Kinetics and Mechanism Investigation of the Reaction between Triphenylphosphine, Di‐tert‐butyl Acetylenedicarboxilate and OH‐Acid

Abstract

Kinetic studies were made for the reaction between triphenylphosphine, di-tert-butyl acetylenedicarboxilate in the presence of OH-acid, such as 2-hydroxy-4-methoxybenzaldehyde. To determine the kinetic parameters of the reaction, it was monitored by UV spectrophotometery. The second order fits were automatically drawn by the software associated with a Cary UV spectrophotometer model Bio-300 at appropriate wavelength. The values of the second order rate constant (k 2 ) were calculated using standard equations within the program. At the temperature range studied the dependence of the second order rate constant (ln k 2 ) on reciprocal temperature was in a good agreement with Arrhenius equation. This provided the relevant plots to calculate the activation energy of the reaction. Furthermore useful information was obtained from studies of the effect of solvent and concentration of reactants on the rate of reaction. Proposed mechanism was confirmed according to the obtained results and steady state approximation and first step (k 2 ) of reaction was recognized as a rate-determining step on the basis of experimental data. In addition, assignment of more stable isomers (Z or E) was investigated using the theoretical study.

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

“…Equation (19), is a rate law for the first-order kinetic reaction which is not in agreement with the experimental results [Eqn (7)]. The acceptable rate law [Eqn (15)] depends on the concentration of 1,3-dicarbonyl compounds (ACAC or DBM).…”

“…Since compound TPA is a catalyst, its concentration is constant so the rate law can be written www.prkm.co.uk where (16) Equation 15is compatible with the second-order experimental rate law [Eqn (7)] which means that the two steps, step 2 and step 4 (k 2 and k 4 ), can be considered as the RDSs. As a result, step 4 is more likely to be the RDS.…”

“…Often, it is sufficient to record continuously the absorbance of a reaction mixture in a thermostated cuvette at a fixed wavelength. The required instrumentation is www.prkm.co.uk readily accessible and numerous kinetic investigations of organic reactions have been reported using the UV-Vis technique [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. The first catalytic reaction of arsonium ylides in 1989 reported that this property was vital in the synthesis of cyclopropanes with high diasteroselectivity [16][17][18][19][20].…”

A Mechanistic Investigation of Stable Phosphonate Ester Derived from 3, 4 dichloro Aniline: A Kinetics Study and Theoretical Calculations

“…In fact, in recent works triphenyl phosphite has been used instead of triphenylphosphine in the previous work. [33][34][35][36][37][38][39][40][41] In addition, the product is phosphonate esters 4 not phosphorus ylides. Synthesis of compounds 4, shown in Figure 1, has been reported earlier.…”

Synthesis of New Stable Phosphorus Ylides and 1,4‐Diionic Organophosphorus Compound from a Reaction between Hexamethyl Phosphorous Triamide and Dimethyl Acetylenedicarboxylate in the Presence of CH‐Acids

“…Phosphorus ylides are reactive intermediates, which have been used in many reactions and are involved a lot in the synthesis of organic compounds . In continuation of our investigation on the organophosphorous synthesis by trivalent phosphorus nucleophiles and following the first report for the synthesis of C ‐amino phosphorous ylides by hexamethyl phosphorous triamide , we have recently described the synthesis of new phosphorous ylides from a reaction between hexamethyl phosphorous triamide and dimethyl acetylenedicarboxylate (DMAD) in the presence of N—H acids . Herein, we wish to report a convenient and facial one‐pot, three‐component reaction between hexamethyl phosphorous triamide and DMAD in the presence of C—H acids 3a–d and 5 for the preparation of new and stable phosphorous ylides 4a–d and 1,4‐diionic organophosphorus 7 , respectively, in excellent yields at ambient temperature (Fig.…”