酸催化甘油和苯甲醛合成2-苯基-1,3-二氧六环-5-醇的研究

Synthesis of 2-phenyl-1,3-dioxan-5-ol from glycerol and benzaldehyde catalysed by p-toluenesulfonic acid

以甘油和苯甲醛为原料,对甲苯磺酸为催化剂,合成了甘油苯甲醛缩醛,该缩醛产物为2-苯基-1,3-二氧六环-5-醇(六元环)和4-羟甲基-2-苯基-1,3-二氧戊环(五元环)的混合物,考察了反应条件对总收率的影响,得出最佳工艺:苯甲醛和甘油的物质的量比为1∶1.3,石油醚用量50 m L,催化剂用量为1.5 g,反应时间4 h,得到了最大收率为95.6%(以苯甲醛计)。考察了五元环向六元环的转化条件,并在-20℃的低温条件下,以甲苯和石油醚作为混合溶剂结晶分离出六元环,纯度为95.4%。利用气质联用仪(GC-MS)、核磁共振波谱仪(1H NMR)对目标产物进行了定量和定性分析。

p-Toluenesulfonic acid was used as the catalyst for the condensation of glycerol with benzalde-hyde to mixtures of 2-phenyl-1,3-dioxan-5-ol（ the six ring）and 2-phenyl-1,3-dioxolane-4-methanol（ the five ring）. The optimum conditions were as follows：molar ratio of benzaldehyde to glycerol is 1：1. 3,the mass of catalyst is 1. 5 g,the reaction needs 4 h,and the volume of ligroin is 50 mL. Under the optimum conditions,the yield of benzaldehyde glycerol acetal showed the maximum conversion of 95. 6%. Investi-gated the transformation of the five ring to the six ring in different factors. Then,2-phenyl-1,3-dioxan-5-ol was isolated from a mixture of toluene and ligroin,the purity of the product is 95. 4%. The characteriza-tion of target products were analyzed by means of GM-MS and 1 H NMR.