Reduction dithiocarbonate

Numerous research activities have focused on the improvement of the protective films and the suppression of solvent cointercalation. Beside ethylene carbonate, significant improvements have been achieved with other film-forming electrolyte components such as C02 [156, 169-177], N20 [170, 177], S02 [155, 169, 177-179], S/ [170, 177, 180, 181], ethyl propyl carbonate [182], ethyl methyl carbonate [183, 184], and other asymmetric alkyl methyl carbonates [185], vinylpropylene carbonate [186], ethylene sulfite [187], S,S-dialkyl dithiocarbonates [188], vinylene carbonate [189], and chloroethylene carbonate [190-194] (which evolves C02 during reduction [195]). In many cases the suppression of solvent co-intercalation is due to the fact that the electrolyte components form effective SEI films already at potential which are positive relative to the potentials of solvent co-intercalation. An excess of DMC or DEC in the electrolyte inhibits PC co-intercalation into graphite, too [183]. 

Sugar allylstannanes have been prepared by the homolytic reduction of allylic dithiocarbonates,255 and by the reaction of Bu3SnCu with an allylic mesylate or bromide 256 257 the relative yields of isomers depend on the steric demands of the sugars (Equations (90) and (91)). 

An unusual reaction of methoxythiocarbonyl chloride with tetra-n-butylammo-nium iodide in the presence of sodium thiosulphate leads to the formation of 0,5-dimethyl dithiocarbonate [49], The reaction appears to involve a reduction step, with the iodide anion being regenerated from the released iodine by the thiosulphate ions (Scheme 4.7). In the absence of the thiosulphate ions, the thiocarbonyl chloride decomposes to yield chloromethane and carbonyl sulphide. 

Reaction of norbornane trithiolane (24) with both dichloro- and dibromocarbene afforded the trithiocarbonate (94), which upon further reaction with the dihalocarbene yielded the corresponding dithiocarbonate <90JOC1146>. The mechanism of formation of (94) from (24) is postulated to proceed by addition of the carbene to S-2 of the trithiolane, followed by a ring-expansion reduction sequence as outlined in Scheme 22. 

Liver is the principal site of chloroform metabolism which involves two major pathways, both of which are catalyzed by the cytochrome P-450 enzymes in the presence of NADPH. The oxidative pathway produces phosgene and the reductive pathway produces the dichloromethyl free radical. Other metabolites of chloroform include chloro-methanol, hydrochloric acid, hydrogen chloride, and digluathionyl dithiocarbonate, with carbon dioxide as the predominant end product of metabolism. 

Another method for photodegrading polyethylene is to include metal salts, which catalyze photooxidation reactions, in the solid polymer. The compounds most generally used for that purpose are divalent transition-metal salts of higher aliphatic acids, such as stearic acid or dithiocarbonates or acetoacetic acid. The photochemical reaction is an oxidation-reduction reaction that forms free radicals capable of reacting with polyethylene, RH, to initiate an autooxidation chain reaction, as follows ... 

Lanosteryl S-methyl dithiocarbonate in xylene added during 0.5 hr. under argon to a stirred and refluxing mixture of tributylstannane and xylene, and refluxing continued 2 hrs. -> lanosta-8,24-diene. Y 83%. - This reduction is part of a method for the deoxygenation of sec. alcohols. F. e. and related reactions s. D. H. R. Barton and S. W. McCombie, Soc. Perkin I 1975, 1574. 

Vicinal diols react with CS2 under basic conditions, to give the corresponding bis-dithiocarbonates. Reduction with tributyltin hydride in toluene gives high yields of the alkenes. 

Additionally, the reduction process of Barton and McCombie has been developed into a useful technology. The Barton-McCombie procedure (Scheme 8.22) involves the conversion of an alcohol to a thiocarbonate (or dithiocarbonate) derivative (usually in two steps) and the reaction of the latter with tributyltin hydride and azobisisobutyronitrile (AIBN) (bis(l-cyano-l-methylethyl)diazine, [(CH3)2C(CN)N=NC(CN)C(CH3)2]). As shown in Scheme 8.22, decomposition of AIBN produces a radical, which, in turn, abstracts hydrogen from tributyltin hydride, generating the tributyltin radical. The reaction of the latter with sulfur and the subsequent decomposition of that intermediate produces a deoxygenated. 

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