3, 5-dimercapto properties

Chemical Properties. The most significant chemical property of L-ascorbic acid is its reversible oxidation to dehydro-L-ascorbic acid. Dehydro-L-ascorbic acid has been prepared by uv irradiation and by oxidation with air and charcoal, halogens, ferric chloride, hydrogen peroxide, 2,6-dichlorophenolindophenol, neutral potassium permanganate, selenium oxide, and many other compounds. Dehydro-L-ascorbic acid has been reduced to L-ascorbic acid by hydrogen iodide, hydrogen sulfide, 1,4-dithiothreitol (l,4-dimercapto-2,3-butanediol), and the like (33). 

Although the first all-sulfur macrocycles were prepared many years ago " the first systematic study of such compounds was initiated by Busch and his coworkers , who were interested in the cation binding properties of such ligands. A sequential synthesis was utilized to produce 1,4,8,11-tetrathiacyclotetradecane [tetrathia-14-crown-4 (70)] . In the first step, 1,3-propanedithiol is metallated using sodium and alkylated with 2-chloroethanol. The diol was then treated with thiourea to form the dimercapto-dithioether compound 9. The latter was once again metallated with sodium and allowed to react with 1,3-dibromopropane. The yield of 70 in the ring closure step, conducted at high dilution in absolute ethanol, was 7.5% after recrystallization. The entire sequence is illustrated in Eq. (6.8) . ... 

Tungsten, tris(2,3-dimercapto-2-butenedinitrile)-structure, 1,63 Tungsten alkoxides physical properties, 2,346 synthesis, 2,339... 

Sulfur-containing compounds have been shown in vitro to interact with tributyltin compounds to produce other compounds with lower hemolytic activity (Byington et al. 1974). It has also been shown in vitro that the toxic properties of dibutyltin dichloride may be enhanced by meso, 2-3,-dimercapto-succinic acid, by means of a hydrophobic reaction with glutathione enzymes (Henninghausen and Merkord 1985). Such interactions could be of importance in treatment of organotin poisonings. 

I. Synthesis and chiroptical properties of poly(Y-ketosulfide)s derived from (-) (2R,3R)-l,4-dimercapto-2,3-butanediol, Mcikromol. Chem., 193, 2883, 1992. 

II. Synthesis and chiroptical properties of poly(y-kctosulfide)s containing the (2R,3R)-1,4-dimercapto-2,3-butanediolbutyral-dehydeacctal moiety. Polymer,, 34, 3778, 1993. 

Due to the electron attraction of the ring, the NH groups in amido-thiadiazoles and thiadiazolylhydrazones (54) have weakly acidic character. Potential mercapto compounds have distinctly acidic properties, and 2,5-dimercapto-l,3,4-thiadiazole and its 4-sub-stituted derivatives are strong acids. The pK and some pKn values of these compounds are found in Table III. 

The properties of mercapto-l,2,4-thiadiazoles, particularly those of the interesting 3,5-dimercapto compound (perthiocyanic add) have been established in fair detail for some time3 recent work has in the main been supplementary in nature. Attention is drawn to the extensive use of 5-mercapto-l,2,4-thiadiazoles in the production of cephalosporin derivatives this is briefly reviewed separately at the end of this Section. 

Bis(dithio)thiadiazoles (e.g., 524)113,515 and bis(thiosulfenamides)516 are employed as corrosion inhibitors in lubricants. The antiwear and extreme-pressure properties of lubricating greases are improved by the addition of (polymeric) 3,5-dimercapto-l,2,4-thiadiazole,517 2,4-dialky 1-1,2,4-thiadiazo-... 

The intercalation of cobaltocene and its ions into a range of materials have been considered e.g. into Cd2P2S6. Cobaltocenium salts have been used as redox labels in Nation films. The photochemical properties of metallocene redox diodes has been reported. Several electrochemical investigations have been carried out on cobaltocenes or cobaltocene modified electrodes. Rigid rod paraphenylene acetylenes have been introduced into metallocenes for non linear optic use. The crystal structure of cobaltocene has been redetermined " and the crystal structure of cobaltocenium bis[(4,5-dimercapto-S4,S5)-l,3-dithiolate-2-thionato] nickelate has been reported. Finally, cobaltocenium metallacarboranide mixed-sandwich salts have been prepared. ... 

The emphasis here is on the properties of glutathione (or cysteine if data for cysteine, but not GSH are available). Dithiols which form cyclic or stabilized disulphide radical anions, such as dithiothreitol (//ireo-l,4-dimercapto-2,3-butanediol) [29-33], or the reduced form of lipoic acid (6,8-dithiooctanoic acid) [15, 34-37], in effect have uncharacteristically high values of to be good models for glutathione. In addition, biological effects may be complicated by thiol/disulphide exchange since these thiols will reduce many disulphides [38-40]. Arenethiyl radicals (e.g. phenylthiyl or derived from 2-mercaptoimidi-azole) are closer to phenoxyl radicals in nature than aliphatic thiyl radicals [41-44]. 

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