Solvent can influence kinetics and mechanism of a chemical reaction. Herein, the different behavior of solvent media on the competitive mechanism between benzaldehyde (1), 4-ethylaniline (2) and diethyl acetylenedicarboxylate (3) has been described when solvent was changed from acidic pH range (formic acid in the previous work) to values near or above neutrality (ethanol in the recent work). Experimental documents was obtained using UV-vis and stopped-flow spectrophotometry techniques. The results showed that the reaction in the presence of ethanol followed second order kinetics with respect to benzaldehyde (1) and 4-ethylaniline (2), while it was second order kinetics in previous work (formic acid) in relation to 4-ethylaniline (2) and diethyl acetylenedicarboxylate (3). A speculative mechanism involving five steps was proposed that the first step encountered the largest energy barrier as a ratedetermining step (RDS). Furthermore, the influences of temperature and concentration on the reaction rate were investigated. Activation parameters (DH6¼, DS6¼ and DG6¼ ) along with kinetics values (kove and Ea) were determined. The reaction was entropy controlled in ethanol as a solvent.
کلید واژگان :---------
ارزش ریالی : 600000 ریال
با پرداخت الکترونیک