Butadiene epoxide

Butadiene, a major commodity chemical used in the production of synthetic rubber, is listed as one of 189 hazardous air pollutants under the 1990 Clean Air Act Amendments. Butadiene is a carcinogen in rats and mice, with mice being substantially more sensitive than rats. The extent to which butadiene poses risk of cancer to humans exposed to this chemical is uncertain. The data include in vitro studies on butadiene metabolism using tissues from humans, rats, and mice as well as experimental data and physiological model predictions for butadiene in blood and butadiene epoxides in blood, lung, and liver after exposure of rats and mice to inhaled butadiene (Bond et al., 1996). 

The molecular biology data suggest involvement of at least diepoxybutane in the development of cancer in rodents following butadiene exposure. However, the additive or possible synergistic involvement of one or both of the other butadiene epoxides cannot be discounted. 

Doerr, J.K., Hollis, E.A. Sipes, I.G. (1996) Species differences in tine ovarian toxicity of 1,3-butadiene epoxides inB6C3F mice and Sprague-Dawley rats. Toxicology, 113, 128-136 Downs, T.D., Crane, M.M. Kim, K.W. (1987) Mortality among workers at a butadiene facility. 

Himmelstein, M.W, Turner, M.J.. Asgharian. B. Bond. J.A. (1994) Comparison of blood concentrations of 1,3-butadiene and butadiene epoxides in mice and rats exposed to 1,3-butadiene by inhalation. Carcinogenesis. 15. 1479-1486... 

Perez, H.L., Lahdetie, J., Landin, H.H., Kilpelainen, I., Koivisto, P, Peltonen, K. Osterman-Golkar, S. (1997) Haemoglobin adducts of epoxybutanediol from exposure to 1,3-butadiene or butadiene epoxides. Chem.-biol. Interact., 105, 181-198... 

Thomton-Manning, J.R., Dahl, A.R., Beehtold, W.E., Griffith, W.C., Jr Henderson R.F. (1997) Comparison of the disposition of butadiene epoxides in Sprague-Dawley rats and B6C3F1 miee following a single and repeated exposures to 1,3-butadiene via inhalation. Toxicology, 123, 125-134... 

Valentine, J.L., Boogaard, P.J., Sweeney, L.M., Turner, M.J., Bond, J.A. Medinsky, M.A. (1997) Disposition of butadiene epoxides in Sprague-Dawley rats. Chem.-biol. Interact., 104, 103-115... 

Propylene oxide (mp, -104°C bp, 34°C) is a colorless, reactive, volatile liquid with uses similar to those of ethylene oxide. Its toxic effects are like those of ethylene oxide, though less severe. The properties of butylene oxide (liquid bp, 63°C) are also similar to those of ethylene oxide. The oxidation product of 1,3-butadiene, 1,2,3,4-butadiene epoxide, is a direct-acting (primary) carcinogen. 

Tretyakova et al. [67] reported the quantitative analysis of adducts of 1,3-butadiene epoxides with dA and dG in DNA. The butadiene metabolites 3,4-epoxy-1-butene, diepoxybutane, and 3,4-epoxy-l,2butanediol were found to react with dG at the A-7-position and dA at the jV-1-, A-3-, N-6-, and A-7-positions. Quantitative analysis of the modified nucleobases was performed by positive-ion LC-ESI-MS in SRM mode. 

Butadiene epoxidation to epoxybutene (EpB ) was practiced at a semiworks scale of 1.4 x 10 metric tons year by Tennessee Eastman [9] between 1997 and 2004 [10]. Epoxybutene is a versatile intermediate [11] that can be used to produce a large variety of different products such as epoxybutane, 1,4-butane diols and alcohols, 1,2-butane diols and alcohols, 2,3-dihydrofuran, 2,5-dihydrofuran, tetrahydrofuran, N-methylpyrrolidone, cyclopropyl carboxyaldehyde (CPCA) derivatives, vinyl ethylene carbonate (addition of CCT to EpB), and 3,4-dihydroxy-l-butene (addition of H2O to EpB). 

FIGURE 1.6 Proposed reaction network in butadiene epoxidation. 

J. W. Medlin, J. R. Monnier, M. A. Barteau, Deuterium kinetic isotope effects in butadiene epoxidation over unpromoted and Cs-promoted silver catalysts, ]. Catal. 204 (2001) 71. 

Figure 1. Gas chromatogram for unpromoted silver Figure 2. Mechanistic scheme for butadiene epoxidation. The catalyst. See Table 1 for reaction conditions. arrow widths approximate relative rates ot reaction.

As stated earlier, the product distribution during butadiene epoxidation over an unpromoted catalyst indicated that epoxybutene was strongly bound to the Ag surface and that the CsCI promoter lowered the desorption energy of epoxybutene. These observations should be reflected in the steady-state kinetics of the reaction. The data summarized in Table 5 list the steady-state reaction conditions used to determine the reaction orders for the reactants C4H6 and O2 as well the reaction products epoxybutene, CO2, and H2O. In all these experiments differential conversions of C4H6 and O2 were maintained and the data fitted to the typical power rate law expression for epoxybutene formation... 

Application of the power rate law method is straightforward for those reactions in which the reaction products do not inhibit the rate of product formation. In the case of butadiene epoxidation, the partial pressures of epoxybutene, CO2, and H2O inhibit the rate of additional epoxybutene formation. In these experiments, the effects of CO2 and H2O on the rate of epoxybutene formation can be neglected since the molar selectivity to epoxybutene was typically 98-99%, which gave very low and relatively constant amouts of CO2 and H2O in the gas stream. However, the epoxybutene formed in the reactor required the normalization of the rate of epoxybutene formation to account for the inhibition effect of epoxybutene. Finally, one ppm of 1,2-dichloroethane (DCE) was added to the feed stream to maintain constant activity for the 3-4 week period of time over which the kinetic experiments were conducted. 

If we apply the "6/7" rule (see Sachtler (17) for explanation) typically cited as evidence for the role of molecular O2 in selective epoxidation of ethylene for the case of butadiene epoxidation, we would not expect selectivity for epoxybutene to exceed "11/12", or 91.7%. In fact, selectivities of 93-96% are typically seen at all reaction conditions. Selectivities of 97-98% are observed at differential conditions and lower reaction temperatures. Therefore, based only upon the observed selectivities to epoxybutene, dissociatively-adsorbed oxygen is clearly the active oxygen in butadiene epoxidation. Further, the kinetic model, which has been derived from the kinetic plots in Figure 5 has been used to very satisfactorily fit a wide variety of reaction data from several different reactor formats, assumes dissociatively-adsorbed oxygen at both promoted and unpromoted Ag sites. The oxygen incorporated into epoxybutene is dissociatively-adsorbed oxygen, not molecular oxygen. 

Butadiene, epoxidized Single Tg II had 50 moI% epoxidation Margaritis and kalfoglou (1988)... 

Motwani, H.V., Fred, C., Haglund, J., Golding, B.T., Tornqvist, M. (2009) Cob(I)alamin for Trapping Butadiene Epoxides in Metabolism with Rat S9 and for Determining Associated Kinetic Parameters. Chem. Res. Toxicol. 22 1509-1516. 

The synthesis of organic chemicals by catalytic reactions of COj has been reviewed. Ben l and allyl halides are carboxylated electrolytically in the presence of Co(saleh) catalysts. Palladium(O) catalysts smoothly carboxylate butadiene epoxide to the carbonate a mechanism x-allyl Pd complexes is proposed (eqn.49). ... 

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