Chem. [arbitrarily f. THIO-] A name for the group SH in combination, analogous to hydroxyl, OH.
It indicates the presence of an -SH group (or an -SR group, where R is an alkyl radical), as in methyl-thiolcarbamate, H2N.CO.SCH3, as distinguished from methyl carbamate, H2N.CO.OCH3, and also from methyl-thion-carbamate, H2N.CS.OCH3: see THION-. Also, in those cases in which hydroxy- would mean the presence of an -OH group, thiol- indicates the presence of an -SH group; and where methoxy-, ethoxy-, etc., would indicate CH3O-, C2H5O-, RO- groups, methylthiol-, ethylthiol-, R-thiol-, indicate CH3S-, C2H5S-, RS- groups; thus, the sulphur compound corresponding to sodium ethoxyacetate C2H5O.CH2.CO2Na is sodium ethylthiolacetate C2H5S.CH2.CO2Na. Cf. THION-.
1899. Jrnl. Chem. Soc., LXXVI. I. 797. The authors adopt the Geneva nomenclature, thion being used to denote compounds containing the group .CS.OR, and thiol those containing the group .CO.SR. Ibid. (1905), LXXXVIII. I. 626. α-Thiolbutyric acid, SH.CHEt.CO2H, is an oil boiling at 118–122° under 19 mm. pressure.
