Unsaturated hydrocarbons consecutive reactions

A consecutive reaction mechanism was proposed by Zhang-Lin et al. (25,26). The mechanism was based on kinetics data calculated for the oxidation of butane, 1-butene, 1,3-butadiene, and furan catalyzed by (VO)2P207 and VOPO4 phases. In conbast to the results of the TAP investigations, the kinetics data suggested that furan is not an intermediate in butane oxidation, but is an intermediate in butadiene oxidation. The differences observed in the oxidation of butane and the unsaturated hydrocarbons lead to questions about the validity of extrapolating butene and butadiene oxidation results to the butane oxidation. 

The main primary product of the thermolysis with ethene was cyclopropane, provided that the alkenes were present in large excess. The observed isomerization to propene was shown to be a consecutive reaction. Cvetanovic et al. (1967) also found products that indicate the formation of allyl radical intermediates leading, in multi-step reactions, to hexa-l,3-diene, pent-l-ene, and butane. The authors assumed that these compounds resulted from recombination of allyl and ethyl radicals. It is well known from combustion chemistry that the addition of methylene precursors to unsaturated hydrocarbons leads to higher hydrocarbons as precursors of soot (see e.g., Homann and Wellmann, 1983). 

Adduct Formation of OH with Aromatics and Unsaturated Hydrocarbons and Consecutive Reactions with O2 and NOx to Regenerate OH... 

For most unsaturated hydrocarbons, addition of OH is the first and rate-limiting step of the photochemical reaction chain. In the case of aromatics, which are emitted from automobiles, forest fires and fuel wood burning [11], the addition reaction is reversible at atmospheric temperatures. The effective rate constant for removal of the aromatic depends on consecutive reactions of the adduct. Prior to LACTOZ, consecutive reactions with O2 had not been detected for benzene -OH... 

Consecutive reactions of silyl and hydrogen radicals with other molecules can only occur if reactivity and lifetime of these radicals are sufficient to enable these successive reactions to predominate over. the further decomposition of the radicals to Si and H2. Such a reaction occurs between SiH4 and hydrocarbons above the decomposition temperature of SiH4, and results in the formation of heterogeneous organosilicon compounds. Saturated and unsaturated hydrocarbons react with SiH4... 

The rate-determining process is considered to involve the conversion of the initial intermediate complex into a c-bonded 1,3-oxypalladium adduct which undergoes further rapid reactions possibly involving two specific, consecutive 1,2-hydride shifts. In the reaction with cyclohexene and other unsaturated hydrocarbons of this type under acidic conditions (I.5M-HCIO4), a fast oxidation with palladium acetate is observed, the products being cyclohexanone and other acetate-containing species. A slower oxidation is reported, however, in the presence of oxygen. 

It has been shown [90] that the homogeneous dissociation of methane is the only primary source of free radicals and it controls the rate of the overall process. This reaction is followed by a series of consecutive and parallel reactions with much lower activation energies. After the formation of acetylene (C2H2), a sequence of very fast reactions occurs, leading to the production of higher unsaturated and aromatic hydrocarbons and finally carbon ... 

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