Jones oxidation: Difference between revisions - Wikipedia

Line 1:

{{Short description|Oxidation of alcohol}}

{{Reactionbox

| Name = Jones oxidation

| Type = Organic redox reaction

| NamedAfter = [[Ewart Jones]]

| Section3 = {{Reactionbox Identifiers

| OrganicChemistryNamed = jones-oxidation

| RSC_ontology_id = 0000356

}}▼

}}

▲ }}

The '''Jones oxidation''' is an [[organic reaction]] for the [[redox|oxidation]] of primary and secondary [[alcohol]]s to [[carboxylic acid]]s and [[ketone]]s, respectively. It is named after its discoverer, [[Ewart Jones|Sir Ewart Jones]].<ref name="Bowden 1946">{{cite journal|author1=Bowden, K. |author2=Heilbron, I. M. |author3=Jones, E. R. H |journal = [[J. Chem. Soc.]]|year = 1946|pages = 39|doi = 10.1039/jr9460000039|title = 13. Researches on acetylenic compounds. Part I. The preparation of acetylenic ketones by oxidation of acetylenic carbinols and glycols}}</ref>▼

The '''Jones oxidation''' is an [[organic reaction]] for the [[redox|oxidation]] of primary and secondary [[alcohol (chemistry)|alcohol]]s to [[carboxylic acid]]s and [[ketone]]s, respectively. It is named after its discoverer, [[Ewart Jones|Sir Ewart Jones]]. The reaction was an early method for the oxidation of alcohols. Its use has subsided because milder, more selective reagents have been developed, e.g. [[Collins reagent]].<ref>{{cite book |doi=10.1007/0-387-25725-X_1|chapter=Chromium-based Reagents|title=Oxidation of Alcohols to Aldehydes and Ketones|series=Basic Reactions in Organic Synthesis|year=2006|pages=1–95|isbn=0-387-23607-4}}</ref>

[[File:Jones Oxidation Scheme.png|center|300px|The Jones oxidation]]

'''Jones reagent''' consistsis ofa solution prepared by dissolving [[chromium trioxide]] andin aqueous [[sulfuric acid]]. dissolved inTo effect a Jones oxidation, this acidic mixture ofis then added to an [[acetone]] andsolution [[water]].of Asthe ansubstrate. alternativeAlternatively, [[potassium dichromate]] can be used in place of chromium trioxide. The oxidation is very rapid, and quite [[exothermic]],. and the yieldsYields are typically high. The reagent rarelyis oxidizesconvenient and cheap. However, Cr(VI) compounds are carcinogenic, which deters the use of unsaturatedthis bondsmethodology.

==Stoichiometry and mechanism==▼

▲==Stoichiometry==

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.

Line 21:

The inorganic products are green, characteristic of [[metal aquo complex|chromium(III) aquo complexes]].<ref name=cyclooct/>

==Mechanism==

Like many other oxidations of alcohols by metal oxides, the reaction proceeds via the formation of a mixed [[chromate ester]]:<ref name=March>{{March6th}}</ref><ref>{{cite book|author1=Ley, S. V. |author2=Madin, A. |title = Comprehensive organic synthesis|year = 1991|volume=7|pages = 253–256 |editor1=B. M. Trost |editor2=I. Fleming |publisher=Pergamon Press|place=Oxford}}</ref> These [[ester]]s 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 [[alpha and beta carbon|α]] hydrogen that would be lost to form the carbonyl. For example, using [[tert-Butyl alcohol|''tert''-butyl alcohol]], one can isolate [[Tert-Butyl chromate|''tert''-butyl chromate]] ((CH₃)₃CO)₂CrO₂), which is itself a good oxidant.<ref>Fillmore Freeman, "Di-tert-butyl Chromate" Encyclopedia of Reagents for Organic Synthesis, 2001, John Wiley & Sons, Ltd. {{DOIdoi|10.1002/047084289X.rd059m}}</ref>

For those structures where there is awith hydrogen atom on the carbon adjacentalpha to the oxygen, the chromate esters degrade, releasing the carbonyl product and an ill-defined Cr(IV) product:

:CrO₃(OCH₂R)⁻ → "CrO₂OH⁻" + O=CHR

The partially 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 [[comproportionation|comproportionates]] with the chromic acid to give a Cr(V) oxide, which also functions as an oxidant for the alcohol.<ref>Oxidation in Organic Chemistry. Edited by K. B. Wiberg, Academic Press, NY, 1965.</ref>

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.

The reagent rarely oxidizes unsaturated bonds. In certain cases, depending on very

exact stereoelectronic factors, production of epoxides may occur.

==Illustrative reactions and applications==

It remains useful in [[organic synthesis]].<ref name=cyclooct>{{OrgSynth|collvol volume= 545|collvolpagespages = 31028|year = 19731965|title = Cyclooctanone|author first1= E. J.|last1= Eisenbraun|prep doi= cv5p031010.15227/orgsyn.045.0028}}</ref><ref>{{OrgSynth|collvol volume= 545|collvolpages page= 86677|year = 19731965|title = Nortricyclanone|author first1=J. |last1=Meinwald, |first2=J. |last2=Crandall, and |first3=W. E. |last3=Hymans|prep doi= cv5p086610.15227/orgsyn.045.0077}}</ref> 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 [[breathalyzer]]s.

