The kinetics of ionic polymerisation. Part XIII. An infrared study of the iodine-catalysed polymerisation of n-butyl vinyl ether

Abstract

Rates of the iodine-catalysed polymerisation of n-butyl vinyl ether in ethylene dichloride, diethyl ether, and carbon tetrachloride have been measured by i.r. spectroscopy and dilatometry. Both methods gave similar results which fitted the third-order rate equation R_p∼k[M][I₂]². The rate constants k(50 l.² mole^–2 sec.^–1 for carbon tetrachloride, 400 l.² mole^–2 sec.^–1 for diethyl ether, and 10⁵ l.² mole^–2 sec.^–1 for ethylene dichloride) increased markedly with increasing polarity of the solvent. In accord with previous data for diethyl ether as solvent, the results for carbon tetrachloride and ethylene dichloride suggested the formation of a monomer–iodine 1 : 1 complex which is inactive in the polymerisation process. Equilibrium constants for the formation of this complex (0·7 l. mole^–1 in carbon tetrachloride and 0·2 l. mole^–1 in ethylene dichloride) have been deduced.