Amides amine oxidations, manganese dioxide

Nickel peroxide is a solid, insoluble oxidant prepared by reaction of nickel (II) salts with hypochlorite or ozone in aqueous alkaline solution. This reagent when used in nonpolar medium is similar to, but more reactive than, activated manganese dioxide in selectively oxidizing allylic or acetylenic alcohols. It also reacts rapidly with amines, phenols, hydrazones and sulfides so that selective oxidation of allylic alcohols in the presence of these functionalities may not be possible. In basic media the oxidizing power of nickel peroxide is increased and saturated primary alcohols can be oxidized directly to carboxylic acids. In the presence of ammonia at —20°, primary allylic alcohols give amides while at elevated temperatures nitriles are formed. At elevated temperatures efficient cleavage of a-glycols, a-ketols... 

Manganese dioxide conveits tertiary amines into amides. For exatiqrle, N,N-dimethylaniline gives N-methyl-N-phenylformamide in 78% yield and N-phenylpyrrolidine yields N-phenylformamide in 48% yield. 4 Dimethylaminocyclohexane on oxidation leads to cyclohexanone in 8S% yield. There is also... 

Carboxylic amides. Gilman has extended the procedure of Corey et at. (2, 261) for oxidation of allylic alcohols to carboxylic esters to the preparation of carboxylic amides. Thus oxidation of aromatic and a,/ -unsaturated aldehydes with Mn02 in the presence of sodium cyanide and an amine gives the corresponding carboxylic amides in high yield. In the absence of sodium cyanide, high yields of nitriles are formed from aldehydes, ammonia, and manganese dioxide. 

Such demethylation takes place often without interception of the form-amide. Dicyclohexylmethylamine, on treatment with potassium ferricya-nide in potassium hydroxide at room temperature overnight, is converted into dicyclohexylamine in 87% yield [926]. Other oxidants suitable for the demethylation of tertiary amines are mercuric acetate in 5% aqueous acetic acid at 100 °C [403], manganese dioxide in cyclohexane at 20 °C [812], and even oxygen, which, under irradiation at 20 °C in the presence of rose bengal in aqueous rm-butyl alcohol, converts codeine into norcodeine in 75% yield [46]. 

The oxidation of aldehydes in the presence of amines occurs at low temperatures with nickel perox-ide. Similarly, the oxidation of aromatic aldehydes with manganese dioxide or ruthenium chloride in the presence of sodium cyanide and an amine leads to the corresponding amides. 

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