4-Chloro-2-hexene

In conclusion, it may be said that a lot of literature has been published that favors the Frye and Horst mechanism of stabilization. Most of this is based on studies done on low-molecular weight model compound for al-lylicchlorines in PVC, i.e., 4-chloro-2-hexene. Although the large contribution of these studies toward understanding the mechanism of stabilization of PVC cannot be denied, the extrapolation of these results to the processes involved in the actual stabilization of the polymer should be done with extreme care. The polymer represents a complex mixture of macromolecules, which in the melt is not only physically a very different system compared to the low-molecular weight model compound, but invariably contains, apart from stabilizers, other additives, such as plasticizers, lubricants, processing aids, etc., that further complicate the situation. The criticism of the Frye and Horst mechanism is also based on solid experimental evidence, and hence, the controversy is still very much alive. 

The extent of C-alkylation as a side reaction in etherification varies about 1% of allyl 2-allylphenyl ether is formed when phenol is used in the acetone and potassium carbonate method with allyl bromide with cinnamyl bromide or 7,7-dimethylallyl bromide the extent of C-alkylar tion is greater.16 A complicated mixture of C- and O-alkylation products results from the treatment of phenol with 4-bromo-2-hexene and 4-chloro-2-hexene. 9 4-Hexenylresordnol has been obtained in about 40% yield from the reaction of l-bromo-2-hexene, resorcinol, and potassium carbonate in boiling acetone.99 An appreciable amount of C-alkylation occurs when 2,6-dimethyIphenol is treated with allyl bromide and sodium ethoxide in ethanol.70 Since, in general, the ampunt of C-alkylation is greatly increased by carrying out the alkylation on the sodium salt of the phenol in benzene,16 this method is unsuitable for the preparar tion of allyl aryl ethers. 

Table II includes the reaction half-time (6410 minutes) calculated for the unimolecular hydrogen chloride elimination for 4-chloro-2-hexene...

C6H11CI 4-chloro-2-hexene 6734-98-1 396.15 34.967 1,2 8112 C6H11NO 5,5-dimethyl-1-pyrroline N-oxide 3317-61-1 474.25 41.416 2... 

With Miscellaneous Compounds. Several mechanistic studies have been performed recently on reactions of "auxiliary stabilizers with 4-chloro-2-hexene, both in the presence and in the absence of metal salts (82,87,88, 89,90). The stabilizers used were phosphites (82,87), phosphines (82,87), epoxides (88), 2-phenylindole (89), and the bis(j8-aminocrotonate) ester of 1,4-butanediol (90). Important mechanistic features delineated in this work included substitutive removal of allylic... 

At a temperature above 80 °C, poly (vinyl chloride) eliminates hydrogen chloride and allylic chlorinated structures appear, with 4-chloro-2-hexene being considered as a model. At the processing temperature (180-200°C), the main problem of poly (vinyl chloride) stabilization is preventing the zip dehydrochlorination that induces discoloration and cross-linking of the polymer. 

In the zinc-calcium formulations, metal soaps are associated with secondary stabilizers such as alkylphosphites, epoxy compounds, a-phenyl-indole, or -aminocrotonate esters that bring a synergistic effect. The first attempt to study the mechanisms behind this effect has been the reaction of all of these compounds with 4-chloro-2-hexene. 

Zinc stearate (I) reacts with 4-chloro-2-hexene to yield hexenyl stearate and zinc chloride, which is a strong catalyst for this esterification reaction as well as for the degradation reaction that yields hexadiene and... 

This reaction was clarified with hexenyl stearate (I) at 60°C during the reaction between zinc stearate and 4-chloro-2-hexene in tetrahydro-furan. During this reaction, zinc stearate reacts immediately with 2 mol of model compound, and kinetic laws do not suggest the presence of CIZnOCOR as an intermediate product in the substitution reaction. Nevertheless, such an organometallic compound was suggested by Frye and Horst (9) and also by Anderson and McKenzie (10) who assumed that such compounds accounted for the ligand exchange between cadmium chloride and barium carboxylate. 

These results show that a-phenylindole does not influence zinc chloride formation and that it may catalyze the substitution reaction of allylic chlorine atoms on the polymer as it catalyzes the esterification reaction of 4-chloro-2-hexene (6). But its accumulation quickly implies discoloration. From these experiments, it is clear that a-phenylindole is a shortterm stabilizer that only impedes initial coloring. Nevertheless, the darkening develops as quickly as the cross-linking. These results account also for Ta variations, implying that the time prior to cross-linking is not very... 

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