Oxidation of butadiene

Oxygen has also been shown to insert into butadiene over a VPO catalyst, producing furan [110-00-9] (94). Under electrochemical conditions butadiene and oxygen react at 100°C and 0.3 amps and 0.43 volts producing tetrahydrofuran [109-99-9]. The selectivity to THF was 90% at 18% conversion (95). THF can also be made via direct catalytic oxidation of butadiene with oxygen. Active catalysts are based on Pd in conjunction with polyacids (96), Se, Te, and Sb compounds in the presence of CU2CI2, LiCl2 (97), or Bi—Mo (98). 

The products of electrochemical oxidation of conjugated dienes are considerably affected by the reaction conditions such as the material of the electrode, the supporting electrolyte and the solvent. The oxidation of butadiene with a graphite or carbon-cloth anode in 0.5 M methanolic solution of NaClCU mainly yields dimerized products along with small amounts of monomeric and trimeric compounds (equation 5)1. The use of platinum or glassy carbon mainly gives monomeric products. Other dienes such as isoprene, 1,3-cyclohexadiene, 2,4-hexadiene, 1,3-pentadiene and 2,3-dimethyl-l,3-butadiene yield complex mixtures of isomers of monomeric, dimeric and trimeric compounds, in which the dimeric products are the main products. 

Extension of the Kunii-Levenspiel bubbling-bed model for first-order reactions to complex systems is of practical significance, since most of the processes conducted in fluidized-bed reactors involve such systems. Thus, the yield or selectivity to a desired product is a primary design issue which should be considered. As described in Chapter 5, reactions may occur in series or parallel, or a combination of both. Specific examples include the production of acrylonitrile from propylene, in which other nitriles may be formed, oxidation of butadiene and butene to produce maleic anhydride and other oxidation products, and the production of phthalic anhydride from naphthalene, in which phthalic anhydride may undergo further oxidation. 

Kolbe oxidation of carboxylate ions to radicals with loss of carbon dioxide (p. 312). The latter process gives highest yields of dimeric product at a platinum anode and only monomeric products from oxidation of the radical centre at a carbon anode. Oxidation of butadiene in methanol containing benzoic acid, at a smooth platinum anode, gives 45 % of the but-3-ene-l,4-diol diester [45]. 

For V2O5-P2O5 oxide particles strongly adsorbed in a zeolite a change in the usual selectivity has been observed. Indeed, the oxidation of butadiene with dioxygen stops at the level of furan and not at maleic anhydride on V2O5-P2O5-HY. 

The rarb products are 0.7, 0.7, and 0.9 for the co-oxidations of butadiene with cumene, Tetralin, and styrene, respectively. Hence, there is little variation among the selectivities of the peroxy radicals from these hydrocarbons and butadiene. 

Table VI. Reactivity Ratios in Co-Oxidations of Butadiene, Styrene, Tetralin, and Cumene at 60°C. ...

Akimoto and Echigoya (232) have studied the reactivity of 02 on supported Mo03 in the catalytic oxidation of butadiene and this is discussed in Section VI. 

Akimoto and Echigoya (232) have studied the oxidation of butadiene over... 

Table 19. Fmaj/ mapp values of the NADPH-dependent oxidation of butadiene and epoxybutene, as determined in cell fractions and used for physiological toxicokinetic modelling...

Krause. R.J. Elfarra, A.A. (1997) Oxidation of butadiene monoxide to meso- and (+-)-diepoxy-butane by cDNA-expressed human cytochrome P450s and by mouse, rat, and human liver microsomes evidence for preferential hydration of /MC5o-diepoxybutane in rat and human liver microsomes. Arch. Biochem. Biophys., 337, 176-184... 

Less is known about the combustion pathway. Using IR spectroscopy, formate, carboxylate, bidentate carbonate, monodentate carbonate, and acetate bands have been observed when butene is adsorbed on Surface degradation (oxidation) of butadiene has also been observed on a-Fe203 at room temperature (34). 

