Ionic Hydrogenation

Papers on the ionic hydrogenation of a double bond, consisting in the successive addition of a proton and a hydride ion, are surveyed. The use of trifluoroacetic acid as donor of the proton and of triethylsilane as donor of the hydride ion has permitted the hydrogenation of alkenes, dienes, cyclopropane hydrocarbons, saturated and unsaturated ketones, aldehydes, quinones, and anils. Each class of compounds shows selectivity on ionic hydrogenation with the above pair of hydrogenating agents. The reaction extends to single bonds in the case of disulphides and ethers, which undergo ionic hydrogenolysis. Ideas on the mechanism of ionic hydrogenation are examined. The bibliography includes 58 references.