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Alcohol oxidation

January 01, 1970

Alcohol oxidation is a collection of oxidation reactions in organic chemistry that convert alcohols to aldehydes, ketones, carboxylic acids, and esters where the carbon carries a higher oxidation state. The reaction mainly applies to primary and secondary alcohols. Secondary alcohols form ketones, while primary alcohols form aldehydes or carboxylic acids.[1]

The reaction can occur using a variety of oxidants.

Stages in the oxidation of primary alcohols to carboxylic acids via aldehydes and aldehyde hydrates

In principle, a simple way to oxidize an alcohols uses an oxygen atom and produce water: In practice, oxygen atoms are unavailable, so the above equation is only conceptual. Instead, most oxidations use oxides-based reagents, such as metal oxo complexes, sulfoxides, and iodine oxides.

Through a variety of mechanisms, the removal of a hydride equivalent converts a primary or secondary alcohol to an aldehyde or ketone, respectively. The oxidation of primary alcohols to carboxylic acids normally proceeds via the corresponding aldehyde, which is transformed via an aldehyde hydrate (gem-diol, R-CH(OH)2) by reaction with water. Thus, the oxidation of a primary alcohol at the aldehyde level without further oxidation to the carboxylic acid is possible by performing the reaction in absence of water, so that no aldehyde hydrate can be formed.

Ketone and aldehyde formation edit

 
Oxidation of alcohols to aldehydes and ketones

Many reagents oxidize secondary alcohols to ketones and primary alcohols to aldehydes. Allylic and benzylic alcohols represent special cases. Aldehydes are susceptible to over oxidation to carboxylic acids.

Chromium(VI) reagents edit

 

Chromium(VI) reagents are commonly used for these oxidations. One family of Cr(VI) reagents employs the complex CrO3(pyridine)2.[2]

  • Sarett's reagent: a solution of CrO3(pyridine)2 in pyridine. It was popularized for selective oxidation of primary and secondary alcohols to carbonyl compounds.
  • Collins reagent is a solution of the same CrO3(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 pyridine in methylene chloride.[3]

A second family of Cr(VI) reagents are salts, featuring the pyridinium cation (C5H5NH+).

These salts are less reactive, more easily handled, and more selective than Collins reagent in oxidations of alcohols.

The above reagents represent improvements over the older Jones reagent, a solution of chromium trioxide in aqueous sulfuric acid.

Dess–Martin and related oxidations edit

The Dess–Martin periodinane is a mild oxidant for the conversion of alcohols to aldehydes or ketones.[4] The reaction is performed under standard conditions, at room temperature, most often in dichloromethane. The reaction takes between half an hour and two hours to complete. The product is then separated from the spent periodinane.[5] Many iodosyl-based oxidants have been developed, e.g. IBX.

Swern oxidation edit

Swern oxidation uses oxalyl chloride, dimethylsulfoxide, and an organic base, such as triethylamine.

 

The by-products are dimethyl sulfide (Me2S), carbon monoxide (CO), carbon dioxide (CO2) and – when triethylamine is used as base – triethylammonium chloride (C6H15NHCl).

Oppenauer oxidation edit

Main article: Oppenauer oxidation
 

This seldom-used method interconverts alcohols and carbonyls.

Niche methods edit

Ley oxidation uses NMO as the stoichiometric oxidant with tetrapropylammonium perruthenate as a catalyst.

Fétizon oxidation, also a seldom-used method, uses silver carbonate supported on Celite. This reagent operates through single electron oxidation by the silver cations.

 

Another method is the oxoammonium-catalyzed oxidation.

Additionally, sodium hypochlorite (or household bleach) in acetone has been reported for efficient conversion of secondary alcohols in the presence of primary alcohols (Stevens oxidation).[6]

soluble transition metal complexes catalyze the oxidation of alcohols by presence of dioxygen or another terminal oxidant.[7]

Oxidation of diols edit

 
Oxidative cleavage of carbon-carbon bond in 1,2-diols

Compounds possessing two hydroxy groups located on adjacent carbons —that is, vicinal diols/ 1,2-diols — suffer oxidative breakage at a carbon-carbon bond with some oxidants such as sodium periodate (NaIO4), (diacetoxyiodo)benzene (PhI(OAc)2)[8] or lead tetraacetate (Pb(OAc)4), resulting in generation of two carbonyl groups. The reaction is also known as glycol cleavage.

