A precision conductance apparatus for studying fast ionic reactions in solution

Tregloan, Peter A.; Laurence, G.

doi:10.1088/0950-7671/42/12/310

Cited by 31 publications

(10 citation statements)

References 10 publications

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“…In addition, it has been suggested earlier that the kinetics of ionic species' phenomena (e.g., the fourth step) are very fast. [48][49] If the first step (rate constant k 2 ) were the rate determining step, in this case, two reactants (triphenylphosphine 1 and dialkyl acetylenedicarboxylate 2), as we see (Figure 3), have no charge and could not form strong ion-dipole bonds to the high dielectric constant solvent, 1,2-dichloroethane. However, the transition state carries a dispersed charge which here is divided between the attacking 1 and 2 and, hence, bonding of solvent to this dispersed charge is much stronger than to the reactants, which lack charge.…”

Section: Effect Of Concentrationmentioning

confidence: 89%

Synthesis of stable phosphorus ylides from 3, 5-dimethylpyrazole and kinetic investigation of the reactions by UV spectrophotometry

Habibi‐Khorassani¹,

Maghsoodlou²,

Nassiri³

et al. 2007

Arkivoc

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Stable crystalline phosphorus ylides were obtained in excellent yields from the 1:1:1 addition reactions between triphenylphosphine and dialkyl acetylenedicarboxylates, in the presence of a NH-acid, such as 3,5-dimethylpyrazole. These stable ylides exist in solution as a mixture of two geometrical isomers as a result of restricted rotation around the carbon-carbon partial double bond resulting from conjugation of the ylide moiety with the adjacent carbonyl group. To determine the kinetic parameters of the reactions, they were monitored by UV spectrophotometery. The second order fits were drawn and the values of the second order rate constant (k 2 ) were calculated automatically 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 good agreement with the Arrhenius equation. This provided the relevant plots to calculate the activation energy of all reactions. Furthermore, useful information was obtained from studies of the effect of solvent, structure of reactants (different alkyl groups within the dialkyl acetylenedicarboxylates) and also concentration of reactants on the rate of reactions. The 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.

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Section: Effect Of Concentrationmentioning

confidence: 89%

Synthesis of stable phosphorus ylides from 3, 5-dimethylpyrazole and kinetic investigation of the reactions by UV spectrophotometry

Habibi‐Khorassani¹,

Maghsoodlou²,

Nassiri³

et al. 2007

Arkivoc

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show abstract

“…In addition, it has been suggested earlier that the kinetics of ionic species ' phenomena (e.g. the fourth step) are very fast [48][49][50] . This step cannot be the ratedetermining step like steps 5 and 6.…”

Section: (11)mentioning

confidence: 97%

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

Habibi‐Khorassani¹,

Maghsoodluo²,

Ebrahimi³

et al. 2012

Orientjchem.

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For the first time, kinetic studies were made of the reactions between triphenyl phosphite 1, dialkyl acetylenedicarboxylates 2 in the presence of NH-acid, such as 3, 4-dicholoro aniline (as a protic/nucleophilic reagent) 3 for the generation of compound 4 with gauche arrangement and [(2S * , 3S * ) or (2R * , 3R * )] configuration. To determine the kinetic parameters of the reaction, monitoring was conducted using UV spectrophotometery. The second order fits were automatically drawn and the values of the second order rate constant (k 2 ) were automatically calculated using standard equations within the program. All reactions were repeated at different temperature ranges, the dependence of the second order rate constant (Ln k 2 ) and (Ln k 2 /T) on the reciprocal temperature were in good agreement with Arrhenius and Eyring equations, respectively. This provided the relevant plots to calculate the kinetic and activation parameters (Ea, ΔH # , ΔS # and ΔG # ) of all reactions. Furthermore, useful information was obtained from studying the of the effect of solvent, structure of reactants (dialkyl acetylenedicarboxylates) and also concentration of reactants on the reaction rates. The proposed mechanism was confirmed according to the obtained results and steady state approximation. The first and third steps (k 2 , k 3 ) of all reactions were recognized as rate determining and a fast steps, respectively on the basis of experimental data. Herein, theoretical calculations have been employed for the assignment of the most stable isomers ([(2S

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“…The highly stereo-selective synthesis has previously shown that compound 4a has a gauche arrangement with [(2S * , 3S * ) or (2R * , 3R * )] configuration [32]. For assignment of the two possible configurations [(2S * , 3S * ) or (2R * , 3R * )] and [(2S * , 3R * ) or (2R * , 3S * )] isomers in 4a, first their structures were optimised at the HF/6-31G (d,p) level of theory by the Gaussian 03 program [25].…”

Section: Theoretical Calculationmentioning

confidence: 99%

Mechanistic Study of the Formation of a Phosphonate Ester Containing 2-Fluoroaniline: Theoretical Assignment of the Resulting Isomer

Habibi‐Khorassani

Maghsoodluo

Ebrahimi

et al. 2013

Progress in Reaction Kinetics and Mechanism

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For the first time, theoretical calculations have been employed for assignment of the most stable isomers ([(2S*, 3S*) or (2R*, 3R*)] and [(2S*, 3R*) or (2R*, 3S*)] of a phosphonate ester containing 2-fluoroaniline at HF/6-31G(d,p) and B3LYP/6-311++G(d,p) levels of theory. The results were showed that the compound with gauche arrangement and [(2S*, 3S*) or (2R*, 3R*)] configuration was more stable than the anti arrangement with [(2S*, 3R*) or (2R*, 3S*)] geometry. In addition, experimental 1H, 13C and 31P NMR data along with X-ray crystallographic data of the compound were consistent with the results obtained from theoretical calculations. Kinetic studies were performed on the reaction between triphenyl phosphite, dialkylacetylene dicarboxylates in the presence of an NH-acid, namely as 2-fluoroaniline (as a protic/nucleophilic reagent) for the generation of the compound with a gauche arrangement and [(2S*, 3S*) or (2R*, 3R*)] configuration. Kinetic data were obtained spectrophotometrically and a temperature study yielded activation parameters. A mechanistic scheme is proposed which fits all the kinetic data.

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A precision conductance apparatus for studying fast ionic reactions in solution

Cited by 31 publications

References 10 publications

Synthesis of stable phosphorus ylides from 3, 5-dimethylpyrazole and kinetic investigation of the reactions by UV spectrophotometry

Synthesis of stable phosphorus ylides from 3, 5-dimethylpyrazole and kinetic investigation of the reactions by UV spectrophotometry

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

Mechanistic Study of the Formation of a Phosphonate Ester Containing 2-Fluoroaniline: Theoretical Assignment of the Resulting Isomer

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