2414.     NEGISHI, R., KIMURA, O., AND KAMIIKE, O.  Hydrocarbons From Carbide.  Rev. Phys. Chem. Japan, vol. 15, 1941, pp. 31-41; Chem. Abs., vol. 35, 1941, p. 6501.

        Many hydrocarbons can be synthesized directly from CaC₂, without first preparing C₂H₂ to be polymerized later.  The free energy of formation is calculated for a number of chain hydrocarbons and cyclic hydrocarbons, both from CaC₂ and H₂O to produce hydrocarbon and CaO and also from CaC₂, CO, and H₂ to form hydrocarbon and CaCO₃.  The free-energy changes are very large, especially for the hydrocarbons with the greater number of C atoms.  The ∆F at 300° is 83.5 kg.-cal. greater for the preparation of benzene from CaC₂ and H₂O, than from C₂H₂, and the increase in ∆F is even larger for similar syntheses of 1,3-butadiene or n-octane.  The affinity of CaC₂ for H₂O, and of CaO formed during the reaction for CO₂, may increase the reaction rate by effectively removing these reaction products.  The temperature coefficients of the reactions in which CaCO₃ is formed are greater than those in which CaO is formed.  The addition of CaC₂ and the greater reactivity of nascent C₂H₂ molecules result experimentally in a faster rate and greater yield of polymerized C₂H₂ than is obtained by catalytic polymerization with a Co-Ni-Cr₂O₃ clay catalyst or a Fe-Ni-kieselguhr catalyst.