Allyl chloride thermal decomposition

Activated alcohols are unstable, at least at high temperature, when the corresponding radicals are able to stabilize carbocations, for example in the case of allylic alcohols. The thermal decomposition of activated allylic alcohols leads to the formation of allylic chlorides. This decomposition can... 

Allylations of hydroquinone derivatives, 32 459-461 Allyl chloride oxidation, 41 305 thermal decomposition, 41 80 tl-Allyl complexes, 25 129-134 Allyl hydroperoxide, 27 187-189 Allylic alcohols, olefinic substitution of, 26 343-345... 

Instability of the polymer is responsible for the primary step in decomposition and is attributed either to fragments of initiator or to branched chains or to terminal double bonds. The appearance of branching is the result of reactions of chain transfer through the polymer, while that of unsaturated terminal groups results from reaction of disproportionation and chain transfer through the monomer. During thermal and thermo-oxidative dehydrochlorination of PVC, allyl activation of the chlorine atoms next to the double bonds occurs. In this volume, Klemchuk describes the kinetics of PVC degradation based on experiments with allylic chloride as a model substance. He observed that thermal stabilizers replace the allylic chlorine at a faster ratio than the decomposition rate of the allylic chloride. 

Kinetic investigation revealed that thermal stabilizers replace the allylic chlorine at rates which are much faster than the unimolecular decomposition rate of the allylic chloride. This clearly establishes that the stabilizers do not act only as acid acceptors but that they are capable... 

PVC is a vinyl polymer where X is a chlorine atom in the general formula of Scheme 12.3, but its thermal decomposition follows a quite differeut pathway from that of PS, starting with division of the side groups from the main chain. When a chlorine atom is cut off from a defect point (tertiary carbon atom or allyl bond), it abstracts the hydrogen atom from the next carbon atom, then hydrogen chloride is eliminated, together with the... 

As models for the investigation of the S i and S i mechanisms the thermal decompositions of alkyl chlorosulfites and allyl chlorosulfites have received considerably more attention than that of other desulfonylation reactions. The usual method of converting alcohols into alkyl chlorides is by treatment with thionyl chloride. This reaction has been shown to proceed through an alkyl chlorosulfite which can often be isolated and shown to decompose by a homogeneous first-order process yielding alkyl chloride and 802 " , although frequently substantial amounts of alkene are formed in the reaction , viz. 

Mechanism of Nonoxidative Thermal Dehydrochlorination. This subject is still very controversial, with various workers being in favor of radical, ionic, or molecular (concerted) paths. Recent evidence for a radical mechanism has been provided by studies of decomposition energetics (52), the degradation behavior of PVC-polystyrene (53) or PVC-polypropylene (54) mixtures, and the effects of radical traps (54). Evidence for an ionic mechanism comes from solvent effects (55) and studies of the solution decomposition behavior of a model allylic chloride (56). Theoretical considerations (57,58) also suggest that an ionic (El) path is not unreasonable. Other model compound decompositions have been interpreted in terms of a concerted process (59), but differences in solvent effects led the authors to conclude that PVC degrades via a different route (59). 

In a study of the thermal and thermooxidative dehydrochlorination of poljrvinyl chloride, the opinion has been expressed that allyl activation of the chlorine atoms next to the double bonds occurs the question of the mechanism of the primary event of decomposition of the polymer remained not entirely clear [2]. 

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