ABSTRACT
Reduction, substitution, and oxidation are the major types of reactions which can occur on the sulfur atom. The number of systematic studies of reduction is small considering its enormous importance in chemical synthesis and in biological phenomena. Disulfides are reduced by the powerful reducing agent, lithium aluminum hydride. In addition to thiols, a nearly quantitative amount of hydrogen gas is formed on warming. Thiols are mild reducing agents and readily reduce RSX to the disulfide. For example, thiophthalimides react rapidly with thiols to afford unsymmetrical disulfides. RSX are reduced to thiols by reduction at an electrode. Lithium aluminum hydride can reduce sulfinic acids to thiols in excellent yields. Hydrazine cannot reduce the sulfinic acid directly because of salt formation. However, sulfinic esters and halides are reduced to the corresponding disulfides nearly quantitatively. Sulfinic acids are reduced by thiols to the corresponding disulfides under mild conditions.
