Mercapto esters

Polyhydric alcohol mercaptoalkanoate esters are prepared by reaction of the appropriate alcohols and thioester using -toluenesulfonic acid catalyst under nitrogen and subsequent heating (16,17). Organotin mercapto esters are similarly produced by reaction of the esters with dibutyltin oxide (18). Pentaerythritol can be oxidized to 2,2-bis(hydroxymethyl)hydracryhc acid [2831-90-5] C H qO, ... 

A problem associated with the use of abrasive metal poHshes is that the fresh metal, which has been exposed by the cleaning, rapidly oxidizes or tarnishes. Thus, many modem poHshes contain inhibitors. Sulfur compounds, eg, alkyl benzyl thiols, commonly are used, as are mercapto esters such as lauryl thioglycolate [3746-39-2] and dialkyldisulfides (52—54). 

A very dramatic increase in the effectiveness of an in-register mercaptan inhibitor is achieved by the attachment of a second chelating moiety at the carbon atom a to the mercaptan Table 8.13). The mercapto-ester (130) can act as a bidentate ligand for the active site Zn(II) and, with an IC50 of 3.9 nM, it is some 50-fold more potent than the corresponding a-methylmer-captan (121) note, however, that the collagenase sources are different in the two cases. 

Alkyl and aryl /i-mercaptohydrocinnamates (64) have been prepared by the reaction shown in Scheme 4. The yellow Cu1 and red Ni11 complexes were characterized.257 The a,/ -unsaturated / -mercapto ester (65) forms complexes with Cu1, Ni11, Co111 and Fe111.190,258 The Niu complex of (66) has also been reported.190 These complexes are stabilized by electron delocalization in the chelate ring, which is identical with that of monothio-/ -diketones. 

Benzohydroxamic acid dioxouranium complexes, 507 metal complexes, 506, 507 as metal precipitant, 506 Benzohydroxamic acid, iV-methyl-metal complexes, 506 Benzohydroxamic acid, N-phenyl-metal complexes, 507 reactions with carboxylic acids, 507 as metal precipitant, 506 titanium complexes, 506 Benzohydroxamic acid, A -(o-tolyl)-as metal precipitant, 506 Benzohydroxamic acid, N-wi-tolyl-p-methoxy-metal complexes, 506 Benzoic acid, dihydroxy-beryllium(II) complexes, 481 Benzoic acid, o-mercapto-esters... 

As an example, both monofunctional and multifunctional polymeric mercapto-esters were deposited onto optically smooth silicon wafers coated with vapor-deposited copper. The copper had been oxidized to Cu20, as verified by XPS. Infrared reflectance (RAIRS) at 81° (4 cm-1 resolution, 2000 scans) using an MCT detector yielded information on both the nature and the durability of the mercaptoester bond to the metal oxide film. A 16 cm l shift (1740— 1724 cm-1) was observed in the carbonyl absorption of stearyl thioglycolate (STG) deposited onto the Cu20 mirror. The absorption spectrum of the carbonyl region is illustrated in Fig. 11, both for the pure STG and the reacted monolayer. 

An account has also been given of the reaction between benzylmercaptan and cis-benzene trioxide.With a-mercapto esters, p-substituted phenyloxiranes undergo normal opening, without being affected by the substituents on the benzene ring. Chalcone oxides react with mercaptan with accompanying C-C bond cleavage (Eq. 308). ... 

Purified mercaptoacetic acid is sold in anhydrous or 85% aqueous forms, most often for subsequent conversion to the esters or to the ammonium, sodium, potassium, or calcium salts. 3-Mercaptopropionic acid is produced from metal hydro sulfides and either acrylic acid or acrylonitrile. Mercaptoethyl tallate is another mercapto-ester used in commercial organotin stabilizers. It is manufactured by a standard esterification of mercaptoethanol and tall oil, a mixture of fatty acids. 

Reaction of compound 8 with a-halo nitriles (R CHHalCN) gave the 3-amino compounds 7 after cyclization of the intermediate S-alkylated products 12 with aqueous potassium hydroxide. Similarly reaction of 2-amino-3-chloropyrazine (13) with the mercapto esters 14 in the presence of sodium ethoxide gave the 3-oxo derivatives 16 on refluxing in dioxan. The intermediates 15 are involved in the reaction. The most convenient synthesis of these compounds involves reaction of 2-amino-3-chloropyrazines with thioglycollic acid in alkali and acid-catalyzed cyclization of the carboxymethylthio derivative. ... 

Conversions of aldehydes and ketones into thiirans have been reported, using the cr-anions of alkyl thiolbenzoates (5), the dianions of a-mercapto-esters, and, in... 

Highly substituted tetrahydrothiophens can also be prepared by two related routes, the first of which involves the Michael addition of mercapto-esters to benzylidene-benzoylacetonitriles in the presence of triethylamine/ The authors had expected the formation of a 3-oxotetrahydrothiophen by a Dieck-mann-type cyclization. In the second reaction the base-catalysed condensation of diketosulphides with 1,2-diketones led smoothly to tetrahydrothiophen diols rather than the expected thiophens." In both cases the products are probably resistant to dehydration due to steric crowding. 

The interaction of a-mercapto-esters with ethyl cyanoacetate or analogous nitriles incorporating active methylene groups yields 2-carboxymethylene-4-thiazolidinones (222). They are visualized to arise by the attack of the sulphur at the nitrile carbon, followed by lactam formation. ... 

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