A STUDY OF CUPRENE FORMATION

Abstract

The copper oxide catalyzed polymerization of acetylene to cuprene has been studied between 230° and 330 °C. by the flow method. The reaction shows an initial induction period at the lower temperatures followed by a rapid rise to a maximum rate and a more gradual decrease. With increase in temperature the induction period becomes shorter, and the maximum rate attained becomes greater. If commenced at 330 °C. the reaction is explosive. Analysis of the exit gas shows considerable ethylene and some free hydrogen, the amounts increasing with the temperature of the reaction. This indicates that the hydrogen split off in cuprene formation does not bear a constant ratio to the amount of cuprene formed. The yield of cuprene based on acetylene reacting is about 85% of theory, which is 4 to 10% lower than values based on a volume contraction of acetylene alone.An exponential equation has been derived which expresses the rate of absorption of acetylene at 290 °C. over a period of 72 hr. under the conditions of the experiment. The equation is integrated to give the quantity of acetylene absorbed at any time. This makes a prediction of yields possible. The heat of polymerization was calculated from the determined heat of combustion of cuprene. Various theories regarding the mechanism of formation and structure of cuprene are discussed, and the photochemical evidence of a chain reaction is supported.