TETRAETHYLTHIURAM

Sulfur-containing chemicals such as dimorpholinyl disulfide (DTDM) and tetraethylthiuram disulfide (TMTD) are not only effective accelerators, but they can also be used as sulfur donors. As such, they are effective ia controlling sulfur cross-link length to form primarily moao- and disulfide cross-links. These short cross-links are more thermally stable than conventional sulfur curing and thereby provide better heat and set resistance. 

The initial sulfur copolymer that is formed is often high conversion and gelled. Molecular weight is reduced to the required level by cleaving some of the polysulfide Linkages, usually with tetraethylthiuram disulfide. An alkaU metal or ammonium salt (30) of the dithiocarbamate, an alkaU metal salt of mercaptobensothiasole (31), and a secondary amine (32) have all been used as catalysts. The peptization reaction results in reactive chain ends. Polymer peptized with diphenyl tetrasulfide was reported to have improved viscosity stabiUty (33). 

Monomer conversion (79) is followed by measuring the specific gravity of the emulsion. The polymerization is stopped at 91% conversion (sp gr 1.069) by adding a xylene solution of tetraethylthiuram disulfide. The emulsion is cooled to 20°C and aged at this temperature for about 8 hours to peptize the polymer. During this process, the disulfide reacts with and cleaves polysulfide chain segments. Thiuram disulfide also serves to retard formation of gel polymer in the finished dry product. After aging, the alkaline latex is acidified to pH 5.5—5.8 with 10% acetic acid. This effectively stops the peptization reaction and neutralizes the rosin soap (80). 

The 8-coordinate species [Mo(Et2dtc)4] can be obtained by reaction of Mo(CO)e with tetraethylthiuram disulfide (1 2) in acetone under N2. The X-ray structure revealed square-antiprismatic coordination, with a crystallographic, twofold axis coinciding with the molecular pseudo 4 axis (158). The magnetism and spectra of [M(dtc)4]"" (M = Mo or W n = 0 or 1) have been interpreted in terms of dodecahedral symmetry (159). 

Although ultra accelerators or sulfur donors can be used together with primary accelerator (such as sulfenamide, TBBS) to improve cure rate as well as the heat resistance [16-18], their use is restricted because of the associated nitrosamine issue [19]. Accelerators derived from secondary amines, for example, MBS, TMTD, TETD, TMTM, and OTOS fall into this category. The combination of sulfenamide, such as CBS or TBBS, and a thiuram, such as TMTD or TETD, shows high-cure rates but suffers from the adverse effects on scorch resistance and vulcanizate dynamic property [20]. Additionally as previously mentioned, the use of TMTD or Tetraethylthiuram disulhde (TETD) or A-oxidiethylene dithiocarbamyl-A -oxidiethylene sulfenamide (OTOS) or 4,4 -Dithiodimorpholine (DTDM) is undesirable [21] due to concerns over carcinogenic nature of the A-nitrosamines formed from the parent amines. The solution to this originated by introduction of nitrosamine safe ultra accelerator such as TBzTD [22,23]. 

In particular, the oxidation with tetraethylthiuram disulfide is interesting, as it yields the compound [Mo(Et2dfc)4] They are stable, paramagnetic, ionic com-... 

Tetraethylthiuram disulfide (13) induces St polymerization by the photodissociation of its S-S bond to give the polymer with C-S bonds at both chain ends (15). The C-S bond further acts as a polymeric photoiniferter, resulting in living radical polymerization. Eventually, some di- or monosulfides, as well as 13, were also examined as photoiniferters and were found to induce polymerization via a living radical polymerization mechanism close to the model in Eq. (18), e.g., the polymerization of St with 35 and 36 [76,157]. These disulfides were used for block copolymer synthesis [75,157-161] ... 

The monomers studied, 2-hydroxyethyl methacrylate (HEMA) and diethylene glycol dimethacrylate (DEGDMA), were obtained from Aldrich (Milwaukee, WI) and Polysciences, Inc. (Warrington, PA), respectively, and were used after dehibition to remove the hydroquinone inhibitor. 2,2-Dimethoxy-2-phenyl acetophenone (DMPA), the conventional initiator used in this study, was obtained from Ciba-Geigy (Hawthorne, NY) and the tetraethylthiuram disufide (TED) was obtained from Aldrich. 

Synonyms Antabuse bis(diethylthiocar-bamoyl) disulfide TETD tetraethylthiuram disulfide Thiuram E... 

National Toxicology Program Bioassay of Tetraethylthiuram Disulfide for Possible Carcinogenicity (CAS No. 91-11-9). Technical Report Series No. 166. Springfield, VA, National... 

The synthesis of thionophosphorylated peptides has also been reported using (tBuO)2PNEt2 followed by dibenzoyl tetrasulfide[14°l thionation. The use of elemental sulfur is not practical due to its low solubility and the use of tetraethylthiuram disulfide is precluded since the use of this reagent does not generate the di-terf-butyl phosphorothionate. 21 The viability of the... 

Chlormolysis of tetraethylthiuram disulfide, 35, 55 Chloroacetamide, 30, 22 Chloroacetic acid, 39, 78 a-Chloroacetoacetic acid, ethyl ester, 33, 43, 45... 

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