Thiols Mercaptans

Reduction of carbonyl compounds (Section 10-11) a. Catalytic hydrogenation of aldehydes and ketones 

This method is usually not as selective or as effective as the use of hydride reagents. 

Thiols are sulfur analogues of alcohols, with an —SH group in place of the alcohol —OH group. Oxygen and sulfur are in the same column of the periodic table (group VIA), with oxygen in the second row and sulfur in the third. lUPAC names for thiols are derived from the alkane names, using the suffix -thiol. Thiols are also called mercaptans ( captures mercury ) because they form stable heavy-metal derivatives. 

Common names are formed like those of alcohols, using the name of the alkyl group with the word mercaptan. The —SH group itself is called a mercapto group. 

Offensive use of thiols. Skunks spray thiols to protect themselves from people, dogs, and other animals. 

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Early examples of such branched polysulphides, e.g. Thiokol FA, are believed to possess hydroxyl end groups and are coupled by means of zinc compounds such as the oxide, hydroxide, borate and stearate by a mechanism which is not understood. Later elastomers, e.g. Thiokol ST, have been modified by a restricted reductive cleavage (see below) and this generates thiol (mercaptan) end groups. These may be vulcanised by oxidative coupling as illustrated below with lead peroxide ... 

Fairchild EJ, Stokinger HE Toxicologic studies on organic sulfur compounds. 1. Acute toxicity of some aliphatic and aromatic thiols (mercaptans). Am Ind Elyg Assoc J 19 171-189, 1958... 

Methanethiol Methyl Mercaptan Thiols, Mercaptans Thiols, Sulfides, and Disulfides Thorium Tin... 

Substituents attached to a heterocyclic ring through a sulfur atom exist in wider variety than those through oxygen. Besides the simple thio analogues—the thiols (mercaptans), thioethers, thioesters and the like—they include compounds of various higher oxidation states of sulfur, including sulfoxides, sulfones, sulfinic and sulfonic acids and their derivatives. 

A summary of the work on the identification of sulfur compounds in crude oils has been given recently by Ball, Rail, Waddington, and Smith (31), who list the sulfur compounds isolated from petroleum by earlier investigators and, in addition, give several new compounds which have recently been isolated from a Wasson, Tex., crude petroleum by the API Research Project 48. Birch and Norris (5) isolated a substantial number of the thiol (mercaptan) type of sulfur compounds from an Iranian crude petroleum. 

Dehydrosulphidation of thiols and sulphides is directly analogous to dehydration of alcohols and ethers. Thiols (mercaptans) yield both alkenes and sulphides... 

Know the meaning of thiol, mercaptan, mercaptide, sulfhydryl group, disulfide. 

Substitution of alkyl or aryl hydrocarbon groups, such as phenyl and methyl for H on hydrogen sulfide, H2S, leads to a number of different organosulfur thiols (mercaptans, R-SH) and sulfides, also called thioethers (R-S-R). Structural formulas of examples of these compounds are shown in Figure 1.19. 

Mechanism 10-2 Hydride Reduction of a Carbonyl Group 454 Summary Reactions of LiAIH4 and NaBH4 455 Summary Alcohol Syntheses by Nucleophilic Additions to Carbonyl Groups 457 10-12 Thiols (Mercaptans) 458 EssentialTerms 461 Study Problems 462... 

Thiols are sulfur analogues of alcohols, with an —SH group in place of the alcohol Thiols (Mercaptans) —OH group. Oxygen and sulfur are in the same column of the periodic table (group 6A),... 

Sodium sulfhydride (NaSH) is a much better reagent for the formation of thiols (mercaptans) from alkyl halides than H2S and is used much more often. It is easily prepared by bubbling H2S into an alkaline solution, but hydrosulfide on a supported polymer resin has also been used. " The reaction is most useful for primary halides. Secondary substrates give much lower yields, and the reaction fails completely for tertiary halides because elimination predominates. Sulfuric and sulfonic esters can be used instead of halides. Thioethers (RSR) are often side products. The conversion can also be accomplished under neutral conditions by treatment of a primary halide with F and a tin sulfide, such as PhsSnSSnPhs. An indirect method for the preparation of a thiol is the reaction of an alkyl halide with thiourea to give an isothiuronium salt (119), and subsequent treatment with alkali or a... 

Chemical/Pharmaceutical/Other Class Thiol Mercaptan... 

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