Acta Phys. -Chim. Sin. ›› 2006, Vol. 22 ›› Issue (01): 86-91.doi: 10.3866/PKU.WHXB20060117

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Effect of Organic Electrolyte on Chloromethylation of Polystyrene in Micellar Catalytic System

GAO Bao-jiao; ZHANG Xin; LIU Qi-fa   

  1. Chemical Engineering Department, North University of China, Taiyuan 030051, P. R. China
  • Received:2005-05-23 Revised:2005-06-21 Published:2006-01-15
  • Contact: GAO Bao-jiao

Abstract: Organic electrolyte tetrabutyl ammonium bromide ((Bu)4NBr, TBAB) was added into micellar catalysis system in which chloromethylation reaction of polystyrene was carried out, and the effect of TBAB on the catalytic reaction was investigated. The experiment results show that the adding of TBAB speeds up obviously the chloromethylation reaction of polystyrene in the micellar catalytic systems in which nonionic surfactant NP-10 and anionic surfactant SDS are used, especially in the system in which non-ionic surfactant NP-10 is used the acceleration is more distinct. On the contrary, in the micellar catalytic systems in which cationic surfactant CTAB is used, TBAB hardly influences the reaction rate. On one hand the reason for this may attribute to the decrease of critical micelle concentration of SDS and the increase of solubilization of polystyrene in the micellar solution because of adding electrolyte TBAB, on the other hand, a more primary reason is that organic cation (Bu)4N+ of TBAB may be embedded into micelles due to the synergistic effect of electrostatic attraction and hydrophobic interaction between butyl groups and the hydrocarbon chains of SDS , so that the inhibiting effect of anionic head groups of SDS for the nucleophilic substitution reaction that is a controlling step is weakened. Under hydrophobic interaction, organic cation (Bu)4N+ of TBAB may also be combined on the surface of NP-10 micelles, so that the surface of NP-10 micelles charged positively accelerates distinctly the nucleophilic substitution reaction. For CTAB system, the cation (Bu)4N+ can not be closed to the micelles of CTAB owing to electrostatic repellence, so the adding of TBAB can not speed up the rate of chloromethylation reaction of polystyrene.

Key words: Micellar catalysis, Surfactant, Organic electrolyte, Hydrophobic interaction, Polystyrene, Chloromethylation