[PDF] [PDF] Oxidation

V Oxidation of Aldehydes and Ketones

tions to form carboxylic acids in high yields Furoic acid, for example, has Structurally more complex, insoluble substrates may be oxidized by Jones' reagent

[PDF] Aldehydes, Ketones and Carboxylic Acids - NCERT

The carbonyl carbon atom is sp2-hybridised and forms three sigma (σ) bonds The fourth Aldehydes and ketones are generally prepared by oxidation of primary may be aliphatic (RCOOH) or aromatic (ArCOOH) depending on the group,

Microbial Engineering for Aldehyde Synthesis - Applied and

lytic conversion of primary alcohols to aldehydes may provide an array of new opportunities for Villager oxidation to form esters (68), and Mannich reactions to

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Alcohols will burn in air to form carbon dioxide and water primary and secondary alcohols can be oxidised will be a colour change from orange to green Reaction mixture Aldehyde There may be more unusual examples in exams

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29 oct 2008 · Describe the oxidation of primary alcohols to form aldehydes and The equation for the oxidation of ethanol to the aldehyde ethanal is shown 

[PDF] 1 Alcohol Oxidations - CCC

2 avr 2006 · secondary alcohols to aldehydes and ketones at 25 °C It does not overoxidize to make it possible to oxidize alcohols in the presence of these Impure samples of Dess-Martin periodinane may in many cases provide better

[PDF] Oxidation

R' O alcohol ketone OH R H O aldehyde or Myers Chem 115 Oxidation O Ease of workup and at-or-near ambient reaction temperatures make the method salts may be formed in situ by the acid-promoted disproportionation of nitroxyl

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RONO R'' R' NCOR RCO 2 R' RSR'O RNO OH R'

RR'R''O

RR'R''OOH

RR'R''OOR'''

ROXO

NCNR'R

NNR'' 2 RR' O O R RNO R''' R'' RCX 2 R' SS RR' RCX 3 NNO R'R

R''R'''

ROSR'S

RR'N OR'' RR'N R'' CNR

RR'R''O

NR 2 O RR' Myers Oxidation States of Organic Functional GroupsGeneral Introductory References March, J. In Advanced Organic Chemistry, John Wiley and Sons: New York, 1992, p. 1158! 1238.
Carey, F. A.; Sundberg, R. J. In Advanced Organic Chemistry Part B, Plenum Press: New York,

1990, p. 615!664.

Carruthers, W. In Some Modern Methods of Organic Synthesis 3rd Ed., Cambridge University

Press: Cambridge, UK, 1987, p. 344!410.

Mark G. Charest, Jonathan William Medley

Chem 115Oxidation

The notion of oxidation state is useful in categorizing many organic tra nsformations. This is illustrated by the progression of a methyl group to a carboxylic acid in a series of 2-electron oxidations, as shown at right. Included are several functional group eq uivalents considered to be at the same oxidation state.

Alkane R-CH

3

Alcohol R-CH

2

OH (R-CH

2 X )

Aldehyde (Ketone) R-CHO (RCOR')

Carboxylic Acid R-CO

2 H

Carbonic Acid Ester ROH + CO

2 (ROCO 2

H)organometallics in general RCH

2

M (M = Li, MgX, ZnX...)

alkyl halide

X = halide

alkyl ether X = OR'alkylthio ether X = SR'alkylamine X = NR' 2 alkyl azide X = N 3 alkane sulfonate X = OSO 2 R' hemiketal (hemiacetal) ketal (acetal) dithianeoxime hydrazone geminal dihalide enol ether (enamine) ester orthoester nitrileketene trihalomethyl hydroxamic acid alkyl haloformate carbamatexanthate isocyanate carbodiimideaminal thioester amide urea Summary of Reagents for Oxidative Functional Group Interconversions: imineorganoboranes RCH 2 BR 2 organosilanes RCH 2 SiR 3 (OBO ester shown)R

R'(H)RR'

O alcoholketone OH RH O aldehyde or

Dimethylsulfoxide-Mediated Oxidations

Dess-Martin Periodinane (DMP)

o-Iodoxybenzoic Acid (IBX) tetra-n-Propylammonium Perruthenate (TPAP)

N-Oxoammonium-Mediated Oxidation

Manganese Dioxide

Barium ManganateOppenauer Oxidation

Chromium (VI) Oxidants

Sodium Hypochlorite

N-Bromosuccinimide (NBS)

