690 J. Org. Chem., Vol. 42, No. 4, 1977
Reibel, Kennedy, and Chung
(29) J. Halpern and H. B. Tinker, J. Am. Chem. Soc., 89, 6427 (1967). (30) M. H. Kreevoy, L. L. Schaleger, and J. C. Ware, Trans. Faraday Soc., 58, 2433 (1962). (31) M. H. Kreevoy, N. Takashina, and L. L. Schaleger, Abstracts, 137th National Meeting of the American Chemical Society, Cleveland, Ohio, April 1960. (32) From Figure 1 it can see that point 21 (oxidation of styrene) is off the line. This can be explained by the fact that there is a resonance effect present. In the graph (Figure 1) values for the alkenes 11-18 are not plotted. The substituents on these alkenes are too great already so fhat they may cause rotation (mobile substituents) and hence hinder the admission of the thallic ion to the reaction center-this isagainst the principle of the conservation of rigidity.28In this way we have explained the relative low values of rate constants in comparison with the other RCH=CHp alkenes. (33) V. A. Palm, Usp. Khim., 30, 1069 (1961); “Osnovy Kolichestvennoi Teorii Organicheskikh Reaktsii”, Khimiya, Leningrad, 1967, p 173.
(34) J. Shorter, 0. Rev., Chem. SOC.,24, 433 (1970). (35) J. E. Leffler and E. Grunwald, “Rates and Equilibria of Organic Reactions”, Wiley, New York, N.Y., 1963, p 162. (36) G. Mouvier and J. E. Dubois, Bull. SOC.Chim. Fr., 1441 (1968). (37) Number of alkenes see Table I. The other ones are 30 (isobutene), 31 (2-methyl-l-butene), 32 (2,3,3-trimethyl-l-butene). (38) The following symbols are used: LFER, linear free energy relationships: PE, polar energy: SE, steric energy; u * , electrostatic and electronic effect of substituent (with respect to CH3); p ’ . parameter characteristic the sensibility of reaction to polar effects; E*. steric parameter of substituent with respect to CH3 raft); ESo.“right steric parameter” (Palm): 6. parameter characteristic the sensibility of reaction to steric effects: nH,number of C-H bonds in LY position with respect to substituent; nc, number of C-C bonds in LY position with respect to substituent; R,regression coefficient; S = 100R2, the number of experimental results (YO) that can be brought objectively into context with the linear regression relation.
Cationic Polymerizations by Aromatic Initiating Systems. 1. A Model for Initiation and Termination Using the ~ - C H ~ C G H ~ C H ~ System C~/E~~A~ Leonard C. Reibel,+Joseph P. Kennedy,* and Yen-Lung Chung The Institute of Polymer Science, The University of Akron, Akron, Ohio 44325 Received July 2, 1976 The interaction between p-CH&GHdCH&l and EtnAl (or EtZAlCl) has been investigated using CHgCl:! solvent in the range from -50 to -80 “C. The reaction yields three products: p-CH:&HdCHgEt, ~ - C H : G H ~ C H Land H, oligomeric polybenzyls. The first two arise upon ethylation and hydridation of the p-CH:CsH4+CHz cation by the Et.
