the stereospecific polymerization of conjugated dienes began in 1954 with the first catalysts obtained by combining ticl4 or ticl3 with aluminum-alkyls, i.e. the catalytic systems previously employed for ethylene and propylene polymerizations. subsequently, many other catalytic systems were obtained and examined by a combination of transition metal or lanthanide compounds with appropriate alkyl...

BACKGROUND Cancer is the second leading cause of death among U.S. children with few known risk factors. There is increasing interest in the role of air pollutants, including benzene and 1,3-butadiene, in the etiology of childhood cancers. OBJECTIVE Our goal was to assess whether census tracts with the highest benzene or 1,3-butadiene ambient air levels have increased childhood lymphohematopoi...

--The macrophage content of cell suspensions from naturally occurring mouse tumours has been assessed by the Fc-mediated phagocytosis assay, and the results compared with the individual tumour's capacity for spontaneous metastasis and with its pulmonary colonization potential after i.v. inoculation. It was found that these tumours differ in their properties from the transplantable fibrosarcomas...

The crossed molecular beam reactions of the meta-tolyl radical with 1,3-butadiene and D6-1,3-butadiene were conducted at collision energies of 48.5 kJ mol(-1) and 51.7 kJ mol(-1). The reaction dynamics propose a complex-forming reaction mechanism via addition of the meta-tolyl radical with its radical center either to the C1 or C2 carbon atom of the 1,3-butadiene reactant forming two distinct i...

A retrospective mortality analysis and prospective morbidity and haematological analyses were performed for Shell Deer Park Manufacturing Complex (DPMC) male employees who worked in jobs with potential exposure to 1,3-butadiene from 1948 to 1989. 614 employees qualified for the mortality study (1948-89), 438 of those were still employed during the period of the morbidity study (1982-9), and 429...

regioselective diels-alder reactions of acyl-1,4-benzoquinones 1 with, severally, isoprene, trans-piperylene,1-acetoxy-1,3-butadiene and 1-methoxy-1,3-butadiene gave the corresponding adducts 2 in high yield. treatment of the adducts 2 with manganese dioxide gave regiospecifically the corresponding 1,4-naphthoquinones 3. in several cases, the adducts of the acetylquinones afforded intermediates...

Selective 1,2-hydrosilylation of 1,3-dienes is a challenging problem in transition metal catalysis. Butadiene, specifically, would be a useful substrate because 3-butenylsilane products have promise as superior coupling reagents for hybrid organic/inorganic materials synthesis. We report the first selective 1,2-hydrosilylation of conjugated dienes including butadiene. Hydrosilylation proceeds t...

1,3-Butadiene (CAS No. 106-99-0) was studied for potential carcinogenicity and chronic toxicity by inhalation in B6C3F1 mice. Groups of 50 mice of each sex were exposed to 0, 625, or 1250 ppm 1,3-butadiene for 6 hr/day, 5 days/week for 60 weeks (male) or 61 weeks (female). The study was scheduled for 104 weeks of exposure but was terminated early because of reduced survival related to induction...

Isoprene (2-methyl-1,3-butadiene) was selected for toxicologic evaluations because of its structural similarity to 1,3-butadiene, a potent rodent carcinogen. Two-week inhalation toxicology studies of isoprene were conducted in F344 rats and B6C3F1 mice at exposure concentrations of 0, 438, 875, 1750, 3500, or 7000 ppm. For rats, there were no chemically related changes in survival, body weight ...

The combination of a neodymium borohydride, Nd(BH4)3(THF)3 (1) or Cp*Nd(BH4)2(THF)x (2), with MgBuEt (BEM), affords an efficient and highly selective (up to 96.7% 1,4-trans) catalyst for butadiene polymerization. In the presence of excesses of Mg co-catalyst, polymer chain transfer takes place between neodymium and magnesium, and significant amounts of 1,2-units are observed. When considered fo...