Radicals, anti-Markovnikov polymerization

Taylor in 1925 demonstrated that hydrogen atoms generated by the mercury sensitized photodecomposition of hydrogen gas add to ethylene to form ethyl radicals, which were proposed to react with H2 to give the observed ethane and another hydrogen atom. Evidence that polymerization could occur by free radical reactions was found by Taylor and Jones in 1930, by the observation that ethyl radicals formed by the gas phase pyrolysis of diethylmercury or tetraethyllead initiated the polymerization of ethylene, and this process was extended to the solution phase by Cramer. The mechanism of equation (37) (with participation by a third body) was presented for the reaction, - which is in accord with current views, and the mechanism of equation (38) was shown for disproportionation. Staudinger in 1932 wrote a mechanism for free radical polymerization of styrene,but just as did Rice and Rice (equation 32), showed the radical attack on the most substituted carbon (anti-Markovnikov attack). The correct orientation was shown by Flory in 1937. In 1935, O.K. Rice and Sickman reported that ethylene polymerization was also induced by methyl radicals generated from thermolysis of azomethane. 

Another side reaction in the polymerization of acrylates could be the anti-Markovnikov addition of Co—H to the olefinic double bond. This reaction shown in Scheme 11 was suggested to explain the absence of any methyl group in the polymer backbone of acrylamide radically polymerized in the presence... 

The Stereochemistry of Chlorination at C3 of (S)-2-Chloropentane 473 Anti-Markovnikov Addition of HBr 481 Radical Polymerization of Ethene (Ethylene) 484... 

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