==Related processes==

{{main|Oxidation with chromium(VI) complexes}}

Several other chromium compounds are used for the oxidation of alcohols.<ref name=March/> These include [[Collins reagent]] and [[pyridinium chlorochromate]].

The principal reagents are Collins reagent, PDC, and PCC. These reagents represent improvements over inorganic chromium(VI) reagents such as Jones reagent.

==Historical references==▼

The [[Sarett oxidation]] is a similar process.

▲The '''Jones oxidation''' is an [[organic reaction]] for the [[redox|oxidation]] of primary and secondary [[alcohol]]s to [[carboxylic acid]]s and [[ketone]]s, respectively. It is named after its discoverer, [[Ewart Jones|Sir Ewart Jones]].<ref name="Bowden 1946">*{{cite journal|author1=Bowden, K. |author2=Heilbron, I. M. |author3=Jones, E. R. H |journal = [[J. Chem. Soc.]]|year = 1946|pages = 39|doi = 10.1039/jr9460000039|title = 13. Researches on acetylenic compounds. Part I. The preparation of acetylenic ketones by oxidation of acetylenic carbinols and glycols}}</ref>

*{{cite journal|author1=Heilbron, I.M. |author2=Jones, E.R.H. |author3=Sondheimer, F |journal = [[J. Chem. Soc.]]|year = 1949|pages = 604|doi = 10.1039/jr9490000604|title = 129. Researches on acetylenic compounds. Part XV. The oxidation of primary acetylenic carbinols and glycols}}▼

*{{cite journal|author = Bladon, P|journal = [[J. Chem. Soc.]]|year = 1951|pages = 2402|doi = 10.1039/jr9510002402|title = 532. Studies in the sterol group. Part LII. Infra-red absorption of nuclear tri- and tetra-substituted ethylenic centres|last2 = Fabian|first2 = Joyce M.|last3 = Henbest|first3 = H. B.|last4 = Koch|first4 = H. P.|last5 = Wood|first5 = Geoffrey W.}}▼

*{{cite journal|author = Jones, E. R. H|journal = [[J. Chem. Soc.]]|year = 1953|pages = 457|doi = 10.1039/jr9530000457|title = 92. The chemistry of the triterpenes. Part XIII. The further characterisation of polyporenic acid A}}▼

*{{cite journal|author = Jones, E. R. H|journal = [[J. Chem. Soc.]]|year = 1953|pages = 2548|doi = 10.1039/jr9530002548|title = 520. The chemistry of the triterpenes and related compounds. Part XVIII. Elucidation of the structure of polyporenic acid C}}▼

*{{cite journal|author = Jones, E. R. H|journal = [[J. Chem. Soc.]]|year = 1953|pages = 3019|doi = 10.1039/jr9530003019|title = 599. The chemistry of the triterpenes and related compounds. Part XIX. Further evidence concerning the structure of polyporenic acid A}}▼

*{{cite journal|author = [[C. Djerassi]], R. Engle and A. Bowers|title = Notes – The Direct Conversion of Steroidal Δ5-3β-Alcohols to Δ5- and Δ4-3-Ketones|year = 1956|journal = [[J. Org. Chem.]]|volume = 21|issue = 12|pages = 1547–1549|doi = 10.1021/jo01118a627}}▼

==References==

{{reflist}}

▲==Historical references==

▲*{{cite journal|author1=Heilbron, I.M. |author2=Jones, E.R.H. |author3=Sondheimer, F |journal = [[J. Chem. Soc.]]|year = 1949|pages = 604|doi = 10.1039/jr9490000604|title = 129. Researches on acetylenic compounds. Part XV. The oxidation of primary acetylenic carbinols and glycols}}

▲*{{cite journal|author = Bladon, P|journal = [[J. Chem. Soc.]]|year = 1951|pages = 2402|doi = 10.1039/jr9510002402|title = 532. Studies in the sterol group. Part LII. Infra-red absorption of nuclear tri- and tetra-substituted ethylenic centres|last2 = Fabian|first2 = Joyce M.|last3 = Henbest|first3 = H. B.|last4 = Koch|first4 = H. P.|last5 = Wood|first5 = Geoffrey W.}}

▲*{{cite journal|author = Jones, E. R. H|journal = [[J. Chem. Soc.]]|year = 1953|pages = 457|doi = 10.1039/jr9530000457|title = 92. The chemistry of the triterpenes. Part XIII. The further characterisation of polyporenic acid A}}

▲*{{cite journal|author = Jones, E. R. H|journal = [[J. Chem. Soc.]]|year = 1953|pages = 2548|doi = 10.1039/jr9530002548|title = 520. The chemistry of the triterpenes and related compounds. Part XVIII. Elucidation of the structure of polyporenic acid C}}

▲*{{cite journal|author = Jones, E. R. H|journal = [[J. Chem. Soc.]]|year = 1953|pages = 3019|doi = 10.1039/jr9530003019|title = 599. The chemistry of the triterpenes and related compounds. Part XIX. Further evidence concerning the structure of polyporenic acid A}}

▲*{{cite journal|author = [[C. Djerassi]], R. Engle and A. Bowers|title = Notes – The Direct Conversion of Steroidal Δ5-3β-Alcohols to Δ5- and Δ4-3-Ketones|year = 1956|journal = [[J. Org. Chem.]]|volume = 21|issue = 12|pages = 1547–1549|doi = 10.1021/jo01118a627}}

[[Category:Organic oxidation reactions]]