Bromine

Cerium (IV) Oxidants

Sodium Chlorite

Silver Oxide

Potassium Permanganate

Pyridinium Dichromate (PDC)Bayer-Villiger Oxidation

Manganese Dioxide!NaCN!CH

3 OH

Bromine

ROH O acidR H O aldehydeR OR' O esterR H O aldehydeR OR' O esterR R' O ketone

Ruthenium Tetroxide

O 2 /Pt

Jones OxidationFetizon's Reagent

O 2 /Pt

N-Oxoammonium-

Mediated OxidationForm enolate; Davis OxaziridineForm enolate; MoOPHForm silyl enol ether; mCPBA ROH O acidR OH alcoholR O "-hydroxy ketoneR O ketonelactonediolR' OH R' O O n HO n OH O CH 31
RCH 2 OH(CH 3 2 SO H ROSCH 2 CH 3 H X(CH 3 2 S E -H ROH X(CH 3 2 S HH R OSCH 3 CH 3 X OOHCH 3HO H 3 COH H 3 C S Ph OH OOHCH 3HO H 3 COH H 3 C S

PhOAcH

O OBnHO HO (CH 3 2 S ROHH 2 CSCH 3 -H ROSCH 3 -BH -RCO 2- OTBSO TBSO H O OOHCH 3HO H 3 COH H 3 C S PhH OOHCH 3HO H 3 COH H 3 C S Ph OH HH R O AcOB

Dimethylsulfoxide-Mediated Oxidations

General Mechanism

Methylthiomethyl (MTM) ether formation can occur as a side reaction, b y nucleophilic attack of an alcohol on methyl(methylene)sulfonium cations generated from the di ssociation of sulfonium ylide intermediates present in the reaction mixture. This type of transformation is related to the

Pummerer Rearrangement.

+Dimethylsulfoxide (DMSO) can be activated by reaction with a variety o f electrophilic reagents, including oxalyl chloride, dicyclohexylcarbodiimide, sulfur trioxide, ac etic anhydride, and N- chlorosuccinimide. The mechanism can be considered generally as shown, where the initial st ep involves electrophilic (E ) attack on the sulfoxide oxygen atom. Subsequent nucleophilic attack of an alcohol substrate on the activated sulfoxonium intermediate leads to alkoxysulfonium salt formation. This intermediate breaks down under basic conditions to furnish the carbonyl compound and dimethyl sulfide.

Fenselau, A. H.; Moffatt, J. G. J. Am. Chem. Soc. 1966, 88, 1762!1765.Lee, T. V. In Comprehensive Organic Synthesis, Trost, B. M.; Fleming, I., Eds., Pergamon

Press: New York, 1991, Vol. 7, p. 291!303.

Tidwell, T. T. Synthesis 1990, 857!870.

Tidwell, T. T. Organic Reactions 1990, 39, 297!557. Mark G. Charest, Jonathan William Medley• Reviews • Pummerer Rearrangement CF 3 CO 2

Ac, Ac

2 O

2,6-lutidine

>60% Schreiber, S. L.; Satake, K. J. Am. Chem. Soc. 1984, 106, 4186!4188.

Swern Procedure

Typically, 2 equivalents of DMSO are activated with oxalyl chloride in dichlorome thane at or below -60 °C. Subsequent addition of the alcohol substrate and triethylamine leads to carbonyl formation. The mild reaction conditions have been exploited to prepare many sensiti ve aldehydes. Careful optimization of the reaction temperature is often necessary. Huang, S. L.; Mancuso, A. J.; Swern, D. J. Org. Chem. 1978, 43, 2480!2482. 66%
Evans, D. A.; Carter, P. H.; Carreira, E. M.; Prunet, J. A.; Charette, A. B.; Lautens, M. Angew. Chem., Int. Ed. Engl. 1998, 37, 2354!2359.1. TBSCl, Im, DMAP, CH 2 Cl 2

2. 10% Pd/C, AcOH, EtOAc

3. (COCl)

2 , DMSO; Et 3 N -78 " -50 °C 99%

100-g scale(COCl)

2 , DMSO; Et 3

N, -78 °C

Fang, F. G.; Bankston, D. D.; Huie, E. M.; Johnson, M. R.; Kang, K.-C.; LeHoull ier, C. S.; Lewis, G.

C.; Lovelace, T. C.; Lowery, M. W.; McDougald, D. L.; Meetholz, C. A.; Partridge, J. J.; Sharp, M. J.;

Xie, S. Tetrahedron 1997, 53, 10953!10970.•

alkoxysulfonium ylide+

RR'(H)RR'

O alcoholketoneOH RH O aldehyde or

MyersChem 115Oxidation

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