Acetyl mercaptan

Synonyms/Trade Names Acetyl mercaptan, Mercaptoacetate, Mercaptoacetic acid, 2-Mercaptoacetic acid, 2-Thioglycolic acid, Thiovanic acid ... 

Since the original observation of Lipmann et cd. (1947) on the presence of pantothenic acid in coenzyme A, the purification and chemical structure of the coenzyme has been the subject of intensive investigation in many laboratories (Snell et al., 1950 Lynen and Reichert, 1951 Novell et al, 1951 Baddiley and Thain, 1951). As formulated at present, coenzyme A contains 1 adenine, 1 ribose, 1 sulfur, and 3 phosphates per pantothenate. Evidence presented by Lynen and Roichert (1951) indicates that acetyl-CoA, which is now considered synonomous with active acetate, is an acetylated mercaptan. A tentative structure of acetyl-CoA is given below. 

Using this procedure, the S-labeled rhena-/8-ketoimine derivatives of benzyl mercaptan, ethanethiol, Me3COC(O)NH0H2CH2SH, iV-acetyl-L-cysteine, and iV-acetyl-D,L-penicillamine have been prepared. 

In addition, another organosulfur compound, S-allyl-mercaptocysteine (Fig. 2) has been shown to affect histone acetylation levels. This again is probably due to its ability to form allyl mercaptan upon metabolic reduction of its disulfide bond. ... 

B. Preparation of acetanilide. Since ketene is a highly reactive gas, it is usually prepared for immediate consumption instead of being isolated as such. It reacts with various groups which contain hydrogen, such as hydroxyl, amino, mercaptan, hydroxylamino, etc., forming acetyl derivatives. 

Base-catalyzed condensation of 2-(acetyl)thioindoxyl with aromatic aldehydes affords compounds with the general formula 330, which give the adducts 331 with aryl mercaptans in the presence of piperidine.582... 

The same procedure is used for the formation of resins 2 and 8 by reaction of the nitroarenes with the resin-bound [3-alanine or mercaptan/ amine linker, respectively. The o-fluoronitroarenes (Fig. 3) are dissolved in DMSO or NMP (at a concentration between 1.5 and 2 M) and added to the resin, followed by diisopropylethylamine (10 equivalents) and additional DMSO or NMP (if required) to ensure resin solvation. Although many nitroarenes react rapidly at room temperature, in a library format the resin/nitroarene mixture is heated overnight at 50° to help achieve equivalent reaction kinetics between different monomers. Under the same conditions, some o-chloronitroarenes are synthetically useful. The extent of the reaction can be assessed qualitatively (or quantitatively, if desired) by carrying out a ninhydrin test to check for the presence of free amine. In any case, the resins are acetylated with five equivalents of acetic anhydride/pyridine/DMF (1 1 10) for 20 min to cap any unreacted amine. 

Although the penta-O-acetyl derivatives of /3-D-glucopyranose and /3-D-galactopyranose underwent rapid mercaptolysis at 0° in ethyl mercaptan (with zinc chloride as catalyst) to yield the corresponding ethyl tetra-0-acetyl-l-deoxy-l-thio-/3-D-glycopyranosides, the a-forms of these... 

Mercaptolysis of /3-D-glucopyranose pentaacetate in ethyl mercaptan at 0°, with zinc chloride as catalyst, gives ethyl tetra-O-acetyl-l-deoxy-1-thio-/S-D-glucopyranoside in 71% yield. Under the same conditions, a-D-glucopyranose pentaacetate reacted only very slowly, but it could be shown that the deoxy-thio-/3-D-glucoside is formed in much greater amount than is the a anomer. Mercaptolysis of the D-mannopyranose pentaacetates under the same conditions for 48 hours resulted in a 70% yield of ethyl tetra-O-acetyl-l-deoxy-l-thio-a-D-mannopyranoside from the /3-D-pentaacetate, and in a 60% yield from the a anomer.103 Inspection, by preparative paper chromatography, of the residual sirups, after deacetylation, led in each case to the isolation of the anomeric ethyl-1-... 

Contrary to the mass spectra of mercaptans or disulfides, however, the mass spectra of various thioether compounds (e.g. 8, JL 2 and 1 5) show no loss of an acetyl... 

MERCAPTANS l-Acetyl-2-thiouiea. METHANESULFONATE ESTERS Meth-anesulfonyl chloride. 

Cleavage of streptomycin with ethyl mercaptan and hydrogen chloride yielded streptidine and a new derivative of streptobiosamine, ethyl thio-streptobiosaminide hydrochloride diethyl mercaptal. Treatment of methyl streptobiosaminide hydrochloride dimethyl acetal with ethyl mercaptan and hydrogen chloride readily yielded the same mercaptal hydrochloride. It thus was apparent that the relationship between these two compounds resided simply in the replacement of methoxy by thio-ethoxy groups on the same carbon skeleton. Acetylation of the mercaptal yielded two anomeric forms of ethyl tetraacetylthiostreptobiosaminide diethyl mercaptal. ... 

Synthesis of mercaptans.1 Mercaptans can be obtained in 30-75 % yield by heating (I) with an alkyl halide in ethanol for 24 hr. Acetylurea (3) is the other product. An intermediate l-acetyl-2-alkyl-2-thiopseudourea hydrohalidc (a) is involved. These thiopseudoureas can be isolated if prepared in acetonitrile solution. Yields of mercaptans are high when primary halides are used but rather low in the case of secondary... 

Acetylation. The reagent, neat or in nitromethane solution, acylatcs aromatic compounds in good yield (I). It is an effective reagent for O-acetylation of alcohols (2), for S-acetylation of mercaptans, and for N-acetylation of primary and secondary amides. 

Stir gently during 30 min al room temperature. The acetyl group of the AMSA keeps the thiol protected during coupling to the macromolecule until one wishes to expose the mercaptan for further reactions (following steps). 

Reactions of acetyl chloride that are formally analogous to hydrolysis occur with alcohols, mercaptans, and amines primary or secondary compounds form corresponding acetates or amides tertiary alcohols generally yield the tertiary alkyl chlorides. Acetyl chloride can split the ether linkages of many ordinary ethers and acetals. It equilibrates with fatty acids to provide measureable amounts of the mixed acetic—alkylcarboxylic anhydride or acyl chloride, either of which may be employed in esterifications. For example, lauric acid [143-07-7], and acetyl chloride undeigo the reactions... 

A series of alkyl and aryl mercaptan-tail porphyrins has been prepared by Collman and Groh (Scheme 28) The Cs alkyl chain may be prepared directly by treating mono-(o-aminophenyl)triphenylporphyrin (57) with S-acetyl or S-tritylthiohexanoyl chloride... 

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