Sulfur Linkages

Semi-EV cures represent a compromise between conventional and EV cures. Although semi-EV cures do yield polysulftde cross-links, they tend to minimize formation of kiefficient moieties such as sulfur bridging with itself, accelerator-terminated sulfur linkages, etc. This cleaner usage of sulfur is the reason for thek compromise properties between conventional and EV cures. 

Kimura, T. Biochemical Aspects of Iron Sulfur Linkage in None-Heme Iron Protein, with Special Reference to Adrenodoxin . Vol. 5, pp. 1-40. 

Polyurethane ionomers, 25 460 Polyurethane-modified isocyanurate (PUIR) foams, 25 455, 456 Polyurethanes (PUs), 9 564. See also Polyurethane (PU) antioxidant applications, 3 121-122 cardiovascular device applications, 3 720 CASE, 25 474-477 commercial block copolymers, 7 648t containing sulfur linkages, 23 742-745 dyeing, 9 204... 

Sulfuric acid stack emission limit, 23 774 Sulfuric acid storage tanks, 23 783 Sulfur impregnation, 23 593-594 Sulfur-iodine (S-I) cycle, 73 848 Sulfurized olefins, 23 642 Sulfur ligands, platinum, 79 656 Sulfur linkages... 

If a large number of branches exist that connect all of the backbone molecules into a three-dimensional network, the material will not flow when heated, and it is considered a thermoset resin. Vulcanized rubber is an example where the sulfur linkages create a three-dimensional network, converting the precursor rubber into a solid thermoset material. Crosslinked backbone chains are shown in Fig. 2.8(e). When extruding many thermoplastics, the polymer can undergo chemical reactions to form small amounts of crosslinked material. Partial crosslinking is a problem with some PE resins that contain residual double bonds that are made using... 

Recently, palladium-catalyzed carbonylation of chloropyrimido[4,5-d]pyrimidines has been reported (Equation 51) <2006W0065703>. Raney nickel-mediated desulfurization of alkylthiopyrimido[4,5-, pyrimidines was described in GHEC(1984), and has been applied recently both in the desulfurization of reduced species (Equation 52) <2001WO64679> and for cleavage of sulfur linkages in traceless solid-phase synthesis <1999BMCL965,... 

The hydrolyses of l-imino-l,2-thiazetidin-3-ones, which are themselves the result of addition of ketenes to sulfur diimides, are usually characterized by loss of the imino sulfur linkage (Scheme 24) (69TL447,70TL1427). However, one account where the iminothiazetidine... 

Solid state NMR Stable sulfur linkages between the aromatic units are formed... 

Both compounds (Figure 4.7) are non-competitive inhibitors of chitin synthase and also interfere with the Bremner-Greenberg methylation pathway.6 Their activity is dependent upon the oxidation of the phosphorous - sulfur linkage, a feature that is the basis of resistance development, which is common sensitive strains of P. oryzae metabolise the compounds more rapidly than resistant strains. 

Our early work examined the reaction of PCTFE with sulfur, selenium and phosphorous nucleophiles 9 to achieve high levels of functionalization through a well-precedented (in the case of perfluoroalkyl iodides)20"24 one electron transfer, radical anion chain process. While such a reaction demonstrated the feasibility of using one-electron processes for the functionalization of PCTFE, the carbon-sulfur linkage remained susceptable to oxidation. 

The configuration of bovine serum albumin isolated from milk has not been investigated, but extensive investigations of this protein isolated from bovine blood serum have been made. The protein exhibits at least three different kinds of heterogeneity (1) due to polymer formation, (2) related to the sulfur linkages in the molecule, and (3) microheterogeneity. Fractionation of bovine serum albumin on DEAE-Sephadex A-50 resulted in a monomer and two dimer fractions (Janatova et al. 1968),... 

B 4. Bateman, L., R. W. Glazebrook, C. G. Moore, R. W. Saville Structural characteristics of the sulfur linkage in natural-rubber vulcanizates. Proc. 3rd Rubber Technol. Conf. London 298 (1954, pnbl. 1956). 

The critical step in the use of multiple sulfur linkages is the availability of HS" from the reduced enzyme system. The HS" could possibly attack the cyclic or the acyclic multiple sulfur linkages through a nucleophilic mechanism. The cleaved sulfide linkages undergo oxidation to sulfite or thiosulfate. This seems a plausible pathway for the oxidation of the sulfur compounds in the present study. 

Benzopentathiepin 27 reacts with phosphorus ylides d-RCgPLtCP PPhjCl (R = MeO, Me, H, Cl, NO2) to form a mixture of benzotetrathiepins 28 and benzotrithiins 29 (Equation 3). The carbanion fragment of the phosphorus ylides replaced the one or two sulfur atoms in the multi-sulfur linkages of benzopentathiepin. Systematic desulfurization to form a new cyclic system was accomplished by the use of a combination of phosphorus ylide and triphenylphosphine in the reactions of benzopentathiepin, benzotetrathiepins, and benzotrithiins <1997H(44)187>. 

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