| Abstract: | The kinetics of the quaternization of poly(4-vinyl pyridine) with 1-bromopropane in sulfolane has been studied in the temperature range 308–348°K with data points covering the whole conversion range. The results have been analyzed according to the neighbouring-group model with rate constants k0, k1, and k2 for reaction of pyridyl groups with zero, one, and two already reacted neighbors. Allowing for limiting reaction at about 95%, the experimental results substantiate the model with K = k1/k0 = 0.80 ± 0.03, and L = k2/k0 = 0.37 ± 0.03, which are independent of temperature. The temperature dependence of k0 values gives an activation energy of 66.22 ± 4.20 kJ mol?1. It is still not possible to decide whether steric or electrostatic factors are responsible for K and L values less than unity. Other systems are mentioned where side reactions occur. |
