STUDY ON THE SYNTHESIS OF DICHLOROCYCLOPROPANES BY PHASE TRANSFER CATALYSIS
| Autor: | Yu-Ming Hsieh, 謝育民 |
|---|---|
| Rok vydání: | 2003 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 91 The primary objective of this dissertation is to study the dichlorocyclopropanation of organic compounds by phase transfer catalysis. The phase transfer catalyzed reaction of chloroform and olefins was carried out in an alkaline aqueous solution of NaOH/chloroform two-phase medium. Dichlorocarbene, which is an active species to react with olefins in the organic phase, is generated from the reaction of chloroform, sodium hydroxide and phase transfer catalyst at the interface between two phases. These dichlorocyclopropanes and their derivatives can be used as the pharmaceuticals, perfumery industry and agrochemicals. The primary purpose of this work is to use phase-transfer catalytic technique to synthesize the dichlorocyclopropanes in the two-phase medium by the conventional quaternary ammonium salts, 3-(N,N-trialkylammonio)propansulfonates and the novel multi-site quaternary ammonium salt as the phase transfer catalysts. The synthesizing conditions, reaction mechanism, kinetics and the operation factors which affect the reaction were discussed. In this work, we choose tetrabutylammonium chloride (TBAC) and benzyltriethylammonium chloride (BTEAC) as the conventional phase-transfer catalysts, the dichlorocyclopropanation of chloroform and 1,7-octadiene was carried out in a low and high alkaline aqueous concentration, respectively. A third-order rate law and a pseudo first-order rate law are used to describe the reaction rate at low sodium hydroxide concentration (30 % w/w) and at high sodium hydroxide concentration solution (50 % w/w), respectively. Reasonable explanations of different reaction kinetics and the behavior in the reaction were discussed. 3-(N,N-dimetyloctylammonio)propansulfonate, which could be used to synthesize the dichlorocyclopropanes, was synthesized by dimetyloctyl amine with 1,3-propanesultone. The reactivity of this new compound is more active than those of the conventional phase transfer catalysts. This new synthesized phase transfer catalyst, 1,4-bis(triethylmethylammonium)benzene dichloride (DC-X), which possesses two-site activity, was obtained from the reaction of α,α’-dichloro-p-xylene and triethylamine. The procedure of synthesizing 1,4-bis(triethylammonium)benzene dichloride is simple and easy to purification. The reactivities of synthesizing dichlorocyclopropanes with different novel multi-site phase transfer catalysts and 3-(N,N-alkylammonio)propansulfonates were also discussed in this dissertation. In studying the kinetics, the dichlorocyclopropanation of 1-octene by 3-(N,N- dimethyloctylammonio)propansulfonate (S-8) and 4-viyl-1-cyclohexene by 1,4-bis(triethylmethylammonium)benzene dichloride (DC-X) was carried out in an alkaline aqueous solution of NaOH/chloroform two-phase medium. Kinetics of the reactions such as: effects of the catalysts, agitation speed, temperature, alkaline concentration, amount of catalyst, amount of reactant and volume of chloroform (organic solvent) on the reaction rate were investigated in detail. The pseudo first-order rate law and the interfacial reaction mechanism are well used to explain the reaction behaviors. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
| Externí odkaz: |
|