## Kinetic analysis of new multi-component reaction for the formation of Z-N-(3-(naphthalene-2-yl)-4-oxothiazolidine-2-ylidene) benzamide

2019-09-28T10:06:36Z (GMT) by

A new three-component reaction was studied kinetically among benzoyl isothiocyanate (1), 1-naphthylamine (2), and methyl bromoacetate (3) in the presence of triethylamine (4) as a catalyst, to yield Z-N-(3-(naphthalene-2-yl)-4-oxothiazolidine-2-ylidene) benzamide (5). The overall reaction is a combination of two reactions; 1) reaction a, between (1) and (2) forming 1-benzoyl-3-(naphthalen-1-yl) thiourea (P1); 2) reaction b, between (P1), (3) and (4) to form the product (5). The rate of reaction a, () was more than the reaction b (, in acetonitrile solvent at 25 °C. A mechanism was proposed involving step1 (${k}_{obs}^{a}$), step2 (k2), step3 (k3) and step4 (k4). Substituent effects with electron-withdrawing groups on para-position of benzoyl isothiocyanate (1) increased the rate constants of ${k}_{obs}^{a}$ and k2. The large negative entropy, ΔS, values in reactions a, and b are in agreement with step1 (${k}_{obs}^{a}$) and step2 (k2), an associative mechanism with a negative ΔS. The sum of these observations proved that the rate-determining step (RDS) is step2. It seems that the most important steps in the reaction mechanism are step1 (${k}_{obs}^{a}$) and step2 (k2), which strongly control the reaction process. The kinetics and mechanism of these reactions were assessed by UV–vis spectrophotometry.