Thiol structure

Chong, S., Fung, H-L., Biochemical and pharmacological interactions between nitroglycerin and thiols. Effects of thiol structure on nitric oxide generation and tolerance reversal. Biochem. Pharmacol. 42 (1993), p. 1433-1439... 

The rates depend on the thiol structure, and correlate well with inductive effects. Thus, the -NH2 and COO groups destabilize and stabilize the red adduct, respectively. When the groups are blocked by acetylation or esterification, their influence is suppressed, as shown by IV-acetylcysteine, which forms the most stable adduct in the series because of the unprotected COO and the acetylated amino group. 

The electrochemical process at the modified electrode can thus be separated into two steps. First is a chemical reaction between PQQ and thiol to produce the reduced form of PQQ, PQQFE. This is followed by electrochemical oxidation of PQQFE to produce PQQ, which completes the cycle. We observed an oxidation potential of PQQEI2 much lower than the 0.5 V vs Ag/AgCl reported earlier for the detection of endo- and exogenous thiols such as cysteine and glutathione17. This difference could be due to changes in the procedure (smaller amount of pyrrole used) as well as different thiol structures. 

A thione-thiol structure in the crystalline state and in aprotic solvents was established for the [l,2,4]triazolo[3,4- >][l,3,4]thiadiazole (37), in accordance with calculations of the 7r-bonding and solvation energies by the Pariser-Parr-Pople (PPP) method and also on the basis of IR and UV spectral information (75CHE304). The electron-density distribution in four tautomeric forms, calculated by the PPP method, also indicates that the ring-junction carbon atom is the most reactive one with respect to nucleophilic attack (75CHE500). 

The thiols themselves are best made by the lithiation sulfur method, followed by acidification.198-199 IR and NMR studies show that furan-2-thiols and furan-3-thiols are tautomeric but that the thiol, not the thione, is always by far the major isomer. This differs from the oxygen analogs. Evidence from the ionization potentials supports the thiol structure. Furylthioethers have IP values about 0.3 eV higher than do the parent thiols, just as in the benzene series.199... 

H2l-thioglycolate suggest that the dependence on thiol structure may be due to internal quenching of one radical site of the activated chromophore by the hydrogen atoms of the thiol side chain. A comparison of DNA damage produced by activation of the neocarzinostatin chromophore with several thiol activators revealed that the fragmentation pathway (i.e. the initial site... 

Simple thiols Structural class 1 Ethanethiol 1659 75-08-1 No Yes. The NOEL of 0.56 mg/kg bw perday See note 8 No safety... 

Epithlo-c/s-p-menthane Simple thiols Structural class 1 1685 N No safety concern... 

Figure 2. Effects of temperature and thiol structure on the oxygen uptake in HMPA (hexamethylphosphoramide). O 1-C4H,SH in KOH/HMPA (23-5°) A QHgSH in KOH/HMPA (23-5°) 1-Ci.HsjSH in KOH/HMPA (23-5°) O l-Ci HjjSH in KOH/HMPA (80°). Reproduced by permission of author and editor from Tetrahedron, 21, 2271 (1965).

Damodaran, V.B., et al. 2012. S-Nitrosated biodegradable polymers for biomedical applications synthesis, characterization and impact of thiol structure on the physicochemical properties. Journal of Materials Chemistry 22(13) 5990-6001. 

Thiono-5-mercapto-l,3,4-thiadiazoline, the thiono-thiol structure of which is supported by its i.r. and u.v. spectra, forms a 1 1 molar complex with mercurous ion. The dissociation constant of this adduct has been determined spectrophotometrically (Jc — 1 x 10" at 20 °C) by the method of Job. ... 

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