mixture of acetone and water. As an alternative, potassium dichromate can be used in place of chromium trioxide. The oxidation is very rapid, quite exothermic, and the yields are typically high. The reagent rarely oxidizes unsaturated bonds.

Although useful reagent for some applications, due to the carcinogenic nature of chromium(VI), the Jones oxidation has slowly been replaced by other oxidation methods.

Stoichiometry and mechanism
Jones reagent will convert primary and secondary alcohols to aldehydes and ketones, respectively. Depending on the reaction conditions, the aldehydes may then be converted to carboxylic acids. For oxidations to the aldehydes and ketones, two equivalents of chromic acid oxidize three equivalents of the alcohol:
 2 HCrO4−  +  3 RR'C(OH)H  +  8 H+  +  4 H2O   →   2 [Cr(H2O)6]3+  +  3 RR'CO

For oxidation of primary alcohols to carboxylic acids, 4 equivalents of chromic acid oxidize 3 equivalents of the alcohol. The aldehyde is an intermediate.
4 HCrO4− + 3 RCH2OH + 16 H+ + 11 H2O → 4 [Cr(H2O)6]3+ + 3 RCOOH
The inorganic products are green, characteristic of chromium(III) aquo complexes.

Like many other oxidations of alcohols by metal oxides, the reaction proceeds via the formation of a mixed chromate ester: These esters have the formula CrO3(OCH2R)−
CrO3(OH)− + RCH2OH → CrO3(OCH2R)− + H2O
Like conventional esters, the formation of this chromate ester is accelerated by the acid.  These esters can be isolated when the alcohol is tertiary because these lack the α hydrogen that would be lost to form the carbonyl.  For example, using tert-butyl alcohol, one can isolate tert-butyl chromate ((CH3)3CO)2CrO2), which is itself a good oxidant.

For those structures with hydrogen alpha to the oxygen, the chromate esters degrade, releasing the carbonyl product and an ill-defined Cr(IV) product:
CrO3(OCH2R)− → "CrO2OH−" + O=CHR
The deuterated alcohols HOCD2R oxidize about six times slower than the undeuterated derivatives.  This large kinetic isotope effect shows that the C–H (or C–D) bond breaks in the rate-determining step. 

The reaction stoichiometry implicates the Cr(IV) species "CrO2OH−", which comproportionates with the chromic acid to give a Cr(V) oxide, which also functions as an oxidant for the alcohol.

The oxidation of the aldehydes is proposed to proceed via the formation of hemiacetal-like intermediates, which arise from the addition of the O3CrO-H− bond across the C=O bond.

Illustrative reactions and applications
It remains useful in organic synthesis. A variety of spectroscopic techniques, including Infrared spectroscopy, can be used to monitor the progress of a Jones oxidation reaction.  At one time the Jones oxidation was used in breathalyzers.
Org. Synth. , 45, 28
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Related processes
Several other chromium compounds are used for the oxidation of alcohols. These include Collins reagent and pyridinium chlorochromate.

The Sarett oxidation is a similar process.