Synthesis of unsaturated nitriles via liquid-solid phase transfer catalysis: kinetic study

Abstract This study is aimed at the synthesis of unsaturated nitriles, such as 4-pentenonitrile or 3,3-dimethyl-3-butenonitrile. Solid-liquid phase transfer catalysis provides a valuable synthesis route to the preparation of C 5 nitriles. In order to better understand the general reaction mechanism, we have chosen a model reaction: cyanide displacement with 1-chlorobutane using acetonitrile as solvent and 18-crown-6 as transfer agent. Conductimetric results indicates that the 18-crown-6-KCN complex formation and its ionic dissociation are not limiting steps in the displacement reaction. Kinetic studies lead to a second-order rate equation, which can be degenerated into a first-order reaction. The non-linear dependence of the rate constant on the crown ether concentration may be attributed to the effect of complexation-ionisation equilibria. A general discussion of the experimental data obtained is presented.