Oxidation of primary alcohols to carboxylic acids edit

 

When a primary alcohol is converted to a carboxylic acid, the terminal carbon atom increases its oxidation state by four. The direct oxidation of primary alcohols to carboxylic acids can be carried out using a variety of reagents.

Aldehydes are readily oxidized using Cr(VI) and Mn(VII) reagents to carboxylic acids.

Potassium permanganate edit

Potassium permanganate (KMnO4) oxidizes primary alcohols to carboxylic acids very efficiently. This reaction, which was first described in detail by Fournier,[9][10] is typically carried out by adding KMnO4 to a solution or suspension of the alcohol in an alkaline aqueous solution. For the reaction to proceed efficiently, the alcohol must be at least partially dissolved in the aqueous solution. This can be facilitated by the addition of an organic co-solvent such as dioxane, pyridine, acetone or t-BuOH. KMnO4 reacts with many functional groups, such as secondary alcohols, 1,2-diols, aldehydes, alkenes, oximes, sulfides and thiols, and carbon-carbon double bonds. Thus, selectivity is an issue.

 
Ciufolini and Swaminathan [11] oxidized a primary alcohol to carboxylic acid with KMnO4 in aqueous NaOH during the obtention of a rare amino acid derivative needed for the preparation of antibiotics isolated from Actinomadura luzonensis, a microorganism found in a soil sample collected in Luzon island in the Philippines

Jones oxidation edit

Main article: Jones oxidation

The so-called Jones reagent, prepared from chromium trioxide (CrO3) and aqueous sulfuric acid, oxidizes alcohols to a carboxylic acid. The protocol frequently affords substantial amounts of esters.[12] Problems are the toxicity and environmental unfriendliness of the reagent. Catalytic variant, involving treatment with excess of periodic acid (H5IO6) have been described.[13]

 
Crimmins and DeBaillie[14]

Two-step oxidation of alcohols to acids via isolated aldehydes edit

As a lot of the aforementioned conditions for the oxidations of primary alcohols to acids are harsh and not compatible with common protection groups, organic chemists often use a two-step procedure for the oxidation to acids. The alcohol is oxidized to an aldehyde using one of the many procedures above. This sequence is often used in natural product synthesis as in their synthesis of platencin.[15]

Niche methods and reagents edit

Ruthenium tetroxide is an aggressive, seldom-used agent that allows mild reaction conditions.

Heyns oxidation.[16]

The use of chlorites as terminal oxidants in conjunction with both hypochlorites and TEMPO gives carboxylic acids without chlorination side products.[17] The reaction is usually carried out in two steps in the same pot: partial oxidation is effected with TEMPO and hypochlorite, then chlorite is added to complete the oxidation. Only primary alcohol oxidation is observed. In conjunction with Sharpless dihydroxylation, this method can be used to generate enantiopure α-hydroxy acids.[18]

The Pinnick oxidation uses sodium chlorite.[19]

