Kinetic Aspects of Tetrahydrobenzo[b]pyran Formation in the Presence of Agar as a Green Catalyst: A Mechanistic Investigation

Abstract

The kinetic and mechanism of the reaction between benzaldehyde, malononitrile and dimedone has been studied in the presence agar as a highly efficient homogenous catalyst in a mixture of (water/ethanol, 2:1). Based on the experiment data, the overall order of reaction for the formation of tetrahydrobenzo[b]pyran followed second-order kinetics and under pseudo-order conditions the partial orders with respect to 1, 2 and 3 were one, one and zero, respectively. From the temperature, concentration and solvent studies, the activation energy (E a ) and the related kinetic parameters (Δ Δ Δ Δ ΔG ‡ , Δ Δ Δ Δ ΔS ‡ and Δ Δ Δ Δ ΔH ‡ ) are calculated. The first step of the proposed mechanism is recognized as a rate-determining step (k 1 ) and this is proved by the steady state approximation.

Insight into the Reaction Mechanism of α‐Amino Phosphonate Synthesis Using Succinic Acid as a Catalyst: Computational Kinetic Approach

“…There can be several suggested mechanisms for a reaction, but a typical organic reaction proceeds in a specific manner. In order to derive a better understanding of a desired mechanism in comparison with the experimental mechanism, a speculative theoretical mechanism involving four steps for these reactions is illustrated in Scheme in accordance with the reports in the literature and experimental kinetic data …”

“…In previous works, we have investigated the kinetics of the syntheses of some new organic compounds such as phosphorus ylides, pyran derivatives, phosphonate esters, and so on, both experimentally and theoretically . Experimental procedures suffer from various constraints, such as trapping the transition states (TSs) or intermediates, in corroborating the pathway through which the reactions proceed.…”

Effect of Reactivity on Kinetics and a Mechanistic Investigation of the Reaction between Dimethyl Acetylenedicarboxylate and 1,3-Dicarbonyl Compounds in the Presence of a Catalyst: A Spectrophotometric Approach

“…Thus, arsonium ylides react frequently in the form of ylide B ( Figure 2) faster than phosphonium ylides. Although the kinetics and mechanistic investigations of some reactions with TPP have been reported previously [6][7][8][29][30][31][32][33], no attempts for similar reactions with TPA have been reported. www.prkm.co.uk…”

Kinetics and related studies of the formation of 2,3‐dihydroquinazolin‐4(1H)‐ones in the presence of different benzaldehyde derivatives

“…A number of methods have been developed to obtain experimental kinetic data and analyze them to arrive at a true explanation of the reaction mechanism. Numerous kinetic researches over a large area of different reactions have previously been reported using the UV/vis technique . The main purpose of this study is to achieve a general overview on the kinetic behavior of the reaction between 2‐aminobenzamide with benzaldehyde in the presence of formic acid as a catalyst for the generation of 2, 3‐dihydroquinazolin‐4(1H)‐ones (Scheme ).…”