Effects of phenyl and alkyl substitutions on the hydrogenation of allene with diimide

Studies on the mechanism of the hydrazine reduction reaction: Applications to selected monoethylenic, diethylenic and triethylenic fatty acids ofcis configurations

“…The above relative rates for the hydrogenation of monoethylenic acids with hydrazine are of interest not only in their own intrinsic way, but also because they permit some comments to be made on the mechanism of the reaction. It is known that steric effects are an important factor in this reaction (1,10); however, electronic effects are said to have little effect (1), although this is not so in the case of allenes (10). It should be noted that this paper (10) is concerned with "diimide" generated by decomposition ofp-toluenesulfonylhydrazide.…”

“…In the first instance, the ease of hydrogenation at any position in a fatty acid chain is undoubtedly modified by steric factors. These factors are important in this reaction (1,2,10). A double bond at the center of a chain would be more sterically hindered than one toward either end of a chain, especially if there is a predominance of gauche conformations in the chain as might be expected in a polar solvent such as ethanol, but the ends of a chain should experience roughly comparable steric hindrance.…”

“…The use of hydrazine for the reduction of ethylenic (olefinic) bonds has been known for almost eighty years and is believed to involve the intermediacy of diimide (HN=NH, [1 ]), a reactive species that first excited considerable attention some twenty years ago (1,2). A range of papers describing calculations on (3)(4)(5)(6)(7), or properties of (8)(9)(10), diimide is evidence of a continuing interest in unravelling the chemistry of this species. The hydrazine reduction reaction has found favor for reductions of unsaturated fatty acids (11)(12)(13) because no apparent cistrans isomerism or ethylenic bond positional shifts occur, in strong contrast to the results from the use of catalytic hydrogenation (14).…”

The preparation, properties and reactions of diimide

“…Relative rates of reaction with a large variety of unsaturated compounds have been reported [7,9,14,15,91,124,131,133,136,137,[141][142][143][144] from various laboratories. These data are semi-quantitative at best; some are based simply on yields of reduction products from single reagents under some standard conditions of diimide generation; others are derived from the competitive reduction of pairs of reagents.…”

Reductions of CC and CC by Noncatalytic Chemical Methods

“…3D The reaction shown in equation (13) illustrates the use of this procedure to reduce the highly reactive endoperoxide (32) Diimide reductions can be carried out in the presence of reactive functional groups including allylic halides,23.24 esters,23 amines 23 and disulfides.…”