Efficient Catalysis of Calcium Carbide for the Synthesis of Isophorone from Acetone

The liquid-phase aldol condensation of acetone for the synthesis of isophorone (IP) was studied under catalysis of CaC2 powder for the first time. The reaction products were analyzed by gas chromatography, gas chromatography–mass spectrometry, and X-ray diffraction. The catalytic behavior of CaC2 was studied at varying temperature, particle size, and dosage and compared with that of Ca(OH)2 and other basic catalysts. It was found that CaC2 shows excellent catalytic performance because of its strong Lewis basicity and dehydrating ability, and CaC2 is converted to Ca(OH)2 and acetylene simultaneously by the resulting water. Higher temperature, smaller catalyst size, and higher mass ratio of CaC2 are beneficial to the IP synthesis. The overall catalytic performance of CaC2 is superior to that of all basic catalysts reported heretofore. This process combines the hydrolysis of CaC2 and the aldol condensation of acetone into a one-pot reaction, which promotes the condensation of acetone greatly along with the quantitative reclamation of acetylene. Thus, this process can be thought of as a green, cost-effective, and efficient route for the synthesis of IP and provides a valuable use of CaC2.