Mercaptans


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Mercaptans

 

thioalcohols, thiols, sulfur analogues of alcohols, general formula, RSH, where R is a hydrocarbon radical.

With the exception of methyl mercaptan (boiling point, 6.0°C), the mercaptans are liquids with an unpleasant specific odor. They occur in nature mainly in the products of protein decay. Their weakly acidic properties make mercaptans capable of forming salts, called mercaptides [for example, of mercury— (RS)2Hg—hence the name, from the Late Latin mercurium captans,“mercury-binding”]. Mercaptans are easily oxidized to disulfides (RSSR) and sulfonic acids (RSO3H).

Mercaptans are prepared by the alkylation of hydrosulfides of the alkaline metals: NaSH + RX → RSH + NaX (where R is alkyl and X is a halogen). They are also obtained by the condensation of thiourea S = C(NH2)2 with alkyl halides (RX), followed by the hydrolysis of the resultant S-alkylisothiouronium salts. Thiophenols are also frequently included among the mercaptans.

Mercaptans and their derivatives (salts, sulfides, and disulfides) are used as accelerators in the vulcanization of natural and synthetic rubbers (for example, 2-mercaptobenzothiazole, or Kaptaks), as accelerators in the plastication of rubbers (for ex-ample, pentachlorothiophenol, or Renatsit, and dodecyl mercaptan), in certain medicinal preparations (methionine, Sulfonal), and in insecticides. A mixture of mercaptans (mostly of butyl and amyl mercaptans) is used to add an odor to harmful odorless gases.

References in periodicals archive ?
The authors review the properties and applications of mercaptans (thiols) in organic synthesis, then describe the composition and properties of C2-C5 mercaptans in a mixture of national origins and describe the synthesis of other materials, explain the synthesis and transformation of functionally situated acids and the synthesis and transformation of products of thioalkylatin of mercaptans C2-C5, testing of applied properties of organic compounds synthesized on the base of the C2-C5 mercaptans mixture, and methods of carrying out experiments.
Merichem, through its wholly owned subsidiary Merichem Chemicals and Refinery Services (MCRS), provides the management of caustic streams ranging from technology for on-site treatment to the purchase and beneficial reuse of the caustic streams; development, engineering, fabrication and licensing of innovative technologies for the removal of hydrogen sulphide, mercaptans and other impurities from hydrocarbon streams; and the production of catalysts for treating processes and naphthenic chemicals for a variety of industries.
The processing of this liquid is necessary because it has a high content of sulphurous mercaptans.
The Environment Agency said Seaport Environmental has not accepted any more waste containing mercaptans, a chemical used to odorise natural gas.
There are a number of chemical and physical phenomena that can give rise to depletion of the concentration of odorants, particularly mercaptans, in natural gas or LPG.
5 of this source for the class of alkyl halides, mercaptans, sulphides and disulphides.
Located at 2231 Haden Road in Houston and 2810 Gulf States Road in Beaumont, ATOFINA's Houston and Beaumont facilities employ 145 people and manufacture mercaptans and dimethyl sulfide.
mercaptans that reacted with the carbon-carbon bonds.
In particular, several components need to be eliminated (water from digesters or ventilation shafts and landfill collection systems, compounds such as hydrogen sulfide (H2S) or mercaptans, as well as siloxane, which corrodes gas engines).
Mercaptans are used to odorisenatural gas as an early warning system for leaks.
In order to help prevent such a tragedy from ever happening again, Texas began mandating that mercaptans be added to natural gas to "warn" individuals of its presence.
Alkanesulfonic acids used as catalysts and solvents in organic synthesis, as salts in pharmaceutical ingredients, and as reagents and intermediates; -- Alkanesulfonyl chlorides and sulfonamides used as reagents and intermediates to produce fine chemicals; -- Alkyl amines, alkylalkanol amines and hydroxyl amines as acid scavengers, catalysts, reagents, intermediates; -- High purity bromine derivatives used in pharmaceutical, agricultural, electronic and intermediate synthesis applications, Friedel-Crafts reactions, cyanations, esterifications; -- Dimethyl sulfoxide used as a solvent for reactions and processing; -- Mercaptans and sulfides used as odorants, chain-transfer agents and refinery chemicals.