Mercaptocarboxylic acids

Oxathiolones are formed by heating a ketone with the mercaptocarboxylic acid in the presence of TsOH. They are cleaved by either acid (TFA, H2O, THF) or base (NaOH, acetone) hydrolysis. ... 

More extensive studies have shown that a-mercaptocarboxylic acids, ethyl nitrite, and iVJV -dicyclohexylcarbodiimide with a catalytic amount of sulfuric acid yield meso-ionic l,3,2-oxathiazole-5-ones (169), presumably via intermediate 5-nitroso derivatives (170). 

Chaudiere, J., Wilhelmsen, E. C., and Tappel, A. L. (1984). Mechanism of selenium-glutathione peroxidase and its inhibition by mercaptocarboxylic acids and other mercaptans. J. Biol. Chem. 259, 1043-1050. 

Among other mercaptocarboxylic acids, the mercaptopropionic acids have undergone a promising development. Thiolactic acid or 2-mercaptopropionic acid [79-42-5], HSCH(CH3)COOH, is manufactured by using 2-chloropropionic acid [598-78-7]. 3-Mercaptopropionic acid [107-96-0], HSCH2CH2COOH, competes with thioglycolic acid in plastic additives or as modifiers in various polymers. Mercaptopropionic acid is... 

Economic Aspects Since its development in cosmetics in the 1940s, thioglycolic acid has become a widespread thiochemical, used all over the world as the acid or in the form of its salts or esters. Because of the several derivatives of thioglycolic acid used, the market size for this chemical is often expressed in terms of thioglycolic acid equivalents. In 1994 the total world market was estimated at around 15,000 to 20,000 metric tons of thioglycolic acid equivalents. Some mercaptocarboxylic acid and esters available are compiled in Table 2. Table 2. Mercaptocarboxylic Esters Derivatives ... 

Various polymers, such as polythiourethanes, polythioethers, and polythioacrylates, are used to produce resins which are transparent, colorless and have a high refractive index and good mechanical properties, useful for the production of optical lenses. Higher refractive indices are promoted by sulfur compounds and especially by esters of mercaptocarboxylic acids and polyols such as pentaerythritol (41) (see Polymers containing sulfur). 

Thioglycolic acid is recommended as a cocatalyst with strong mineral acid in the manufacture of bisphenol A by the condensation of phenol and acetone. The effect of the mercapto group (mercaptocarboxylic acid) is attributed to the formation of a more stable carbanion intermediate of the ketone that can alkylate the phenol ring faster. The total amount of the by-products is considerably reduced (52). 

Dioiganotin dihalides are moderately strong Lewis acids and form stable complexes with ammonia and amines. The commercially important diorganotin compounds are most frequently the oxides, carboxylates, and mercaptocarboxylic acid esters. The oxides are amorphous or polycrystalline, highly polymeric, infusible, and insoluble solids. They are moderately strong bases and react readily with a wide variety of strongly and weakly acidic compounds. Their insolubility in all nonreactive solvents makes the choice of proper reaction conditions for such a neutralization reaction an important consideration for optimum yields. 

The reaction of a -mercaptocarboxylic acids (347) with dicyanogen affords good yields of 4,4 -dioxo-2-bithiazolinyl (349 Scheme 222) (69JOC2053). 

Similarly, 2,3-dihydro-5-oxo-thiazolo[3,2-a]pyridine-3,7-dicarboxylic acids are formed in the reaction between a-amino-/3-mercaptocarboxylic acids with citric acid. In the reaction of (S)-penicillamine the cyclic product (501) was reported to be racemized (71T3447). 

Dioxathiolan-4-one 2-oxides (50) decompose rapidly in the presence of water and mineral acids to form a-hydroxy carboxylic acids, the detailed mechanism of hydrolysis being unknown. Nucleophilic attack on (50) by alcohols occurs at the acyl carbon atom and, with elimination of sulfur dioxide, gives a-hydroxy carboxylic acid esters (76CRV747). In a similar fashion to (50), l,2,3-oxadithiolan-5-one 2-oxides react rapidly with water to yield the parent a-mercaptocarboxylic acids (77MI43301). 

Comprehensive review chapters on 1,3-oxathiolium salts <02MI35> and 1,3-oxaselenolium salts <02MI93> have appeared. Scandium triflate has been introduced as an efficient catalyst for reaction of aldehydes with mercaptoethanol to form 2-substitued 1,3-oxathiolanes <03S2503>. Protection of a-mercaptocarboxylic acids is readily achieved by... 

The sensitivity of Si chemical shifts to structural changes and the technique of silylating compounds for more favourable analysis or synthesis have been combined by several researchers to produce a powerful structure elucidation technique for monofunctional or polyfunctional compounds. (135-141) Specifically, the trimethylsilyl derivatives of imidophosphoryl compounds, (141) sugars, (138-140) steroids, (140) amines, amides, and urethanes, (135,136) and amino-, hydroxy-, and mercaptocarboxylic acids (137) have all been studied within the past three years. 

Haptens containing amino groups can be coupled directly to carriers containing carboxyl groups, or the amino group can be converted to a carboxylic acid by reaction with succinic anhydride. - When a keto or an aldehyde group is present in the hapten, it can be converted to a carboxyl via reaction with 0-(carboxymethyl)hydroxylamine or with hydrazides. Haptens containing double bonds can be made to react directly with mer-captoacetic or mercaptopropionic acid, or a two-step reaction may be performed bromination followed by reaction with mercaptocarboxylic acid. ... 

The first (3-thiolactone was prepared according to Scheme A by Knunyants and co-workers. A mixed anhydride of )3-mercaptocarboxylic acid and carbonic-acid ester is obtained by treatment of a salt of the mercapto acid with a chlorocarbonate ester.Cyclization to the 3-thiolactone occurs during the reaction this synthetic method is exemplified by the preparation of 302 from 301. A mixed carboxylic-sulfonic acid anhydride is involved in the formation of the thiolactone ring in 303. ... 

Finally, it should be mentioned that y- and 8-thiol lactones are in many cases formed simply by heating the corresponding mercaptocarboxylic acids or by treating them with phosphorus pentoxide. The P-thiolactone (20) has also been obtained by flash pyrolysis of 3-mercapto-2-naphthoic acid (equation IS). - ... 

Mercaptoacetic acid s. Thioglycolic acid Mercaptocarboxylic acids... 

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