Reinterpretation of the kinetic data and the non-steady state hypothesis (two-step mechanism) for the SN2 reaction between p-nitrophenoxide and methyl iodide in aprotic solvents containing water

2003 ◽  
Vol 1 (11) ◽  
pp. 1969 ◽  
Author(s):  
Eduardo Humeres ◽  
T. William Bentley
Keyword(s):  
Steady State ◽  
Methyl Iodide ◽  
Kinetic Data ◽  
Aprotic Solvents ◽  
Sn2 Reaction ◽  
Step Mechanism

scholarly journals The comparative study of linear solvatation energy relationship for the reactivity of pyridine carboxylic acids with diazodiphenylmethane in protic and aprotic solvents

2012 ◽  
Vol 77 (10) ◽  
pp. 1311-1338 ◽  
Author(s):  
Sasa Drmanic ◽  
Jasmina Nikolic ◽  
Aleksandar Marinkovic ◽  
Bratislav Jovanovic
Keyword(s):  
Solvent Effects ◽  
Kinetic Data ◽  
Aprotic Solvent ◽  
Isonicotinic Acid ◽  
Linear Regression Analysis ◽  
Multiple Linear Regression Analysis ◽  
Reaction Rates ◽  
Aprotic Solvents ◽  
Pyridine Carboxylic ◽  
The Comparative Study

Protic and aprotic solvent effects on the reactivity of picolinic, nicotinic and isonicotinic acid, as well as of some substituted nicotinic acids with diazodiphenylmethane (DDM) were investigated. In order to explain the kinetic results through solvent effects, the second-order rate constants for the reaction of the examined acids with DDM were correlated using the Kamlet-Taft solvatochromic equation. The correlations of the kinetic data were carried out by means of the multiple linear regression analysis and the solvent effects on the reaction rates were analyzed in terms of the contributions of the initial and the transition state. The signs of the equation coefficients support the already known reaction mechanism. The solvatation models for all the investigated acids are suggested and related to their specific structure.

scholarly journals Reactivity of cyclohex-1-enylcarboxylic and 2-methylcyclohex-1-enylcarboxylic acids with diazodiphenylmethane in aprotic solvents

2000 ◽  
Vol 65 (12) ◽  
pp. 839-846
Author(s):  
Jasmina Nikolic ◽  
Gordana Uscumlic ◽  
Vera Krstic
Keyword(s):  
Hydrogen Bond ◽  
Rate Constants ◽  
Kinetic Data ◽  
Linear Regression Analysis ◽  
Spectroscopic Method ◽  
Reaction Rates ◽  
Aprotic Solvents ◽  
Experimental Conditions ◽  
Hydrogen Bond Acceptor ◽  
Protic Solvents

Rate constants for the reaction of diazodiphenylmethane with cyclohex-1-enylcarboxylic acid and 2-methylcyclohex-1-enylcarboxylic acid were determined in nine aprotic solvents, as well as in seven protic solvents, at 30?C using the appropriate UV-spectroscopic method. In protic solvents the unsubsituted acid displayed higher reaction rates than the methyl-substituted one. The results in aprotic solvents showed quite the opposite, and the reaction rates were considerably lower. In order to explain the obtained results through solvent effects, reaction rate constants (k) of the examined acids were correlated using the total solvatochromic equation of the form: log k=logk0+s?*+a?+b?, where ?* is the measure of the solvent polarity, a represents the scale of the solvent hydrogen bond donor acidities (HBD) and b represents the scale of the solvent hydrogen bond acceptor basicities (HBA). The correlation of the kinetic data were carried out by means of multiple linear regression analysis and the opposite effects of aprotic solvents, as well as the difference in the influence of protic and aprotic solvents on the reaction of the two examined acids with DDM were discussed. The results presented in this paper for cyclohex-1-enylcarboxylic and 2-methylcyclohex-1-enylcarboxylic acids were compared with the kinetic data for benzoic acid obtained in the same chemical reaction, under the same experimental conditions.

Transient-Phase and Steady-State Kinetics for Enzyme Activation

1973 ◽  
Vol 51 (6) ◽  
pp. 806-814 ◽  
Author(s):  
Nasrat H. Hijazi ◽  
Keith J. Laidler
Keyword(s):  
Steady State ◽  
Kinetic Data ◽  
Enzyme Activation ◽  
Transient Phase ◽  
Time Curve ◽  
Substrate Complex ◽  
Enzyme Substrate ◽  
Substrate Activation ◽  
Steady State Kinetics ◽  
Special Case

A non-steady-state analysis has been worked out for two mechanisms in which an activator Q can become attached to an enzyme–substrate complex EA, the species EAQ breaking down more rapidly than EA. It is shown that if EAQ breaks down into EQ + product there can be no steady state. If, however, EAQ breaks down into E + Q + product, the transient phase is followed by a steady state in which the product versus time curve is linear. A special case of this mechanism is when Q is the substrate (substrate activation). Some published kinetic data on carboxypeptidase are analyzed with reference to the equations derived.