References edit

  1. ^ Burton, George et al. (2000). Salters Advanced Chemistry: Chemical (2nd ed.). Heinemann. ISBN 0-435-63120-9
  2. ^ "Chromium-based Reagents". Oxidation of Alcohols to Aldehydes and Ketones. Basic Reactions in Organic Synthesis. 2006. pp. 1–95. doi:10.1007/0-387-25725-X_1. ISBN 0-387-23607-4.
  3. ^ J. C. Collins, W.W. Hess (1972). "Aldehydes from Primary Alcohols by Oxidation with Chromium Trioxide: Heptanal". Organic Syntheses. 52: 5. doi:10.15227/orgsyn.052.0005.
  4. ^ Dess, D. B.; Martin, J. C. J. Am. Chem. Soc. 1991, 113, 7277–87.
  5. ^ J. S. Yadav, et al. "Recyclable 2nd generation ionic liquids as green solvents for the oxidation of alcohols with hypervalent iodine reagents", Tetrahedron, 2004, 60, 2131–35
  6. ^ Stevens R, Chapman KT, Weller HN (1980). "Convenient and inexpensive procedure for oxidation of secondary alcohols to ketones". Journal of Organic Chemistry. 45 (10): 2030–2032. doi:10.1021/jo01298a066.
  7. ^ Parmeggiani, Camilla; Cardona, Francesca (2012-01-03). "Transition metal based catalysts in the aerobic oxidation of alcohols". Green Chemistry. 14 (3): 547–564. doi:10.1039/C2GC16344F. ISSN 1463-9270.
  8. ^ Nicolaou KC, Adsool VA, Hale CR (April 2010). "An expedient procedure for the oxidative cleavage of olefinic bonds with PhI(OAc)2, NMO, and catalytic OsO4". Organic Letters. 12 (7): 1552–5. doi:10.1021/ol100290a. PMC 2848477. PMID 20192259.
  9. ^ Fournier, H.M. (1907). "Transformation des alcools primaires saturès en acides monobasiques correspondants". C. R. Acad. Sci.: 331.
  10. ^ Fournier, H.M. (20 July 1909). "Sur la préparation des acides gras et de leurs anhydres". Bull. Soc. Chim. Fr.: 920.
  11. ^ Ciufolini, M.A.; Swaminathan, S. (1989). "Synthesis of a model depsipeptide segment of Luzopeptins (BBM 928), potent antitumor and antiretroviral antibiotics". Tetrahedron Lett. 30 (23): 3027. doi:10.1016/S0040-4039(00)99393-6.
  12. ^ "Chromium-based Reagents". Oxidation of Alcohols to Aldehydes and Ketones. Basic Reactions in Organic Synthesis. 2006. pp. 1–95. doi:10.1007/0-387-25725-X_1. ISBN 0-387-23607-4.
  13. ^ Song, Z.J.; Zhao, M.; Desmond, R.; Devine, P.; Tschaen, D.M.; Tillyer, R.; Frey, L.; Heid, R.; Xu, F.; Foster, B.; Li, J.; Reamer, R.; Volante, R.; Grabowski, E.J.J.; Dolling, U.H.; Reider, P.J. (1999). "Practical Asymmetric Synthesis of an Endothelin Receptor Antagonist". J. Org. Chem. 64 (26): 9658. doi:10.1021/jo991292t.
  14. ^ Crimmins, M.T. & DeBaillie, A.C. (2006). "Enantioselective Total Synthesis of Bistramide A". J. Am. Chem. Soc. 128 (15): 4936–7. doi:10.1021/ja057686l. PMC 2546575. PMID 16608311.
  15. ^ Nicolaou K.C.; Scott Tria G.; Edmonds D. J. (2008). "Total Synthesis of Platencin". Angew. Chem. 120 (9): 1804. doi:10.1002/ange.200800066.
  16. ^ Marcos Fernández; Gabriel Tojo (2006). Oxidation of Primary Alcohols to Carboxylic Acids: A Guide to Current Common Practice (Basic Reactions in Organic Synthesis). Berlin: Springer. ISBN 0-387-35431-X.
  17. ^ Song, Z. J.; Zhao, M.; Desmond, R.; Devine, P.; Tschaen, D. M.; Tillyer, R.; Frey, L.; Heid, R.; Xu, F.; Foster, B.; Li, J.; Reamer, R.; Volante, R.; Grabowski, E. J. J.; Dolling, U. H.; Reider, P. J.; Okada, S.; Kato, Y.; Mano, E. J. Org. Chem. 1999, 64, 9658.
  18. ^ Sharpless, K. B.; Amberg, W.; Bennani, Y. L.; Crispino, G. A.; Hartung, J.; Jeong, K. S.; Kwong, H. L.; Morikawa, K.; Wang, Z. M.; Xu, D.; Zhang, X. L. J. Org. Chem. 1992, 57, 2768.
  19. ^ Bal B.S.; Childers, Jr. W.E.; Pinnick H.W. (1981). "Oxidation of α,β-unsaturated aldehydes". Tetrahedron (abstract). 37 (11): 2091. doi:10.1016/S0040-4020(01)97963-3.

