## Abstract

The kinetics of the copolymerization of sulphur dioxide with cis-2-butene and trans-2-butene have been investigated dilatometrically. Both reactions show the 'ceiling temperature' effect, and from the variation of the reaction rate with temperature and composition of the reaction mixture, the changes in entropy and heat content accompanying the reaction have been determined. The heat content changes have also been measured by adiabatic calorimetry. The thermodynamic quantities obtained for the reaction (2-C$_{4}$H$_{8}$ + SO$_{2}$)$_{\text{liq.mixt.}}\rightarrow \frac{1}{n}$($\chembond{1,0} $C$_{4}$H$_{8}$SO$_{2}$$\chembond{1,0} $) (solution in monomer mixture) were cis system: $\Delta $H = -19$\cdot $3$\pm $0$\cdot $3 kcal mole$^{-1}$, $\Delta $S$^{0}$ = - 66$\cdot $3$\pm $0$\cdot $9 cal mole$^{-1}$ deg. C$^{-1}$, trans system: $\Delta $H = -20$\cdot $1 $\pm $ 0$\cdot $1 kcal mole$^{-1}$, $\Delta $S$^{0}$ = -71$\cdot $6 $\pm $ 0$\cdot $3 cal mole$^{-1}$ deg. C$^{-1}$, the standard state for $\Delta $S$^{0}$ being 1 mole l.$^{-1}$ for each reactant. In calculating the values from the kinetic data allowance has been made for the concurrent cis-trans isomerization reaction described in part IV. The values of $\Delta $H, together with the known differences in heat content of the cis- and trans-2-butene when dissolved in liquid sulphur dioxide (see part IV), indicate that the heat content of a monomeric segment of the dissolved polymer formed from cis-2-butene exceeds the heat content of a segment of the dissolved polymer derived from trans-2-butene by 2$\cdot $33 $\pm $ 0$\cdot $6 kcal mole$^{-1}$. Possible stereoisomerism of the polymer chains which might account for the discrepancy is discussed.