Alcohols, oxidizing reagents alkylation

Methods of synthesis for carboxylic acids include (1) oxidation of alkyl-benzenes, (2) oxidative cleavage of alkenes, (3) oxidation of primary alcohols or aldehydes, (4) hydrolysis of nitriles, and (5) reaction of Grignard reagents with CO2 (carboxylation). General reactions of carboxylic acids include (1) loss of the acidic proton, (2) nucleophilic acyl substitution at the carbonyl group, (3) substitution on the a carbon, and (4) reduction. 

Common alcohol oxidation methods employ stoichiometric amounts of toxic and reactive oxidants like Cr03, hypervalent iodine reagents (Dess-Martin) and peracids that pose severe safety and environmental hazards in large-scale industrial reactions. Therefore, a variety of catalytic methods for the oxidation of alcohols to aldehydes, ketones or carboxylic acids have been developed employing hydrogen peroxide or alkyl hydroperoxides as stoichiometric oxygen sources in the presence of catalytic amounts of a metal catalyst. The commonly used catalysts for alcohol oxidation are different MoAV(VI), Mn(II), Cr(VI), Re(Vn), Fe(II) and Ru complexes . A selection of published known alcohol oxidations with different catalysts will be presented here. 

Progress from a synthetic point of view has been achieved in the selective oxidation of alkyl zinc reagents with oxygen in perfluoro-hexane solutions to give good yields of either hydroperoxides or alcohols. [28] As many zinc organometallics are easily obtained from olefins via a hydroboration/boron-zinc exchange sequence or by a nickel catalyzed hydro- or carbozincation reaction, this method may proof its synthetic potential in the future development. 

Selenium dioxide is probably the most common reagent used to selectively oxidize an alkyl fragment, and is particularly effective for converting allylic or benzylic C—H fragments to the corresponding allylic alcohol.522 In the most common applications, carbonyl derivatives are oxidized to 1,2-dicarbonyl compounds and allylic hydrocarbons to alcohols or esters. 23... 

The oligomeric iodosylbenzene sulfate 20 is a readily available, stable and water-soluble reagent with a reactivity pattern similar to that of activated iodosylbenzene [35-40]. It reacts with alkenes, alcohols and aryl alkyl sulfides in aqueous acetonitrile at room temperature to afford the respective products of oxidation 21-24 in good yields (Scheme 6.11) [35,36],... 

Heterogeneous catalysts offered fhe possibility to replace toxic reagents and reactants through the alkylation of amines or aromatics with alcohols instead of alkyl halides (reduction of salt production) the use of H2 instead of metals, metal hydrides, or sulfides and the replacement of metal oxides with H2O2 or O2. 

---