January 01, 1970
alcohol, oxidation, collection, oxidation, reactions, organic, chemistry, that, convert, alcohols, aldehydes, ketones, carboxylic, acids, esters, where, carbon, carries, higher, oxidation, state, reaction, mainly, applies, primary, secondary, alcohols, seconda. Alcohol oxidation is a collection of oxidation reactions in organic chemistry that convert alcohols to aldehydes ketones carboxylic acids and esters where the carbon carries a higher oxidation state The reaction mainly applies to primary and secondary alcohols Secondary alcohols form ketones while primary alcohols form aldehydes or carboxylic acids 1 The reaction can occur using a variety of oxidants Stages in the oxidation of primary alcohols to carboxylic acids via aldehydes and aldehyde hydrates In principle a simple way to oxidize an alcohols uses an oxygen atom and produce water In practice oxygen atoms are unavailable so the above equation is only conceptual Instead most oxidations use oxides based reagents such as metal oxo complexes sulfoxides and iodine oxides Through a variety of mechanisms the removal of a hydride equivalent converts a primary or secondary alcohol to an aldehyde or ketone respectively The oxidation of primary alcohols to carboxylic acids normally proceeds via the corresponding aldehyde which is transformed via an aldehyde hydrate gem diol R CH OH 2 by reaction with water Thus the oxidation of a primary alcohol at the aldehyde level without further oxidation to the carboxylic acid is possible by performing the reaction in absence of water so that no aldehyde hydrate can be formed Contents 1 Ketone and aldehyde formation 1 1 Chromium VI reagents 1 2 Dess Martin and related oxidations 1 3 Swern oxidation 1 4 Oppenauer oxidation 1 5 Niche methods 2 Oxidation of diols 3 Oxidation of primary alcohols to carboxylic acids 3 1 Potassium permanganate 3 2 Jones oxidation 3 3 Two step oxidation of alcohols to acids via isolated aldehydes 3 4 Niche methods and reagents 4 ReferencesKetone and aldehyde formation edit nbsp Oxidation of alcohols to aldehydes and ketones Many reagents oxidize secondary alcohols to ketones and primary alcohols to aldehydes Allylic and benzylic alcohols represent special cases Aldehydes are susceptible to over oxidation to carboxylic acids Chromium VI reagents edit nbsp Chromium VI reagents are commonly used for these oxidations One family of Cr VI reagents employs the complex CrO3 pyridine 2 2 Sarett s reagent a solution of CrO3 pyridine 2 in pyridine It was popularized for selective oxidation of primary and secondary alcohols to carbonyl compounds Collins reagent is a solution of the same CrO3 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 pyridine in methylene chloride 3 A second family of Cr VI reagents are salts featuring the pyridinium cation C5H5NH pyridinium dichromate PDC is the pyridium salt of dichromate Cr2O7 2 pyridinium chlorochromate PCC is the pyridinium salt of CrO3Cl These salts are less reactive more easily handled and more selective than Collins reagent in oxidations of alcohols The above reagents represent improvements over the older Jones reagent a solution of chromium trioxide in aqueous sulfuric acid Dess Martin and related oxidations edit The Dess Martin periodinane is a mild oxidant for the conversion of alcohols to aldehydes or ketones 4 The reaction is performed under standard conditions at room temperature most often in dichloromethane The reaction takes between half an hour and two hours to complete The product is then separated from the spent periodinane 5 Many iodosyl based oxidants have been developed e g IBX Swern oxidation edit Swern oxidation uses oxalyl chloride dimethylsulfoxide and an organic base such as triethylamine nbsp The by products are dimethyl sulfide