Alcohols sulfur analogs

Sulfides (RSR ) are the sulfur analogs of ethers Just as m the preceding chapter where we saw that the properties of thiols (RSH) are different from those of alcohols we will explore differences between sulfides and ethers m this chapter... 

Compounds with a smaller/C., and larger pKa are less acidic, whereas compounds with a larger/Ca and smaller plsimple alcohols like methanol and ethanol are about as acidic as water but substituent groups can have a significant effect, tert-Butyl alcohol is a weaker acid, for instance, and 2,2,2-trifluoroethanol is stronger. Phenols and thiols, the sulfur analogs of alcohols, are substantially more acidic than water. 

Thiols (R—S—H) and sulfides (R—S—R ) are sulfur analogs of alcohols and ethers, respectively. Both functional groups are found in various biomolecules, although not as commonly as their oxygen-containing relatives. 

Thiols, sometimes called mercaptcms, are sulfur analogs of alcohols. They are named by the same system used for alcohols, with the suffix -thiol used in place of -ol. The -SH group itself is referred to as a rnercapto group. 

Sulfides are the sulfur analogs of ethers just as thiols are the sulfur analogs of alcohols. Sulfides are named by following the same rules used for ethers, with sulfide used in place of ether for simple compounds and alkylthio used in place of alkoxy for more complex substances. 

Thiols, the sulfur analogs of alcohols, are usually prepared by Sjv 2 reaction of an alkyl halide with thiourea. Mild oxidation of a thiol yields a disulfide, and mild reduction of a disulfide gives back the thiol. Sulfides, the sulfur analogs of ethers, are prepared by an Sk2 reaction between a thiolate anion and a primary or secondary alkyl halide. Sulfides are much more nucleophilic than ethers and can be oxidized to sulfoxides and to sulfones. Sulfides can also be alkylated by reaction with a primary alkyl halide to yield sulfonium ions. 

Also called mercaptans, these compounds, with the generic formula RSH, are sulfur analogs of alcohols, just as HjS is of HjO. The O atom of the OH has been replaced by an S atom, and the — SH group is denominated sulfhydryl. 

Hydrogen sulfide ion (HS ) Use of hydrogen sulfide as a nucleophile permits the conversion of alkyl halides to compounds of the type RSH. These compounds are the sulfur analogs of alcohols and are known as thiols. 

Sulfur occurs directly beneath oxygen in the periodic table, and, like oxygen, it often exhibits a valence of two. Therefore, sulfur analogs of alcohols and ethers are often encountered. However, because sulfur is in the third period of the periodic table, it can also have a higher valence. Structures with four or six bonds to a sulfur are common. In organic chemistry the most important of these expanded valence compounds have the sulfur bonded to one or two extra oxygens. 

Thiols are the sulfur analogs of alcohols. They have high binding energy to a gold surface and form self-assembled monolayers, which are molecular assemblies that are prepared by spontaneous adsorption of thiols from solution onto a gold substrate [i, iii]. 

Thiols (sulfur analogs of alcohols) are named by the same system as alcohols, with the suffix -thiol replacing -ol. 

Sulfide and selenide precursors for 2,3-rearrangements can be obtained stereochemically pure by chal-cogeno-etherifications (equation 78). From these precursors thio-(211) and seleno-(211) were prepared by oxidation. While the sulfoxide refused to rearrange to alcohol (212) under various conditions, the selenoxide did so even at 0 °C. Here, the extra driving force of selenoxide vs. sulfoxide rearrangements was an essential it pushed the selenoxide through a transition state obviously too sterically hindered for the less reactive sulfur analog. 

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