Kinetics and mechanism of the quaternization of poly(4‐vinyl pyridine) with 1‐bromopropane

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.