Me2S carbon monoxide CO carbon dioxide CO2 and when triethylamine is used as base triethylammonium chloride C6H15NHCl Oppenauer oxidation edit Main article Oppenauer oxidation nbsp This seldom used method interconverts alcohols and carbonyls Niche methods edit Ley oxidation uses NMO as the stoichiometric oxidant with tetrapropylammonium perruthenate as a catalyst Fetizon oxidation also a seldom used method uses silver carbonate supported on Celite This reagent operates through single electron oxidation by the silver cations nbsp Another method is the oxoammonium catalyzed oxidation Additionally sodium hypochlorite or household bleach in acetone has been reported for efficient conversion of secondary alcohols in the presence of primary alcohols Stevens oxidation 6 soluble transition metal complexes catalyze the oxidation of alcohols by presence of dioxygen or another terminal oxidant 7 Oxidation of diols edit nbsp Oxidative cleavage of carbon carbon bond in 1 2 diols Compounds possessing two hydroxy groups located on adjacent carbons that is vicinal diols 1 2 diols suffer oxidative breakage at a carbon carbon bond with some oxidants such as sodium periodate NaIO4 diacetoxyiodo benzene PhI OAc 2 8 or lead tetraacetate Pb OAc 4 resulting in generation of two carbonyl groups The reaction is also known as glycol cleavage Oxidation of primary alcohols to carboxylic acids edit nbsp When a primary alcohol is converted to a carboxylic acid the terminal carbon atom increases its oxidation state by four The direct oxidation of primary alcohols to carboxylic acids can be carried out using a variety of reagents Aldehydes are readily oxidized using Cr VI and Mn VII reagents to carboxylic acids Potassium permanganate edit Potassium permanganate KMnO4 oxidizes primary alcohols to carboxylic acids very efficiently This reaction which was first described in detail by Fournier 9 10 is typically carried out by adding KMnO4 to a solution or suspension of the alcohol in an alkaline aqueous solution For the reaction to proceed efficiently the alcohol must be at least partially dissolved in the aqueous solution This can be facilitated by the addition of an organic co solvent such as dioxane pyridine acetone or t BuOH KMnO4 reacts with many functional groups such as secondary alcohols 1 2 diols aldehydes alkenes oximes sulfides and thiols and carbon carbon double bonds Thus selectivity is an issue nbsp Ciufolini and Swaminathan 11 oxidized a primary alcohol to carboxylic acid with KMnO4 in aqueous NaOH during the obtention of a rare amino acid derivative needed for the preparation of antibiotics isolated from Actinomadura luzonensis a microorganism found in a soil sample collected in Luzon island in the Philippines Jones oxidation edit Main article Jones oxidation The so called Jones reagent prepared from chromium trioxide CrO3 and aqueous sulfuric acid oxidizes alcohols to a carboxylic acid The protocol frequently affords substantial amounts of esters 12 Problems are the toxicity and environmental unfriendliness of the reagent Catalytic variant involving treatment with excess of periodic acid H5IO6 have been described 13 nbsp Crimmins and DeBaillie 14 Two step oxidation of alcohols to acids via isolated aldehydes edit As a lot of the aforementioned conditions for the oxidations of primary alcohols to acids are harsh and not compatible with common protection groups organic chemists often use a two step procedure for the oxidation to acids The alcohol is oxidized to an aldehyde using one of the many procedures above This sequence is often used in natural product synthesis as in their synthesis of platencin 15 Niche methods and reagents edit Ruthenium tetroxide is an aggressive seldom used agent that allows mild reaction conditions Heyns