Thiols, redox reactions

Nitro- and nitroso-compounds,170171 amines, and thiols induce the decomposition of diacyl peroxides in what may be written as an overall redox reaction. Certain monomers have been reported to cause induced decomposition of BPO. These include AN,172 A -vinylcarbazole,17,177 Ar-vinylimidazole178 and NVP.177... 

CODH/ACS is an extremely oxygen-sensitive protein that has been found in anaerobic microbes. It also is one of the three known nickel iron-sulfur proteins. Some authors would consider that there are only two, since the CODH and ACS activities are tightly linked in many organisms. However, there is strong evidence that the ACS and CODH activities are associated with different protein subunits and the reactions that the two enzymes catalyze are quite different. CODH catalyzes a redox reaction and ACS catalyzes the nonredox condensation of a methyl group, a carbonyl group, and an organic thiol (coenzyme A). 

The use of tetraoctylammonium salt as phase transfer reagent has been introduced by Brust [199] for the preparation of gold colloids in the size domain of 1-3 nm. This one-step method consists of a two-phase reduction coupled with ion extraction and self-assembly using mono-layers of alkane thiols. The two-phase redox reaction controls the growth of the metallic nuclei via the simultaneous attachment of self-assembled thiol monolayers on the growing clusters. The overall reaction is summarized in Equation (5). 

Equilibrium considerations other than those of binding are those of oxidation/reduction potentials to which we drew attention in Section 1.14 considering the elements in the sea. Inside cells certain oxidation/reductions also equilibrate rapidly, especially those of transition metal ions with thiols and -S-S- bonds, while most non-metal oxidation/reduction changes between C/H/N/O compounds are slow and kinetically controlled (see Chapter 2). In the case of fast redox reactions oxidation/reduction potentials are fixed constants. 

Figure 1.10 Sulfhydryl groups may undergo a number of additional reactions, including acylation and alkylation. Thiols also may participate in redox reactions, which generate reversible disulfide linkages.

The reaction of nitrosoarenes with alkanethiols may provide a new and simple synthetic route to iV-aryl-S-alkylsullinarnidcs which has not been mentioned hitherto62. Nitrosoarenes are frequently accessible by simple redox reactions of the commercially available arylamines or nitroarenes2,71. High yields of the desired sulfinamide may be achieved by adjusting stoichiometry, pH and solvent polarity. With aryl thiols, however, this method may not be applicable because of the very sluggish reaction (see Table 2). Whether such a synthetic route can be extended to alkylnitroso compounds remains to be established. 

Organochalcogen(II) compounds, 100-102 Organochalcogen(IV) compounds, 100-102 Organoselenium compounds dehalogenation reactions, 96 electrochemical reduction, 113-117 haloperoxidase-like activity, 108-113 with odd number of ligands, 100-102 one-electron oxidation, 117-118 oxidation of thiols, 102-106 redox reactions, 79-80 thioperoxidase-like activity, 108-113 Organotellurium compounds... 

Clearly, this thiol can be used to attach ferrocene groups (Fc) to the Au electrode surface. If we abbreviate the surface-confined ferrocene group as -Fc, it should be possible to drive the following surface redox reaction ... 

Alcohols and thiols also react rapidly with most amides to give alkoxide or thiolate ligands with liberation of amine. Steric factors can be sufficiently important to limit this exchange (e.g. equation 66) and in some instances redox reactions may occur (equation 67).212 Salt formation is also possible in some cases (equation 68).213... 

More recently, chemiluminescence detectors based on redox reactions have made possible the detection of many classes of compounds not detected by flame ionization. In the redox chemiluminescence detector (RCD), the effluent from the column is mixed with nitrogen dioxide and passed across a catalyst containing elemental gold at 200-400°C. Responsive compounds reduce the nitrogen dioxide to nitric oxide. The nitric oxide is reacted with ozone to give the chemiluminescent emission. The RCD yields a response from compounds capable of undergoing dehydrogenation or oxidation and produces sensitive emissions from alcohols, aldehydes, ketones, acids, amines, olifins, aromatic compounds, sulfides, and thiols. 

Co catalysts are used to catalyze a series of oxidations that involve one-electron redox reactions, such as oxidation of phenolic compounds, thiol oxidation, and oxyfunctionalization of saturated hydrocarbon groups. 

In conclusion, the [NiS] mediated formation of thioesters from alkyl, CO, and thiol groups lends support to an acetyl-CoA formation pathway that comprises CO insertion into a Ni Me and an intramolecular S -C bond formation between nickel-bound acyl groups and thiolate ligands. These reactions are favored at square-planar nickel complexes that enable two-electron redox reactions and readily add fifth ligands. 

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