固体超强酸S_2O_8~(2-)/SnO_2-SiO_2催化合成环己酮1,2-丙二醇缩酮

采用沉淀-浸渍法制备了固体超强酸S2O28-/SnO2-SiO2,以它为催化剂催化环己酮和1,2-丙二醇合成了环己酮1,2-丙二醇缩酮;考察了带水剂种类及用量、酮醇摩尔比、催化剂用量、反应时间对产品收率的影响,并用正交实验对反应条件进行了优化。实验结果表明,适宜的反应条件为:n(环己酮)∶n(1,2-丙二醇)=1∶1.6、催化剂用量为反应物料总质量的2.0%、带水剂环己烷用量5.0mL、反应时间50min。在此条件下,环己酮1,2-丙二醇缩酮收率达到91.47%;催化剂的稳定性良好,在重复使用5次后环己酮1,2-丙二醇缩酮收率为82.20%,活性下降的主要原因为催化剂表面积碳和吸附了有机物;经傅里叶变换红外光谱和气相色谱质谱分析表明,产物为环己酮1,2-丙二醇缩酮,纯度为100%。

Synthesis of Cyclohexanone 1,2-Propanediol Ketal Catalyzed by Solid Superacid S_2O_8~(2-)/SnO_2-SiO_2

Cyclohexanone 1,2-propanediol ketal was synthesized from cyclohexanone and 1,2-propanediol on S2O2-8/SnO2-SiO2 solid superacid catalyst. The catalyst was prepared by precipitation-impregnation method. Influencing factors of end product yield were investigated. Orthogonal experiment was used to optimize reaction conditions. The optimal reaction conditions are: n(cyclohexanone) ∶n(1,2-propanediol) 1 ∶1.6,catalyst mass fraction in the total reactants 2.0%,cyclohexane as water-entrainer 5.0 mL and reaction time 50 min. Under the above conditions the yield of cyclohexanone 1,2-propanediol ketal is 91.47%. S2O2-8/SnO2-SiO2 catalyst is excellent in stability and reusability,and yield of cyclohexanone 1,2-propanediol ketal keeps at 82.20% after being used for 5 times. Catalyst deactivation is mainly due to covering of active sites by organic substances from reacting solution and coking. The product was identified by means of FTIR and GC-MS. The purity of cyclohexanone 1,2-propanediol ketal is almost 100%.