oxidation 16 The use of chlorites as terminal oxidants in conjunction with both hypochlorites and TEMPO gives carboxylic acids without chlorination side products 17 The reaction is usually carried out in two steps in the same pot partial oxidation is effected with TEMPO and hypochlorite then chlorite is added to complete the oxidation Only primary alcohol oxidation is observed In conjunction with Sharpless dihydroxylation this method can be used to generate enantiopure a hydroxy acids 18 The Pinnick oxidation uses sodium chlorite 19 References edit Burton George et al 2000 Salters Advanced Chemistry Chemical 2nd ed Heinemann ISBN 0 435 63120 9 Chromium based Reagents Oxidation of Alcohols to Aldehydes and Ketones Basic Reactions in Organic Synthesis 2006 pp 1 95 doi 10 1007 0 387 25725 X 1 ISBN 0 387 23607 4 J C Collins W W Hess 1972 Aldehydes from Primary Alcohols by Oxidation with Chromium Trioxide Heptanal Organic Syntheses 52 5 doi 10 15227 orgsyn 052 0005 Dess D B Martin J C J Am Chem Soc 1991 113 7277 87 J S Yadav et al Recyclable 2nd generation ionic liquids as green solvents for the oxidation of alcohols with hypervalent iodine reagents Tetrahedron 2004 60 2131 35 Stevens R Chapman KT Weller HN 1980 Convenient and inexpensive procedure for oxidation of secondary alcohols to ketones Journal of Organic Chemistry 45 10 2030 2032 doi 10 1021 jo01298a066 Parmeggiani Camilla Cardona Francesca 2012 01 03 Transition metal based catalysts in the aerobic oxidation of alcohols Green Chemistry 14 3 547 564 doi 10 1039 C2GC16344F ISSN 1463 9270 Nicolaou KC Adsool VA Hale CR April 2010 An expedient procedure for the oxidative cleavage of olefinic bonds with PhI OAc 2 NMO and catalytic OsO4 Organic Letters 12 7 1552 5 doi 10 1021 ol100290a PMC 2848477 PMID 20192259 Fournier H M 1907 Transformation des alcools primaires satures en acides monobasiques correspondants C R Acad Sci 331 Fournier H M 20 July 1909 Sur la preparation des acides gras et de leurs anhydres Bull Soc Chim Fr 920 Ciufolini M A Swaminathan S 1989 Synthesis of a model depsipeptide segment of Luzopeptins BBM 928 potent antitumor and antiretroviral antibiotics Tetrahedron Lett 30 23 3027 doi 10 1016 S0040 4039 00 99393 6 Chromium based Reagents Oxidation of Alcohols to Aldehydes and Ketones Basic Reactions in Organic Synthesis 2006 pp 1 95 doi 10 1007 0 387 25725 X 1 ISBN 0 387 23607 4 Song Z J Zhao M Desmond R Devine P Tschaen D M Tillyer R Frey L Heid R Xu F Foster B Li J Reamer R Volante R Grabowski E J J Dolling U H Reider P J 1999 Practical Asymmetric Synthesis of an Endothelin Receptor Antagonist J Org Chem 64 26 9658 doi 10 1021 jo991292t Crimmins M T amp DeBaillie A C 2006 Enantioselective Total Synthesis of Bistramide A J Am Chem Soc 128 15 4936 7 doi 10 1021 ja057686l PMC 2546575 PMID 16608311 Nicolaou K C Scott Tria G Edmonds D J 2008 Total Synthesis of Platencin Angew Chem 120 9 1804 doi 10 1002 ange 200800066 Marcos Fernandez Gabriel Tojo 2006 Oxidation of Primary Alcohols to Carboxylic Acids A Guide to Current Common Practice Basic Reactions in Organic Synthesis Berlin Springer ISBN 0 387 35431 X Song Z J Zhao M Desmond R Devine P Tschaen D M Tillyer R Frey L Heid R Xu F Foster B Li J Reamer R Volante R Grabowski E J J Dolling U H Reider P J Okada S Kato Y Mano E J Org Chem 1999 64 9658 Sharpless K B Amberg W Bennani Y L Crispino G A Hartung J Jeong K S Kwong H L Morikawa K Wang Z M Xu D Zhang X L J Org Chem 1992 57 2768 Bal B S Childers Jr W E Pinnick H W 1981 Oxidation of a b unsaturated aldehydes Tetrahedron abstract 37 11 2091 doi 10 1016 S0040 4020 01 97963 3 Retrieved from https en wikipedia org w index php title Alcohol oxidation amp oldid 1219819818, wikipedia, wiki, book, books, library,

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