1,4-Polyisoprene hydrochlorinated

On the other hand, the fact that the methyl resonances appear as sharp singlets at 1.53 ppm for the hydrochlorinated product and at 1.69 ppm for the hydrobrominated product indicates the exclusiveness of Markownikoff s rule for the addition of either hydrogen halide to the repeating units of 1,4-polyisoprene. 

The empirical shift parameters calculated from the NMR data of the 1,4-polyisoprene derivatives will provide, hereafter, a basis for assigning the carbon resonances observed in the spectrum of hydrochlorinated 1,4-polydimethyl butadiene, which like hydro-chlorinated 1,4-polyisoprene has quaternary carbons substituted by one chlorine atom. 

Synthetic polyisoprene rubbers were found by Harries during 1910 [19], to be successfully hydrochlorinated. These synthetic polyisoprenes resemble natural rubber, which is also a polymer of isoprene which occurs naturally and therefore hydrogen chloride is rapidly added when the rubber is exposed to it thus forming a protective film of chlorinated rubber or hydrogen chloride. Polybutadiene, and butadiene acrylonitrile rubbers do not add hydrogen chloride from hydrochloric acid. 

The addition of hydrogen chloride to unsaturated elastomers has also received considerable attention. Extensive work has been done on the hydrochlorination ofHevea [poly(ds-l,4-l,4-isoprene)] andBalata [poly(rraMs-l,4-isoprene)] mbbers since 1940 (Staudinger, 1944 Gordon and Tyler, 1953). Both cis-1,4 and trans c/s-l,4-polyisoprenes readily add hydrogen chloride following Markovnikov s rules with only a small amount of cyclization. 

---