Calibration of glucose biosensors by using pre-steady state kinetic data

1998 ◽  
Vol 13 (7-8) ◽  
pp. 801-807 ◽  
Author(s):  
Toonika Rinken ◽  
Ago Rinken ◽  
Toomas Tenno ◽  
Jaak Järv
Keyword(s):  
Steady State ◽  
Kinetic Data ◽  
Glucose Biosensors ◽  
Steady State Kinetic ◽  
State Kinetic

scholarly journals Effects of solvent and structure on the reactivity of 2-substituted nicotinic acids with diazodiphenylmethane in aprotic solvents

2012 ◽  
Vol 77 (5) ◽  
pp. 569-579
Author(s):  
Sasa Drmanic ◽  
Jasmina Nikolic ◽  
Bratislav Jovanovic
Keyword(s):  
Rate Constants ◽  
Substituent Effect ◽  
Kinetic Data ◽  
Reaction Rate ◽  
Linear Regression Analysis ◽  
Multiple Linear Regression Analysis ◽  
Aprotic Solvents ◽  
Solvent Interaction ◽  
Complete Form ◽  
Solute Solvent Interaction

The rate constants for the reactions of diazodiphenylmethane (DDM) with 2-substituted nicotinic acids in nine aprotic solvents at 30?C were determined. The obtained second order rate constants in aprotic solvents were correlated using the Kamlet?Taft solvatochromic equation in the complete form: log k = log k0 + s?* + a??+ b?. The correlations of the kinetic data were realized by means of multiple linear regression analysis. The obtained results were analyzed in terms of the initial and the transition state of the reaction and compared with previously determined kinetic data for nicotinic acid. The signs of the equation coefficients (s, a and b) are in agreement with the reaction mechanism and the influence of the solvent on the reaction rate is discussed based on the correlation results. The mode of the transmission of the substituent effect is discussed in light of the contribution of solute?solvent interaction to the reactivity of the acid. The substituent effect was additionally analyzed by the Hammett equation, log k = p??+ log k0.

Significance test of refractive index of solvent in evaluation of effect of medium on rates of quaternization reactions of methyl iodide with amines

1990 ◽  
Vol 55 (1) ◽  
pp. 180-184 ◽  
Author(s):  
Taťjana Nevěčná ◽  
Vojtěch Bekárek
Keyword(s):  
Refractive Index ◽  
Methyl Iodide ◽  
Rate Constants ◽  
Relative Permittivity ◽  
Significant Contribution ◽  
Activation Enthalpy ◽  
Dipole Moments ◽  
Significance Test ◽  
Activation Entropy ◽  
Aprotic Solvents

The rate constants have been measured of the reactions of methyl iodide with triethylamine (I) and tributylamine (III) at 293 K in twelve aprotic solvents, methyl iodide with tripropylamine (II) at 293, 313, 323, and 333 K in fifteen solvents differing greatly in their dipole moments, relative permittivities, and refractive indexes, and diiodomethane with tripropylamine in diiodomethane at 293 K (k1 = 2.1 10-5 s-1). The aprotic solvents predominantly affect the activation entropy which for the reaction of II varies from -200 J mol-1 s-1 (in cyclohexane) to -108 J mol-1 s-1 (in diiodomethane). The activation enthalpy of the reaction of methyl iodide with tripropylamine (II) is only little affected by aprotic solvents, a significant increase in activation enthalpy has been observed in the case of amphiprotic solvents. The evaluation of effect of medium on the rate constants of the above-mentioned reactions by means of the Kirkwood functions of relative permittivity and refractive index has shown a significant contribution of the refractive index of solvent which is comparable with the effect of relative permittivity.

scholarly journals Microhydration Effects on the Intermediates of the SN2 Reaction of Iodide Anion with Methyl Iodide

2013 ◽  
Vol 52 (16) ◽  
pp. 4380-4383 ◽  
Author(s):  
Keisuke Doi ◽  
Eijiro Togano ◽  
Sotiris S. Xantheas ◽  
Ryuzo Nakanishi ◽  
Takashi Nagata ◽  
...  
Keyword(s):  
Methyl Iodide ◽  
Iodide Anion ◽  
Sn2 Reaction
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