相转移催化法实现聚苯乙烯的功能化转变

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.

Functionalization Transform of Polystyrene by Phase-Transfer Catalysis

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.