Addition reaction of 1,6-diiodoperfluorohexane with ethylene: Process optimization and kinetic study

Abstract

The fluorine-containing compound with symmetrical structure (I-C₂H₄-(CF₂)_n-C₂H₄-I) is a widely used the intermediate of fluorine-containing copolymer having various applications in the organic fluorine chemical industry. Herein, the addition reaction of 1,6-diiodoperfluorohexane (I-C₆F₁₂-I) with ethylene was studied at different temperatures (130 to 170 °C), reaction time (4 to 12 h), solvents (acetonitrile, DMF, Py, n-hexane) and initiators (AIBN, DTBP, CuI, CuCl). The yield of the product (I-C₂H₄C₆F₁₂C₂H₄-I) was up to 73 % under optimal reaction conditions (150 °C, 10 h, CuI, acetonitrile). The kinetic equation of the reaction was derived through further studies on the reaction kinetics. The addition reaction is a consecutive reaction, the reaction order and the activation energy of the first step (I-C₆F₁₂-I to I-C₆F₁₂C₂H₄-I) are 1.131 and 56.53 kJ mol^-1, and the reaction order and the activation energy of the second step (I-C₆F₁₂C₂H₄-I to I-C₂H₄C₆F₁₂C₂H₄-I) are 0.479 and 49.81 kJ mol^-1. These are important results that allows for further process intensification and designing of reactor.