Alcohols, primary with nickel peroxide

In the presence of ammonia, some primary alcohols are oxidized to amides with nickel peroxide (equation 239) [1137. ... 

Whilst acetylenic alcohols can be employed directly in Cadiot-Chodkiewicz reactions [9], protection of the alcohol (usefully as the Thp ether) is necessary for Castro coupling [14]. A variation based upon these two processes involves coupling of terminal alkynes with 3-bromopropynol (10) in the presence of pyridine [15]. For primary alcohol products, oxidation to the aldehyde with nickel peroxide followed by base-catalyzed decarbonylation generates the new terminal acetylene e.g. Fig. 1.10. 

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... 

Aliphatic and aromatic aldehydes have been converted to the corresponding amides with ammonia or a primary or secondary amine, NBS, and a catalytic amount of AIBN (p. 935). " In a reaction of more limited scope, amides are obtained from aromatic and a,p-unsaturated aldehydes by treatment with dry ammonia gas and nickel peroxide. Best yields (80-90%) are obtained at —25 to —20°C. In the nickel peroxide reaction the corresponding alcohols (ArCH20H) have also been used as substrates. 

Nickel peroxide, an undefined black oxide of nickel, is prepared from nickel sulfate hexahydrate by oxidation in alkaline medium with an ozone-oxygen mixture [929] or with sodium hypochlorite [930, 931, 932, 933]. Its main applications are the oxidation of aromatic side chains to carboxyls [933], of allylic and benzylic alcohols to aldehydes in organic solvents [929, 932] or to acids in aqueous alkaline solutions [929, 930, 932], and of aldehydes to acids [934, the conversion of aldehyde or ketone hydrazones into diazo compounds [935] the dehydrogenative coupling of ketones in the a positions with respect to carbonyl groups [931] and the dehydrogenation of primary amines to nitriles or azo compounds [936]. 

This is a black, hydrous mixture of higher oxides of nickel made by treating nickel sulfate in alkaline solution with sodium hypochlorite. In alkaline solution, saturated aliphatic primary alcohols of adequate water-solubility are oxidized to the carboxylic acids (30°, 3-5 hrs.). Benzyl alcohol is oxidized by the alkaline reagent to benzoic acid, but with benzene as solvent and a slight excess of nickel peroxide it is oxidized to benzaldehyde. Allylic alcohols also can be oxidized to aldehydes by this method. 

This group is prepared by the reaction of the anion of 9-hydroxyanthracene and the tosylate of an aicohol. Since the formation of this group requires an SN2 displacement on the alcohol to be protected, it is best suited for primary alcohols. It is cleaved by a novel singlet oxygen reaction followed by reduction of the endo-peroxide with hydrqgen and Raney nickel.36... 

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