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 CaC 2 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 CaC 2 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 CaC 2 shows excellent catalytic performance because of its strong Lewis basicity and dehydrating ability, and CaC 2 is converted to Ca(OH) 2 and acetylene simultaneously by the resulting water. Higher temperature, smaller catalyst size, and higher mass ratio of CaC 2 are beneficial to the IP synthesis. The overall catalytic performance of CaC 2 is superior to that of all basic catalysts reported heretofore. This process combines the hydrolysis of CaC 2 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 CaC 2 .