Cyclopolymerization diallyl monomers

The very high levels of head addition and the substituent effects reported in these studies are inconsistent with expectations based on knowledge of the reactions of small radicals (see 2.3) and are at odds with structures formed in the intermolecular step of cyclopolymerization of diallyl monomers (see 4.4.1.1) where overwhelming tail addition is seen. 

The observation by Matsumoto et al. (see 4.3.1.4) that significant amounts of head addition occur in polymerization of simple ally] monomers brings into question the origin of the small amounts of six-membered ring products that arc formed in cyclopolymerization of simple diallyl monomers (Scheme 4.14). If the intcrmolecular addition step were to involve head addition, then the intramolecular step should give predominantly a six-membered ring product (14) (by analogy with chemistry seen for 1,7 dienes - see 4.4.1.4). Note that the repeat units 14 and 16, like 12 and 17 are the same however, they are oriented differently in the chain. 

Diallyl monomers find significant use in cyclopolymerization (Section 4.4.1). Transfer to monomer is of greater importance in polymerizations of allyl than it is in diallyl monomers.184 This might, in part, reflect differences in the nature of the propagating species [e.g. a secondary alkyl (115) v.v a primary alkyl radical (116)]. Electronic factors may also play a role,185... 

DADMAC 13C, for example, can be readily polymerized imder these cyclopolymerization conditions to yield PolyDADMAC in which a structure composed of 5-membered A -heterocycles predominates. 13C will readily polymerize at 35°C employing ammonium persulfate as the initiator. 13C is readily copolymerized with other diallyl monomers, with acrylamide monomers such as 28C or diacetone acrylamide, or quaternized 1C. Extensive reviews of cyclopol5mieriza-tion and cyclocopolymerization can be found in Reference 188. Recent examples of cyclocopolymerization with sulfobetaine (14C) and carboxybetaine (15C) diallyl ammonium monomers are given in References (188-191). 

Ugur I, Vleeschouwer FD, Tuzun N, Aviyente V, Geerlings P, Liu S, Ayers PW, Proft FD (2009) Cyclopolymerization reactions of diallyl monomers exploring electronic and steric effects using DFT reactivity indices. J Phys Chem A 113 8704—8711... 

Polymerization. The cyclopolymerization of substituted diallyl-amino monomers has been described in a number of previous papers (1, 2,12,13) and the polymerization mechanisms and polymer structures have been worked out in considerable detail (14). The monomers with a single diallylamino substituent such as I (Equation 1) form relatively perfect polypyrrolidene structures with cis substituted rings predominating over trans by a ratio of about 5 1. 

The probability of cyclopolymerization by diallyl o-phthalate by various possible ring closures was calculated by Haward [34]. He predicted that 31% of the monomer units in the soluble polymer were cyclized. Experimentally, Simpson and co-workers [32] found that 41% were involved. This was considered excellent agreement between calculated predictions and empirical observations. 

In dilute solution, it was found that even diallyl terephthalate was capable of undergoing intramolecular cyclization. In general, with decreasing monomer concentration in a solvent, such as benzene, the possibility of cyclopolymerization increases [45]. 

The most extensive research and development activity has involved diallyl o-phthalate. The studies on the cyclopolymerization of this monomer have already been discussed at length in Section 3 of this chapter. Diallyl isophthalate polymerizes more rapidly than the the ortAo-isomer. It cyclizes less during the early stages of polymerization. Consequently the prepolymer of the isophthalate has more reactive double bonds available for further reaction than the o-phthalate and the final resin produced from it is more highly cross-linked [91]. 

The diallyl esters of maleic and fumaric acid have found application primarily in copolymer systems. Considering that the distance between the two allyl groups of the maleate ester is similar to those of the o-phthalate, and that of the fumarate is geometrically quite different, it is unfortunate that there seems to have been no study of the cyclopolymerization possibilities of these monomers. In addition there are the problems associated with the copolymerization of an allyl grouping with the double bond of the maleic or fumaric moieties within the same molecule. 

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