Cross-reactions sulfonyl group

The catalyst system mentioned above does not work for aliphatic aziridines. However, after changing the iV-sulfonyl group from tosyl to cinsyl (32) the cross-coupling reaction of aliphatic aziridines can be carried out by NiCla glyme catalysis (Scheme 14.39). In this case carbon-carbon bond formation on the least-substituted side of the aziridine is favoured, the ratios of the regioisomers being from 2.5 1 to 4.9 1. ° ... 

Exercise 29-6 Radical-induced chlorination of polyethene in the presence of sulfur dioxide produces a polymer with many chlorine and a few sulfonyl chlo-- ide (—S02CI) groups, substituted more or less randomly along the chains. Write suitable mechanisms for these substitution reactions. What kind of physical properties would you expect the chlorosulfonated polymer to have if substitution is carried to the point of having one substituent group to every 25 to 100 CH2 groups How may this polymer be cross-linked (A useful product of this general type is marketed under the name of Hypalon.)... 

Obviously, the incorporation of an electron-withdrawing substituent in the polymer-supported benzotriazole ring should enhance its reactivity. Thus, the sulfonamide-substituted HOBt resin 34 (Section 7.3) has been obtained by reaction of aminomethylated divinylbenzene cross-linked polystyrene with the sulfonyl chloride 116 to give supported sulfonamide 117, followed by typical hydroxybenzo-triazole formation (Scheme 7.37) [128]. The effect induced by the sulfonamide group was determined by measuring the acidity of non-polymeric analogues, showing a pKa of 3.59 for the sulfonamide-substituted HOBt, and a pKa of 4.64... 

The Maleimide cure system is similar to the sulfur donor system in that it involves the decomposition of the sulfonyl chloride cure site. In this case, however, the Maleimide (meta-toluene-bis-maleimide, HVA-1 or meta-phenylene-bis-maleimide, HVA-2) rather than sulfur, is involved in the cross-links, and there is no evidence of a metal ionic bond. The reaction is usually initiated with an amine involving either an amine-catalyzed decomposition of the sulfonyl chloride group or a path of radical anions. The most recently developed initiators, which have been found to give a balanced combination of... 

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