固体酸催化合成环己酮甘油缩酮的研究

研究并比较了HY分子筛、Hβ分子筛、HZSM-5分子筛、酸化蒙脱土、SO42-/Fe2O3和H2SO4/C等固体酸催化甘油和环己酮缩合反应的催化活性。结果表明,Hβ分子筛具有最优的催化活性,以Hβ分子筛为催化剂,研究了催化剂用量、反应物摩尔比、带水剂环己烷用量、反应时间对环己酮转化率的影响,得出最佳反应条件为:催化剂用量为0.2 g/mol环己酮,n(环己酮)∶n(甘油)=1∶1.5,环己烷用量为100 mL/mol环己酮,反应时间1 h。在此条件下环己酮的转化率和主产物2-羟甲基-1,4-二氧杂螺环4,5]癸烷的选择性分别为99.5%和98.5%。然后应用量子化学方法探讨了酸催化下此反应的反应机理,求取了甘油和环己酮碳正离子反应速率控制步骤的过渡态,并根据频率分析和内禀反应坐标计算对该过渡态的合理性进行了确认,得到该步反应的活化能为120.017 kJ/mol。

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.