相转移催化法实现聚苯乙烯的功能化转变

Functionalization Transform of Polystyrene by Phase-Transfer Catalysis

以对羟基苯甲醛的钠盐为亲核取代试剂,采用相转移催化进行了大分子氯甲基聚苯乙烯的亲核取代反应,将其转变为侧链带有功能性基团醛基的聚苯乙烯;考察了反应条件(如有机溶剂的极性、催化剂种类及用量、有机相与水相之比等)对大分子相转移催化反应的影响,并根据相转移催化反应机理与相关的动力学规律进行了分析.结果表明,通过相转移催化亲核取代反应,可将氯甲基聚苯乙烯大分子链上的氯原子转化,制得侧链带有醛基的聚苯乙烯;溶剂的极性越强,负离子的反应活性也越高;催化剂季铵正离子的亲脂性越强,相转移催化反应的速率越快.当催化剂浓度较低时,四丁基溴化铵比十六烷基溴化铵的催化效果好;当催化剂浓度较高时,十六烷基溴化铵比四丁基溴化铵的催化效果好.另外,有机相与水相之比对相转移催化反应有较大的影响.

The nucleophilic substitution reaction of chloromethylated polystyrene was performed using the sodium salt of p-hydroxybenzaldehyde as the nucleophilic substitution agent via phase-transfer catalysis, and polystyrene with aldehyde groups on its side chains was prepared. The structure of the product was characterized by FT-IR spectroscopy. The effects of various factors, such as the polarity of solvents, the kind and used amount of the catalysts, and the ratio of organic phase to water phase, on the phase-transfer catalysis reaction were studied, and these effects were analysed according to the reaction mechanism and kinetics theory. The results showed that functionalization of polystyrene could be realized by phase-transfer catalysis, the chlorine atoms on the chains of chloromethylated polystyrene could be favorably transformed, and polystyrene with aldehyde groups on its side chains was successfully obtained. For this phase-transfer catalysis system, the suitable catalyst is tetrabutylammonium bromide, the solvent with stronger polarity is favorable, and the fitting volume ratio of organic phase to water phase is equal to 1/2.