KINETIC-STUDY OF SYNTHESIZING 2,4,6-TRIBROMOPHENOL ALLYL ETHER BY PHASE-TRANSFER CATALYTIC REACTION

2,4,6-Tribromophenol and allyl bromide undergo SN2 substitution reaction by phase transfer catalysis to produce 2,4,6-tribromophenyl allyl ether. The effects of solvents, reactant concentration, agitation rate, catalysts, and temperature on the conversion are investigated in order to find the optimum operating conditions for this reaction. It is found that no agitation effect is observed when the agitation rate exceeds 600 rpm. The order of relative activities of solvents is dichloromethane >chlorobenzene >toluene. A better choice of potassium hydroxide rather than sodium hydroxide enhances the reaction rate. In examining six kinds of phase transfer catalysts, tetra-rc-butylammonium bromide (or tetra-n-butylammonium hydroxide) is the best one. The apparent reaction rate is first order on the quantity of phase transfer catalyst and allyl bromide, respectively. The corresponding activation energy of the apparent rate constant is 13.8 kcal/mol. During the reaction, the concentration of the intermediate product was also measured to observe its behavior in the liquid-liquid system. The present study has valuable implications in the synthesis of phenyl allyl ether via the two-phase Williamson reaction. © 1990, American Chemical Society. All rights reserved.