Catalytic Activity of Phase Transfer Catalyst in a Third Phase

• Published in: KAGAKU KOGAKU RONBUNSHU Vol. 21; no. 4; pp. 715 - 722
• Main Authors: Itoh, Hajime, Ido, Tadaatsu, Yamaguchi, Ken, Goto, Shigeo
• Format: Journal Article
• Language: English; Japanese
• Published: Tokyo The Society of Chemical Engineers, Japan 1995; Kagaku Kōgaku Kyōkai
• Subjects: Ammonium Salt; Benzyl Sulfide; Catalyst; Catalytic Activity; Chemical Reaction; Phase Transfer; Phosphonium Salt
• ISSN: 0386-216X; 1349-9203
• DOI: 10.1252/kakoronbunshu.21.715

In a phase transfer catalytic system, a third phase (referred to as a middle phase) was developed with dodecane (organic phase), sodium sulfide saturated water (aqueous phase), and ammonium salts or phosphonium salts with molecular weights of 322-507. Catalytic activity of the middle phase was tested by the reaction of benzyl chloride (in a organic phase) and sodium sulfide (in a aqueous phase). The catalytic activity was strongly dependent on experimental conditions such as the molecular weight of catalyst, concentration of sodium sulfide and the ratio of organic phase to aqueous phase. Four kinds of catalysts with different molecular weights were tested in this study. In the case of hexadecyl tri-n-butylphosphonium bromide catalyst (with the highest molecular weight), the rate of reaction was dependent on the concentration of sodium sulfide and a maximum rate was observed. In the case of tetra-n-butylammonium bromide catalyst (with the lowest m.w.), the activity appeared only when the concentrations of sodium sulfide was near saturation. In the case of tetrahexylammonium bromide catalyst (with medium m.w.), the rate of reaction in creased with concentration of sodium sulfide, and the activity was the highest. The differences in activity for the different molecular weights could be explained by the difference of hydrophilicity and lipophilicity of the middle phase. When toluene was used as an organic phase, the middle phase was not developed and the catalyst could be used as an ordinary phase transfer catalyst. The same reaction was compared for these four catalysts with toluene as an organic phase. The catalytic activities of these catalysts were higher when the middle phase was developed.