Oxidation of alcohols and ethers

Metal salts and complexes have also often been used as redox catalysts for the indirect electrochemical oxidation of alcohols. Particularly, the transformation of benzylic alcohols to benzaldehydes has been studies. For this purpose oxoruthe-nium(IV) and oxoruthenium(V) complexes have been applied as redox catalysts. In a similar way, certain benzyl ethers can be cleaved to yield benzaldehydes and the corresponding alcohols using a di-oxo-bridged binuclear manganese complex Electrogenerated 02(804)3 was used to generated 1-naphthaldehyde from 1-naphthylmethanol 

Aliphatic alcohols can be oxidized to ketones, aldehydes, or carboxylic acids using oxoruthenium(IV)complexes as redox catalyst or clectrogenerated ruthenium tetroxide In the latter case, a double mediator system is used in which an electrochemically generated active chlorine species (Cl or CP ) oxidizes RuO to RUO4 (Eq. (29)). 

The reaction takes place in a two-phase medium. Secondary alcohols form ketones (90%), primary alcohols and aldehydes are oxidized to carboxylic acids (60-77%), 1,2-diols are cleaved to carboxylic acids (75%), 1,4- and 1,5-diols are transformed to lactones and keto acids (75 %). 

Electrogenerated cerium(IV) sulfate is used to generate o-arabinose from D-gluconic acid (Eq. (30)) 

The oxidation of the primary hydroxyl groups in 3-phenyl-2-lV-acetylamino propanol and propargylic alcohol by electrogenerated chromic acid has been reported. jV-Acetylphenylalanin and propargylic acid are both formed in 90% current yield. 

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OXIDATION WITH BENZYLTRIMETHYLAMMONIUM TRIBROMIDE Oxidation of alcohols and ethers... 

Fig. 21. Reaction scheme for the oxidation of alcohols and ethers with BTMA Br3...

Ruthenium s versatility is due to the large range of accessible oxidation states, -1 to +8 [4], and different types of oxidation mechanisms that are operative, depending on the ruthenium source used (see later). The oldest application is probably the use of Ru04 for the oxidation of alcohols and ethers. 

Nwaukwa, S. O. and P. M. Keehn. 1982. The oxidation of alcohols and ethers using calcium hypochlorite. Tetrahedron Lett. 23 35-38. 

The monoalkyl ethers with R = CHj, CjHj and C4H, , known respectively as methyl ceUoaolve, ceUosolve and hutyl cellosolve, are of great commercial value, particularly as solvents, since they combine the properties of alcohols and ethers and are miscible with water. Equally important compounds are the carbitols (monoalkyl ethers of diethyleneglycol) prepared by the action of ethylene oxide upon the monoethers of ethylene glycol ... 

In acidic solution MnOj is usually the end product, although particularly vigorous reductants, e.g. iodide and oxalate ions, convert permanganate to manganous ions. Mn(III) is stable only in acidic solution or in the form of a complex, e.g. with pyrophosphate ion, and it has seldom been reported as the end product of a permanganate oxidation, e.g. for that of Mn(II) in a phosphate buffer and for those of alcohols and ethers in the presence of fluoride ion. ... 

Anodic Oxidation of Alcohols and Aliphatic Ethers 3.1.7.1 Electrosynthesis of Carboxylic Acids... 

Table 13 Oxidation of Alcohols and Silyl Ethers with PDC/Me3SiCI...

In the early 1970s, Barton et al. published the results of their woik on the oxidation of acetals and ethers by hy de transfer. o They observed that substituted benzyl ethers and benzyloxy carbonates, on brief exposure to trityl tetrafluoroborate in dichloromethane at 0 C followed by aqueous work-up, afforded go( yields of the parent alcohols together with the corresponding bennldehydes. Undw the same conditions, the tetrahydropyranyl ether of cholesterol was also efficiently deprotected. A mechanism was proposed which involved an initial hydrogen abstraction, followed by quenching of the resulting stabilized cation by water (Scheme 6). 

Oxidations. Oxidation of alcohols and their trimethylsilyl ethers at room temperature affords carbonyl products. Copper(ll) nitrate-dinitrogen tetroxide can also be used. 

The Oxidation of Alcohols, Ketones, Ethers, Esters and Acids in Solution... 

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