Thermolysis mechanism

The thermal behavior of A and B above 150°C has been studied. Both in the gas phase and in solution, each compound yields a 3 5 mixture of ,Z-l,5-cyclooctadiene (C) and Z,Z-l,5-cyclooctadiene (D). When hexachlorocyclopentadiene is present, compound E is found in place of C, but the amount of D formed is about the same as in its absence. Formulate a description of the thermolysis mechanism that is consistent with these facts and the general theory of thermal electrolytic reactions. 

Using these macroinitiators PDMS-polystyrene and PDMS-poly(methyl methacrylate) multiblock copolymers were synthesized 305). Due to the backbone Structure of these macroinitiators and their thermolysis mechanisms, the copolymers obtained... 

Figure 35 Example of random degradation mechanism thermolysis mechanism of polyfbutylene terephthalate) (PBT).

Compared with the corresponding organosilicon compounds, the Ge derivatives are less stable and decompose at lower temperatures21. Thermolysis mechanisms as deduced from gas-phase studies are consistent with the presence of germylenes as intermediates. 

A number of reports on the thermal decomposition of peroxides have been published. The thermal decompositions of f-butyl peroxyacetate and f-butyl peroxypivalate, of HCOH and a kinetic study of the acid-induced decomposition of di-f-butyl peroxide in n-heptane at high temperatures and pressures have been reported. Thermolysis of substituted f-butyl (2-phenylprop-2-yl) peroxides gave acetophenone as the major product, formed via fragmentation of intermediate alkoxy radicals RCH2C(Ph)(Me)0. A study of the thermolysis mechanism of di-f-butyl and di-f-amyl peroxide by ESR and spin-trapping techniques has been reported. The di-f-amyloxy radical has been trapped for the first time. jS-Scission reaction is much faster in di-f-amyloxyl radicals than in r-butoxyl radicals. The radicals derived from di-f-butyl peroxide are more reactive towards hydrogen abstraction from toluene than those derived from di-f-amyl peroxide. 

In summary, although the computed structural details of the reaction profile depend on the method used for calculations, the general salient mechanistic conclusion is that the dioxetane thermolysis starts with the 0—0 bond rupture to generate the 0C(H2)—C(H2)0 triplet diradical, which is followed by C—C bond cleavage to afford the final ketone products one of them is formed preferentially in its triplet excited state. Since even simple 1,2-dioxetanes still present a computational challenge to resolve the controversial thermolysis mechanism, the theoretical elucidation of complex dioxetanes constitutes to date a formidable task. 

I. K. Igumenov, Investigation of Thermolysis Mechanism of Gas Phase of Ni(II) Chelates by Mass Spectrometry, International Symposium on Chemical Vapor Deposition, CVD-XIV and EUROCVD 11, The Electrochemical Society Proceeding, Vol.97, (No.25), 1997, pp.89-96. 

Recent studies have demonstrated that the chemical homogeneity of the freeze-dried precursor in many cases has no decisive influence on its thermolysis mechanism. It is well known that thermal decomposition of solid solutions of salts can lead to the formation of individual oxides instead of complex oxide compounds. Similar phenomena were observed during thermal decomposition of amorphous freeze-dried precursors in spite of their high chemical homogeneity. " Meanwhile, the small grain size of thermolysis products and their high reactivity resulted in the fast synthesis of complex oxides soon after thermal... 

The technical/commercial importance of the arsine thermolysis mechanisms is the role of decomposition intermediates in the deleterious incorporation of carbon into the growth of MOCVD-produced GaAs. Wendt and Speckman in their investigations into the thermal decomposition of arsines show the crucial importance of the production of AsHj radicals in the formation of low-carbon GaAs. 

In order to explain the thermolysis mechanism, the effects of reaction temperature, BSD concentration, and reaction medium on the yield of the thermolysis products have been investigated (44), and the nature of radical side products and the dependence of their yield on the reaction conditions have been studied (46). In addition, the decomposition of undeuterated and deuterated BSD has been carried out and followed by ESR (47). The results are briefly outlined here. 

Interestingly, a detailed picture of both the thermolysis mechanisms and the role of bonds which compose poly(B-alkylaminoborazines) on the degree of crosslinking and processability could be provided by synthesizing asymmetric 5-alkylaminoborazine models. We developed a route through the two-step nucleophilic reaction of 5-trichloroborazine with various amine derivatives yielding molecular compounds 1-3 [37]. Comparison was made with the symmetric 5-trimethylaminoborazine (4) that provided melt-spinnable polymers as described above (Figure 14.5). 

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