Thiolic —

In aqueous solutions at pH 7, there is little evidence of complex formation between [MesSnflV)] and Gly. Potentiometric determination of the formation constants for L-Cys, DL-Ala, and L-His with the same cation indicates that L-Cys binds more strongly than other two amino acids (pKi ca. 10,6, or 5, respectively). Equilibrium and spectroscopic studies on L-Cys and its derivatives (S-methyl-cystein (S-Me-Cys), N-Ac-Cys) and the [Et2Sn(IV)] system showed that these ligands coordinate the metal ion via carboxylic O and the thiolic 5 donor atoms in acidic media. In the case of S-Me-Cys, the formation of a protonated complex MLH was also detected, due to the stabilizing effect of additional thioether coordination. ... 

In the context of studies on the coordination of organotin(IV) moieties by thiolic S and heterocyclic N atoms, diorganotin(IV) complexes of 2-mercapto-pyridine, R2Sn(SPy)2 and R2SnCl(SPy), have been characterized in the solid state and in solution. The structure of the latter complex (R = Ph) was determined by XRD (Figure 17). The crystal is monoclinic in the space... 

There are other synthetic and natural thiolic compounds possessing antioxidant activity. One such compound is tetradecylthioacetic acid (TTA), which inhibited the iron-ascorbate-induced microsomal lipid peroxidation [234]. Its Se analog exhibited even a more profound antioxidative effect. 

Similar to some other antioxidants, pyrrolopyrimidines do not contain active free radical scavenging groups such as phenolic or thiolic substituents. At present, at least two different mechanisms of their antioxidant activity have been proposed [307], It was suggested that pyrrolopyrimidines, which are electron donating compounds, can be oxidized by hydroxyl or peroxyl radicals or hydroxylated by cytochrome P-450 forming phenolic metabolite... 

The coordination atmosphere of the metal ion in solution can also be expected to affect the reaction rate. Microanalytical results indicate that the active catalysts in cobalt and nickel systems could well be metal thiolic species produced in situ. However, these complexes are appreciably more soluble in the, alkaline solutions than are metal hydroxides (see, for example, the analysis results reported in Table IV), and it is not possible on the present evidence to differentiate between catalysis as a result of increased solubility (comparing metal hydroxides and metal thiolic complexes), and catalysis as a result of differences in the allowed ease of electron transfer. It is apparent, however, that most of the metals investigated (Table I) are poor catalysts because they form only the insoluble hydroxide complexes. 

Fig. 120. Addition of organometals to thiolic or phenolic Mannich bases.

Finally, certain types of Mannich bases may behave as auxiliaries in the erosslinking process. In particular, the thiolic bases 433 are employed as vulcanization accelerators in the production of tires. ""... 

The distribution of the organic sulfur functional groups was determined in five coals and treated coals using thermo-kinetic analysis. The data surest that 15-30% of the organic sulfur is sulfidic in all coals. About 30-40% of the organic sulfur in lignite is thiolic and the rest is thiophenic. 

The majority of the organic sulfur in high-ranked coals (i.e., LVB) is thiophenic, while in low-ranked coals (i.e., lignites) most of the organic sulfur is thiolic or sulfidic. 

Coals with a large content of organic sulfur can be divided into two groups coals that can be partially desulfurized and coals that cannot be desulfurized easily. The portion of the organic sulfur that can be desulfurized is that present in the form of thiolic groups and aliphatic sulfides. 

All the polymers contained some thiolic sulfur. The results of the tests are summarized in Table I, which shows the temperature at which the apex corresponding to each functional group appears. 

Coal S Accounted Thiolic Thiophenolic Sulfide Sulfide Thiophenes ... 

However, preliminary data show that part of the organic sulfur can be desulfurized easily. In particular, the thiolic sulfur and part of the sulfidic sulfur can be desulfurized easily. Therefore, the authors suggest that coals with excess organic sulfur be divided into two groups coals that can be desulfurized easily, in which most of their organic sulfur is thiolic, and coals that cannot be desulfurized easily, in which most sulfur is nonthiolic. Thus thermokinetic tests can be used to screen coals and to determine the process in which they can be utilized. 

Reversed-phase HPLC with fluorescence detection, after derivatization of plasma thiols with ammonium 7-fluorobenzo-2-oxa-l,3-diazole-4-sulphonate (SBD-F), is the most widely used method to determine total plasma amino thiols (cysteine, cysteinylglycine, and homocysteine). The time required for sample preparation (thiolic reduction, deproteinization, and precolumn derivatization g with SBD-F) and for thiol derivatives separation is nearly 2 h per sample. =... 

The 1,3-cyclohexadiene could not be prepared with higher purity than 98% and hence the analysis based on the final products is less meaningful. The yield of 3- and 4-hydroxycyclohexenes show that only 31% (0.18 pmolJ /0.58 pmolJ ) of the OH radicals add to the double bonds. There is no information about the missing 44% (100% — 25%—31%). Von Sonntag and coworkers suggested that the yield of hydroxy cyclohexenes is not indicative of the OH addition to the double bonds due to non-quantitative reaction of the ally lie radical 1 (equation 10) with RSH. Since, in the case of 1,4-cyclohexadiene, they found complete material balance, they concluded that the alky lie radical formed in reaction reacts quantitatively with the thiolic compound. Thus, radical 2 formed in reaction (11) will react quantitatively with RSH. The inefficiency of the reduction of the allylic radical by the thiol is probably due to the weak ally lie C—H bond which leads to a six orders of magnitude lower rate constant for the RSH-I- allylic radical reaction compared with the RSH-I- alkyl radical reaction. If all the material imbalance is due to incomplete reduction of the allylic radical, its formation is the main path of reaction of OH with 1,3-cyclohexadiene. 

Thiolic acid A compound of the general type RC(=0)SH. See also thionic acid. 

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