Application Of CaC₂/C₂H₂ In CCl₄ Conversion And Cinnamonittrile Synthesis

Due to the characteristic energy structure of China,i.e.rich coal,deficient oil,and lean gas,the coal chemical industry developed rapidly in recent years,and so is the calcium carbide sector of coal chemical industry.Calcium carbide is an important basic chemical and widely used in organic synthesis,agrochemical production,metallurgy and other fields,but its high energy consumption in production and limited downstream products limit its further development.Therefore,development of new applications of calcium carbide is of great significance for the wealthy development of coal chemical industry.By using calcium carbide as an acetylene source,many chemicals have been synthesized,e.g.propargyl alcohol,vinyl ether,propargylamine,and pyrrole etc.,but the reaction of calcium carbide or acetylene with halogenated hydrocarbons is rarely reported.Firstly,we studied the reaction of acetylene and carbon tetrachloride for the production of chloroform and tetrachloroethylene.The effects of the reaction temperature,reaction time,and catalyst amount on the reaction were discussed,and the reaction mechanism was speculated.Second,considering the least safety of acetylene gas in industrial applications,we studied the reaction of CC14 with acetylene in situ formed by hydrolysis of calcium carbide,so as to enhance the intrinsic reavtion safety.Finally,to explore its applicability of strong basicity and dehydration ability,the catalysis of CaC2 is studied for the condensation reaction of cyclohexanone and acetonitrile to produce cyclohexeneacetonitrile.The main conclusion and achievements are as follows.(1)Under basic conditions,hydrogen-chloride exchange reaction between acetylene and carbon tetrachloride can take place at room temperature under the help of a phase transfer catalyst,giving rise to the production of chloroform and tetrachloroethylene simultaneously.The stronger the basicity of the catalyst is,the higher the conversion rate of carbon tetrachloride is,and tetrabutylammonium fluoride(TBAF)is found to be the best phase transfer catalyst investigated.Considering the mild reaction conditions,high reaction rate and selectivity to chloroform in the absence precious metal catalysts,the present reaction route is of great significance for industrial application.(2)Using calcium carbide as the source of acetylene,its reaction with CCl4 under alkaline conditions in DMSO solvent is studied in order to convert carbon tetrachloride to chloroform.The highest conversion rate of CCl4 is obtained by using cesium carbonate as an alkali catalyst,and presence of trace water is crucial for the reaction.Compared with the reaction between acetylene gas and carbon tetrachloride,the present reaction is easier to manipulate,safter,and without using phase transfer catalyst.The reaction can be carried out by directly dissolving calcium carbide,carbon tetrachloride and trace water in DMSO solvent,the addition of an alkali catalyst is beneficial to improve the conversion rate of carbon tetrachloride.(3)As a base catalyst,CaC2 can catalyse the condensation reaction of benzaldehyde and acetonitrile synergistically with CsF for the production of cinnamonitrile.Wherein,CsF is used to activate the alpha-H of via deprotonation.The conversion rate of benzaldehyde and the yield of cinnamonitrile increased with the increasing temperature.The reaction is fast,and benzaldehyde can be converted completely withinin 1 h.The catalyst amount has a significant effect on the reaction,and too much catalyst can induce side reactions.The strong alkalinity and strong dehydration ability in the reaction system is justified.The present process is simple with high reaction efficiency and cinnamonitrile yield,which is of reference significance for expanding new uses of calcium carbide in the future.