Part I. The Kinetics and Mechanism of Addition of Hydrogen Chloride to 2,3-Dimethyl-Butadiene-1,3 in Systems of Aprotic Solvents. Part II. A Theory of Visco-Elastic Behavior and Flow Birefringence in Solutions of Rigid Rod-Like Macromolecules

The kinetics of addition of hydrogen chloride to 2,3-dimethyl- butadiene-1,3 in systems of aprotic solvents has been investigated at 25° and 35°C. The reaction of one molecule of hydrogen chloride with one molecule of diene is reversible; the rate of the forward reaction is proportional to the first power of the diene concentration and the three halves power of the hydrogen chloride concentration, while the rate of the reverse reaction is proportional to the first power of the butene chloride concentration and to the one half power of the hydrogen chloride concentration. In a system of aprotic solvents the rate of addition is inversely proportional to the basicity of the reaction medium. A mechanism is proposed wherein the reacting species are a proton-diene complex and a hydrogen chloride molecule; thus, the addition of hydrogen chloride to conjugated dienes in aprotic solvents may be viewed as a proton catalysed reaction. The general statistical mechanical theory of irreversible processes in solutions of macromolecules presented previously by John F. Kirkwood has been applied to solutions containing large rigid rod-like molecules. It has been found that orientational factors previously neglected contribute significant terms to the real part of the shear viscosity coefficient and give rise to a rigidity modulus in the presence of periodic shear waves. A simple theory of flow birefringence gives results previously obtained by other investigators.