缩醛交换反应制备双二乙二醇丁醚缩甲醛

报道了一种以二乙二醇丁醚（DEGB）和二乙氧基甲烷（DEM）为原料，通过磷钨酸催化下的缩醛交换反应，合成双二乙二醇丁醚缩甲醛（BDEGBF）的新方法；与甲醛相比，二乙氧基甲烷可作为一种绿色的反应试剂应用于缩醛交换反应。考察了催化剂种类、催化剂用量、原料配比、反应温度、反应时间等因素对缩醛交换反应的影响。结果表明：当磷钨酸催化剂用量为二乙二醇丁醚质量的1.0%，原料配比n（DEM）：n（DEGB）=3：1，反应温度为80℃，反应时间为90min时，DEGB的转化率达到最高为84.9%。磷钨酸催化剂回收方便，可重复使用6次。通过FTIR和¹H NMR对产物结构进行表征，并提出了缩醛交换反应可能的反应机理。本缩醛制备方法具有多个优点，例如反应条件温和、环境友好、操作简便，还具有一定的醇醚类底物普适性。

Preparation of bis(diethylene glycol butyl ether) formal by acetal exchange reactions

A novel approach for the synthesis of bis(diethylene glycol butyl ether) formal via acid-catalyzed acetal exchange reactions with diethylene glycol butyl ether and diethoxymethane was reported. Compared with formaldehyde, diethoxymethane was greener as thereagent. The effects of catalyst type, dosage of the catalyst, the ratio of the reactants, reaction temperature and reaction time on acetal exchange reaction were investigated. The results showed that the maximum conversion of 84.9% could be obtained with diethylene glycol butyl ether:diethoxymethane=1:3 in mole and in the presence of 1.0% phosphotungstic acid at 80℃ for 90min. The phosphotungstic acid catalyst could be reused for 6 times. The product was characterized by FTIR and ¹H NMR.The reaction mechanism of the exchange reaction was also provided. The method for the preparation of bis(glycol ether) acetals has several advantages, such as mild reaction conditions, friendly environment, simple operation and wide glycol ether substrates scope.