Study On Reactions Between Calcium Carbide And Methanol, Ethanol, Isopropanol

The growing gap between oil production and oil demand in this century has promoted research and development of coal conversion technologies. As one of the main intermediate products of many coal to fine chemicals processes, calcium carbide has continuously played an important role in the past and may become more important in the future.The current calcium carbide based technologies are, however, all via acetylene or acetylene based, which require pre-conversion of calcium carbide, by reacting with water. The notable ones include the production of polyvinyl chloride, acetylene black, lime nitrogen and vinyl acetate. Since calcium carbide and acetylene both have a carbon-carbon triple bond, it is possible to prepare products directly from reactions of calcium carbide. This may lead to reduction in production costs for some of the current processes and more importantly to inventions for production of other chemicals, as evidenced recently by the preparation of elemental carbon. Furthermore, the direct reaction of calcium carbide may allow concurrent reactions of acetylene that may also be advantageous. It was reported in1960s that vinyl ether can be produced by reacting calcium carbide with alcohol. These reactions may become important in the near future because the increased production of calcium carbide and alcohols, including the coal derived methanol and the biomass derived ethanol. The understanding of these reactions up to date, however, is far from sufficient and even questionable.In this paper, reactions of calcium carbide individually with three alcohols, methanol, ethanol and isopropanol, are studied. The main conclusions obtained are:(1) Besides the products reported in the literature, calcium alkoxides and vinyl ethers, acetylene is a major product, which is produced from the reaction of calcium carbide with the alcohols rather than that with water.(2) The reaction pathway of calcium carbide and alcohols includes formation of acetylene and calcium alkoxides in the first step and then the reaction of acetylene with alcohols for vinyl ethers in the second step.(3) The calcium alkoxides may undergo decomposition that yields alcohols with carbon atoms more than that of the reactants.