C3 cyclopolymerization

The cyclopolymerization of the title compound (St-Cj-St), C3 cyclopolymerization, is reviewed. The polymerization has the similar behavior to the fluorescence emission of 1,3-diphenylpropane and its derivatives (n=3 rule or C3 rule). The monomer and its derivatives were prepared by the convenient method from the corresponding a-phenethylalcohol derivatives, using dimethyl sulfoxide-ZnCl2 CCl3COOH system. St-C3 St gave a cyclopolymer only by cationic initiators, and the presence of cyclized units in the main chain was elucidated by several spectroscopic analyses and also by the isolation of cyclocodimers obtained from the reaction of the monomer with styrene in the presence of the catalytic amount of CF3SO3H. 

C3 cyclopolymerization has not yet been finished and has still some interesting unsolved problems as mentioned in this paper. A few of initial objects, however, have been accomplished. That is, it gave the new material which has high n-basicity due to cyclophane units. The future progress is hoped to present further more novel materials produced by the principle of C3 cyclopolymerization where the attractive interaction between cationic site and aromatic n-system functions during the polymerization. 

The cyclopolymerization is revealed to be extremely sensitive to the structure of the monomer. Among the monomers investigated, St-C3 St, l,4-bis(2.-vinyl-phenyl)butane (St-C -St), 1,3-bis(p-vinylphenyl)butane,... 

Before the discussion on the fact that the radical initiators failed to cyclopolymerize St-C3 St, we need the close examination of examples for the synthesis of the [3.3]paracyclophane skeleton. Because, for the syntheses of strained cyclic compounds like [3.3]-paracyclophane, the properties of intermediates formed during reactions seem to affect the cyclization of open-chain starting materials. 

It means that St-Ci,-St is cyclopolymerized less readily than St-C3—St by E F3OEt2 It is because a C-C bond in methylene linkage of St-Ci,-St should be arranged in eclipsed conformation at the transitioi state (IV). 

It is well known that 1,1-diphenylethylene is not homopoly-merized so that the cyclopolymerization of 1,3-bis[ -(1-phenyl-vinyl) phenyl]propane (DE-C3-DE) is hardly expected (38). The... 

On the effect of the modification of the benzene rings in St-C3-St on the cyclopolymerization, we have still not had much information. It will be interesting to polymerize monomers substituted at benzene rings symmetrically or unsymmetrically by some groups. At the present moment, we have only one example, the polymerization of VN-Cj-VN, which has more bulky groups but wider TT-systems than St-Cj-St (22). Although more detailed works are still needed to compare the data of the cyclopolymerization of VN-C3-VN with those of St-C3 St, the monomer seems to be cyclo-polymerized equally readily to St-C3-St The rc values, the cyclization constant defined by Aso and his associates (41), for the cyclopolymerizations of St-C3-St and VN-C3-VN were 0.15 mol/... 

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