Study on the condensation of cyclohexanone with glycerol using different solid acid catalysts

The condensation of cyclohexanone with glycerol was carried out using different solid catalysts such as molecular sieve HY,molecular sieve Hβ,molecular sieve HZSM-5,acid-treated montmorillonite,SO2-4/Fe2O3 and H2SO4/C.The results demonstrated that Hβ zeolite is an excellent catalyst for this reaction.The highest conversion of cyclohexanone and the selectivity of 1,4-dioxaspirodecane-2-methanol reached 99.5% and 98.5% in 1 h,respectively,by using Hβ zeolite as the catalyst under the optimum reaction conditions:0.2 g Hβ zeolite per mol cyclohexanone,molar ratio of cyclohexanone to glycerol was 1 ∶1.5,100 mL cyclohexane per mol cyclohexanone.Quantum chemical method was employed to investigate the mechanism of the reaction catalyzed by acid.The transition state of the reaction between glycerol and cyclohexanone carbocations was acquired.By using frequency analysis and inner reaction coordinate analysis the rationality of this transition state was affirmed.And the energy barrier of this reaction was determined to be 120.017 kJ/mol.