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Hemithioacetal is an organic functional group with the general formula RCH(OR)SR. They form in a spontaneous reaction between a thiol and an aldehyde. Since the formerly carbonyl carbon bears four different substituents, hemiacetals are chiral. Hemithioacetals are usually intermediates in the catalytic reactions and usually arise via acid or base catalysis. The hemithioacetal features vicinal hydroxyl and thioether functionalities. Although they are important intermediates, hemithioacetals are usually not isolated since they exist in equilibrium with the thiol and aldehyde: :RCHO + R’SH RCH(OH)(SR’) ==Isolable hemithioacetal== Hemithioacetals ordinarily readily dissociate into thiol and aldehyde, however some have been isolated. In general these isolable hemithioacetals are cyclic, which disfavors dissociation, and can often be further stabilized by the presence of acid. An important class are S-glycosides, such as octylthioglucoside, which are formed by a reaction between thiols and sugars. Other examples include 2-hydroxytetrahydrothiophene and the anti-HIV drug Lamivudine. Another class of isolable hemithioacetals are derived from carbonyl groups that form stable hydrates. For example, thiols react with hexafluoroacetone trihydrate to give hemithioacetals, which can be isolated. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「hemithioacetal」の詳細全文を読む スポンサード リンク
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