Zinc dialkyldithiocarbamates

Peroxide decomposers—These function by reacting with the initiating peroxides to form nonradical products. Presumably mercaptans, thiophenols, and other organic sulfin compounds function in this way [19]. It has been suggested that zinc dialkyldithiocarbamates function as peroxide decomposers, thus giving mbber compounds good initial oxidative stability. 

Complexes of zinc dialkyldithiocarbamates with bidentate nitrogen ligands such as 1,10-phen-anthroline have been structurally characterized.563 The related complexes (4,4 -bipyridyl)... 

The authors describe experiments on six NR compounds commonly used for latex gloves to determine the potential hazards of skin contact with reference to curing compounds and accelerators, including mercaptobenzthiazole and zinc dialkyldithiocarbamates. Simulation methods and the influence of a common hand disinfectant were investigated. In the case of tetramethylthiuram disulphide, it was discovered that decomposition products could be formed on the skin which are not present in the original rubber. 6 refs. Articles from this journal can be requested for translation by subscribers to the Rapra produced International Polymer Science and Technology. Accession no.849747... 

The second important class of accelerators are zinc dialkyldithiocarbamates (XXI). These are more active with faster vulcanization rates than the 2-mercaptobenzothiazole sulfena-mides. Also, activators are not usually needed since the zinc is incorporated into the accelerator molecule. Tetralkylthiuram disulfides (XXII) in combination with activators S... 

Inhibition of Oxidation. Several antioxidants were tested in chloroprene at 45°C. Those which can be classified as mainly suppressors of initiation (I), because of their ability to destroy hydroperoxides—namely, zinc dialkyldithiophosphates, zince dialkyldithiocarbamates, triphenyl-phosphine, and the like—had no inhibiting effect at the 100-p.p.m. level. 

This exchange leads first to the formation of the mixed products and, in the second step, full ligand exchange takes place to produce molybdenum dialkyldithiophosphate (Mo(ddp)2) and zinc dialkyldithiocarbamate (Zn(dtc)2). The equilibrium in this reaction favors Mo(dtc)2 and Zn(ddp)2 formation, and the... 

Synthesis The synthesis of zinc dialkyldithiocarbamates is as in Reaction sequence (4.53) [64] ... 

Ihe efficiency of crosslinking is increased by including accelerators (e.g., tetraalkylthiuram disulfide, zinc dialkyldithiocarbamate) and activators (e.g., ZnO plus stearic acid) which inhibit the formation of long polysulfide crosslinks, vicinal crosslinks and intramolecular cyclic sulfide structures. 1,4-Poly-l,3-dienes are also crosslinked by heating with -nitrosobenzene, phenolic resins or maleimides for applications requiring improved thermal stability. 

Zinc dithiocarbamates have been used for many years as antioxidants/antiabrasives in motor oils and as vulcanization accelerators in rubber. The crystal structure of bis[A, A-di- -propyldithio-carbamato]zinc shows identical coordination of the two zinc atoms by five sulfur donors in a trigonal-bipyramidal environment with a zinc-zinc distance of 3.786 A.5 5 The electrochemistry of a range of dialkylthiocarbamate zinc complexes was studied at platinum and mercury electrodes. An exchange reaction was observed with mercury of the electrode.556 Different structural types have been identified by variation of the nitrogen donor in the pyridine and N,N,N, N -tetra-methylenediamine adducts of bis[7V,7V-di- .vo-propyldithiocarbamato]zinc. The pyridine shows a 1 1 complex and the TMEDA gives an unusual bridging coordination mode.557 The anionic complexes of zinc tris( V, V-dialkyldithiocarbamates) can be synthesized and have been spectroscopically characterized.558... 

Considerable progress has been made in studying tribofilms in the last decade. A number of important surface and thin film techniques have been developed in recent years, which are contributing to a better understanding of at least some tribochemical processes of boundary lubrication. In recent years, X-ray absorption near edge structure XANES spectroscopy, a powerful technique for tribofilm characterization, was used to identify a layered structure (surface and bulk) of tribofilms. The chemistry of tribofilms generated by the combination of zinc dialkyldithiophosphate (ZDDP) and molybdenum dialkyldithiocarbamate (MoDTC) has been examined. 

Solvated Forms of Adducts of Dialkyldithiocarbamate Zinc(ll) Complexes 311... 

Table 4 C and N chemical shifts (ppm) of adducts (28-33) of dialkyldithiocarbamate zinc(II) complexes with cyclic N-donor bases [relative to TMS ( O and NH4CI (>= N)]... 

Poly(vinyl halides) - The photocatalysed oxidation of PVC has been undertaken in the presence of titanium dioxide and zinc oxide pigments and the extent of dehydrochlorination measured. Acetic and formic acids were major products along with carbon dioxide. Copper(II) dialkyldithiocarbamate complexes are also sensitisers. Photodegradable PVC has also been developed by grafting with benzophenone chromophores. Plasticised PVC also degrades and discolours on irradiation but this is due mainly to the plasticiser. ... 

The ajkyl and dialkyldithiocarbamates are important commercially. Some of their heavy metal salts, produced by metathesis from the sodium or ammonium salt solution, are used as accelerators for the vulcanization of rubber (e.g., the zinc salt). 

Single-crystal X-ray studies of the butoxy and octyloxy homologs showed that these crystalline materials were in fact dimers (Figure 88) containing an eight-membered ring. Such structures had been observed previously in dialkyldithiocarbamates of zinc(ll), although the unsubstituted dithiobenzoate of zinc(II) was, in fact, monomeric. " ... 

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