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Generally polymers are unsaturated compounds like alkenes, alkalines etc. The addition polymerization mainly takes place in free radical mechanism. The free radical mechanism of addition polymerization completed by three steps i.e. Initiation of free radical, Chain propagation, Termination of chain.
In general, the adding radical attacks the alkene at the most sterically accessible (typically, least substituted) carbon; the radical then stabilizes on the more substituted carbon. [3]: 188, 751 The result is typically anti-Markovnikov addition, a phenomenon Morris Kharasch called the "peroxide effect". [4]
In these cases, the alkenes RCH=CH 2 are converted to high molecular weight alkanes (-RCHCH 2-) n (R = H, CH 3, Cl, CO 2 CH 3). Other forms of chain growth polymerization include cationic addition polymerization and anionic addition polymerization. A special case of chain-growth polymerization leads to living polymerization.
Addition reactions are also encountered in polymerizations and called addition polymerization. General overview of addition reactions. Top to bottom: electrophilic addition to alkene, nucleophilic addition of nucleophile to carbonyl and free-radical addition of halide to alkene
Some authors have broadened the definition of the Michael addition to essentially refer to any 1,4-addition reaction of α,β-unsaturated carbonyl compounds. Others, however, insist that such a usage is an abuse of terminology, and limit the Michael addition to the formation of carbon–carbon bonds through the addition of carbon nucleophiles.
In organosulfur chemistry, the thiol-ene reaction (also alkene hydrothiolation) is an organic reaction between a thiol (R−SH) and an alkene (R 2 C=CR 2) to form a thioether (R−S−R'). This reaction was first reported in 1905, [ 1 ] but it gained prominence in the late 1990s and early 2000s for its feasibility and wide range of applications.
Polyaddition (or addition polymerisation [2] [3]) is a polymerization reaction that forms polymers via individual independent addition reactions.Polyaddition occurs as a reaction between functional groups on molecules with low degrees of polymerization, such as dimers, trimers and oligomers, to form species of higher molar mass.
In polymer chemistry, radical polymerization (RP) is a method of polymerization by which a polymer forms by the successive addition of a radical to building blocks (repeat units). Radicals can be formed by a number of different mechanisms, usually involving separate initiator molecules .