Establishing a new conductance stopped-flow apparatus to investigate the initial fast step of reaction between 1,1,1-trichloro-3-methyl-3-phospholene and methanol under a dry inert atmosphere

Abstract

In the present work, for the first time, investigation of the initial fast step of reaction between 1,1,1-trichloro-3-methyl-3-phospholene (TCMP) and methanol was studied under a dry inert atmosphere by a newly constructed CSF apparatus by means of a further development in the configuration of the previous stopped-flow spectrophotometer (SFS). Hence, it was necessary to make many changes to the stopped-flow apparatus: replacement of the spectrophotometer amplifier with a conductance amplifier and the use of a conductivity cell to replace the optical one. The conductivity cell was made of polyethylene capillary tube (1 mm internal diameter; i.d.) and its inside dimensions were 1 mm i.d. × 3 mm long. Two tube electrodes which are made of stainless steel (0.8 mm i.d. × 14 mm long) were fixed at opposite ends of the observation cell and their outer surfaces were connected to the conductivity bridge amplifier by the two lead wires. The mixer was a 3-way Teflon valve and the distance between the mixer and the end of the observation cell was 30 mm. For each run, at least 24 µL of solution was required for a typical trace with a dead time of about 5 ms. Because of the extreme sensitivity of TCMP to moisture, the stopped-flow (CSF) apparatus was used inside a glove bag under a dry nitrogen atmosphere. Kinetic parameters for pseudo first-order reaction involving k(obs) = 30 s(-1) at 22 °C and activation energy E(a) = 13.55 KJ mol(-1) were successfully calculated for the initial fast step of the reaction between TCMP and methanol at 22 °C.

Reaction kinetics of CO2 in aqueous methyldiethanolamine solutions using the stopped-flow technique

“…The Bio-Kine software that controls stopped-flow experiments provided such a fitting option to extract rate constants directly from the measured data. The kinetic equation (11) expressed in terms of conductance that is proportional to the concentration is commonly used in analysing the first-order kinetic traces in a stopped-flow apparatus with a conductivity detection (Li et al 2007, Khorassani et al 2011). …”

Experimental and Theoretical Insight into the Kinetics and Mechanism of the Synthesis Reaction of 2,3-Dihydro-2-phenylquinazolin-4(1H)-one Catalyzed in Formic Acid

“…In this work for the first time, we describe experimental and theoretical kinetic results together with the detailed mechanistic studies for 2,3‐dihydro‐2 phenylquinazolin‐4(1 H )‐one catalyzed in formic acid based on a global kinetic analysis methodology. The stopped‐flow technique is most commonly used when fast reactions are involved , and in the present work there was a significant proof for determining the fast step of the reaction. Also, the kinetic data regarding the overall reaction was gained using the UV–vis spectrophotometry technique; this technique is generally preferred over IR and NMR spectroscopy because (a) it is more sensitive so more dilute solutions may be used and (b) water and other common solvents present fewer problems with UV–vis than with IR and NMR methods .…”

“…Also, the kinetic data regarding the overall reaction was gained using the UV–vis spectrophotometry technique; this technique is generally preferred over IR and NMR spectroscopy because (a) it is more sensitive so more dilute solutions may be used and (b) water and other common solvents present fewer problems with UV–vis than with IR and NMR methods . Moreover, theoretical methods are used for obtaining thermodynamic and kinetic data that are important for the accepting prophecy of the chemical reaction mechanism and also a possible interpretation of experimental findings .…”

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

“…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.…”