The oxidation of butadiene, diallyl carbonate, or diallyl ether gives the products of monoepoxidation with selectivities of 85% and higher when the ratio diene/H202 is 2.5 (Table VIII). The diepoxides are formed in larger amounts when the diene/H202 ratio is 1. 

The selectivity in the formation of 1,4-diacetoxy-2-butene (1,4-DAB) is considerably enhanced when tellurium compounds are used as cocatalysts. Thus a heterogeneous catalyst, prepared by impregnation of Pd(N03)2 and Te02 dissolved in HN03 over active charcoal (Pd/Te = 10), can be used for the oxidation of butadiene (by 02 in AcOH at 90 °C) to 63% trans-l,4-DAB, 25% cis-1,4-DAB and 12% 3,4-diacetoxy-l-butene. Conventional soluble catalysts such as Pd(OAc)2/Li(OAc) are much less selective in the formation of 1,4-DAB 429 The gas-phase 1,4-diacetoxylation of butadiene in the presence of Pd-Te catalysts is currently being industrially developed by Mitsubishi and BASF 430... 

An alternative mechanism may include first an O-inserhon step, followed by the transformation of the oxidized compound into the cyano-containing compound. An example might be the oxidation of butadiene to maleic anhydride followed by hydrolysis to the acid, the formation of the diamide and the oxydehydrogenation to the dinitrile. 

Investigation of the sol-gel derived bismuih-molybdcnum-titanium xerogel and aerogel mixed oxide as catalyst for the oxidation of butadiene to furan l 14J 15] indicated activities and selectivities comparable to other suitable catalysts. The unique microstructure and good catalytic performance of the bismuth molybdenum oxide particles are attributed to lilania matrix. How ever, these favorable properties are limited to low temperature reaction conditions since both xerogels and aerogels are prone to rapid restructuring at elevated temperatures, which result in the loss of their unique redox properties. 

The rate of oxidation of purified methylvinylpyridine rubber (a copolymer containing 85% butadiene and 15% 2-methyl-5-vinylpyridine) within the interval 50-90°C substantially exceeds the rate of oxidation of butadiene rubber (SKB). 

Fig. 50 Activation energies for oxidation obtained from different kinetic characteristics for thermal oxidation of butadiene a-methyl styrene copolymer (black), poly(p-divinyl benzene (grey) and polystyrene (white). The data were taken from [06J2].

Bond, G., Sarkany, A. and Parfitt, G. (1979). The Vanadium Pentoxide-titanium Dioxide System. Structural Investigation and Activity for the Oxidation of Butadiene, J. Catal., 57, pp. 476-493. 

Akimoto and Echigoya, based on their study of M0O3 + Ti02 catalyzed oxidation of butadiene, dihydrofuran (2, 5-DHF), and furan, argue that butadiene oxidizes to MA via two pathways ... 

Akimoto and Echigoya have studied the oxidation of butadiene on a Mo-Ti catalyst. They observed a linear relationship between the concentration of Mo species and rate of CO2 formation. However, rate of MA formation increases nonlinearly. It was concluded that only one Mo site is involved in the rate-controlling step during CO2 formation, whereas more than one site was necessary for MA formation. They also conclude from their... 

Correlation between the catalytic activity for oxidation of butadiene and the acid amount of catalyst, b... 

Titania is often combined with other oxides to form binary systems. Cao et al. [248,249] and Yoda et al. [250,251] have investigated the applicability of titania and titania-silica aerogels as potential oxidation catalysts for removal organics from air (VOCs) or water. The concept is to combine the gas adsorption properties of silica with the photocatalytic activity of titania in a mixed catalysis system. Bismuth-molybdenum-titanium xerogel and aerogels are promising catalysts for the oxidation of butadiene to ftiran, where reported activities and selectivities are comparable to state-of-the-art industrial catalysts [252]. 

Wildberger, M.D., Madejewski, M., Grunwaldt, J.-D. et al (1999) Sol-gel bismuth-molybdemun-titanlum mixed oxides II. Oxidation of butadiene to l xt3n.AppL Catal A, 179 (1-2),... 

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