The Pseudo Thermodynamics of Solvolysis. A Detailed Study of the Pressure and Temperature Dependence of Benzyl Chloride Solvolysis in t-Butyl Alcohol – Water Mixtures

1971 ◽  
Vol 49 (14) ◽  
pp. 2394-2405 ◽  
Author(s):  
S. J. Dickson ◽  
J. B. Hyne
Keyword(s):  
Benzyl Chloride ◽  
Activation Parameters ◽  
Butyl Alcohol ◽  
Second Derivative ◽  
Classical Thermodynamic ◽  
Structure Variation ◽  
First Order ◽  
Alcohol Water ◽  
Aqueous Solvent ◽  
Pseudo First Order

The pseudo first order rate constants for the solvolysis of benzyl chloride in aqueous t-butyl alcohol (t-BuOH) are reported at 40.00, 50.25, and 60.50 °C at various pressures up to 4084 atm. From these data the first temperature derivatives (ΔH* and ΔS*), the first (ΔV*) and second pressure derivatives, ∂ΔV*/∂P, and the mixed second derivative, ∂ΔV0*/∂T, of the rate are evaluated. These activation parameters exhibit extremum behavior in the highly aqueous solvent region. This behavior is discussed in terms of solvent structure variation. The signs of the pressure dependence of ΔH* and ΔS* are shown to be consistent with those required by the Maxwell type relationships for classical thermodynamic systems.

scholarly journals Kinetics and Oxidation of Substituted Benzyl Alcohols by Phenyliodoso Acetate

2011 ◽  
Vol 8 (1) ◽  
pp. 264-268
Author(s):  
R. Girija ◽  
S. Aruna
Keyword(s):  
Correlation Analysis ◽  
Benzyl Alcohol ◽  
Activation Parameters ◽  
Butyl Alcohol ◽  
Water Medium ◽  
Rate Data ◽  
Benzyl Alcohols ◽  
First Order ◽  
Alcohol Water ◽  
Different Temperatures

Oxidation of benzyl alcohol and somemeta- andpara- substituted alcohols by phenyliodoso acetate (PIA) int-butyl alcohol–water medium (50:50) leads to the formation of corresponding benzaldehyde. The stoichiometry of the reaction was found to be 1:1. The reaction was first order each in substrate and oxidant concentrations. This reaction was studied at four different temperatures and the activation parameters were calculated. Correlation analysis was carried out using Taft’s and Swain’s dual substituent parameter (DSP) equation. The rate data ofmeta- compounds showed good correlation with (F,R) values,para-substituted benzyl alcohols showed good correlation with σIσR+A suitable mechanism has been proposed.

Kinetics and Activation Parameters for the Alkaline Aqueous Rearrangement of Trichorfon [O,O-Dimethyl-(2,2,2-Trichloro-1-Hydroxyethyl) Phosphonate] to Dichlorvos [O,O-Dimethyl-O-(2,2-Dichloroethenyl)Phosphate]

2001 ◽  
Vol 36 (3) ◽  
pp. 589-604 ◽  
Author(s):  
Julian M. Dust ◽  
Christopher S. Warren
Keyword(s):  
Activation Energy ◽  
High Pressure ◽  
Activation Parameters ◽  
Base Catalysis ◽  
Rearrangement Product ◽  
Exponential Factor ◽  
First Order ◽  
Pseudo First Order ◽  
Order Plot ◽  
Kinetics Of

Abstract The kinetics of the alkaline rearrangement of O,O-dimethyl-(2,2,2-trichloro-1- hydroxyethyl)phosphonate, (trichlorfon, 1), the active insecticidal component in such formulations as Dylox, was followed at 25±0.5°C by high pressure liquid chromatography (UV-vis detector, 210 nm). The rearrangement product, O,Odimethyl- O-(2,2-dichloroethenyl)phosphate (dichlorovos, 2), which is a more potent biocide than trichlorfon, undergoes further reaction, and the kinetics, consequently, cannot be treated by a standard pseudo-first-order plot. A two-point van't Hoff (initial rates) method was used to obtain pseudo-first-order rate constants (kѱ) at 25, 35 and 45°C: 2.6 × 10-6, 7.4 × 10-6 and 2.5 × 10-5 s-1, respectively. Arrhenius treatment of this data gave an activation energy (Ea) of 88 kJ·mol-1 with a pre-exponential factor (A) of 5.5 × 109 s-1. Kinetic trials at pH 8.0 using phosphate and tris buffer systems show no buffer catalysis in this reaction and indicate that the rearrangement is subject to specific base catalysis. Estimates are reported for pseudo-first-order half-lives for trichlorfon at pH 8.0 for environmental conditions in aqueous systems in the Corner Brook region of western Newfoundland, part of the site of a recent trichlorfon aerial spray program.

Electron-Transfer Reactions in Non-Aqueous Media. V. Solvent Effects in the Reduction of CoN3(NH3)52+ by Iron(II)

1979 ◽  
Vol 32 (10) ◽  
pp. 2139 ◽  
Author(s):  
TJ Westcott ◽  
DW Watts
Keyword(s):  
Electron Transfer ◽  
Aqueous Media ◽  
Activation Parameters ◽  
Transfer Reactions ◽  
Tetrahedral Coordination ◽  
First Order ◽  
Precursor Complex ◽  
Stage Process ◽  
Pseudo First Order ◽  
Reversible Formation

The reduction of CoN3(NH3)52+ by iron(II) is rate-determined by a two-stage process involving the reversible formation of an azide-bridged precursor complex prior to electron transfer in each of the solvents water, Me2SO, aqueous Me2SO and HCONMe2. The activation parameters in H2O and Me2SO, and the trends shown with increasing Me2SO concentrations in aqueous Me2SO, are similar to the properties of the previously studied CoCl(NH3)52+ and CoBr(NH3)52+ systems and contrast with the reduction of COF(NH3)52+. The results are consistent with a bridged precursor complex octahedral at both the iron and cobalt atoms in water but with tetrahedral coordination about the iron in Me2SO. In HCONMe2, as in the reduction of COF(NH3)52+, COCl(NH3)52+ and COBr(NH3)52+, the precursor complex is a significant part of the reacting solutions, and as a result the experimental pseudo-first-order rate constants for the loss of CoIII are not linearly dependent on the concentration of FeII. The initial spectra of the reacting solutions in this system also indicate significant concentrations of the precursor complex.

Kinetics and mechanism of aminolysis of (Z)-4-arylidene-2-phenyl-5(4H)oxazolones

1992 ◽  
Vol 70 (10) ◽  
pp. 2515-2519 ◽  
Author(s):  
Sharifa S. Alkaabi ◽  
Ahmad S. Shawali
Keyword(s):  
Rate Constants ◽  
Activation Parameters ◽  
Order Conditions ◽  
Kinetics And Mechanism ◽  
Hammett Equation ◽  
Third Order ◽  
First Order ◽  
Different Temperatures ◽  
Pseudo First Order ◽  
Kinetics Of

The kinetics of the reactions of a series of (Z)-4-arylidene-2-phenyl-5(4H)oxazolones 1 with n-butylamine and piperidine were studied spectrophotometrically in dioxane, ethanol, and cyclohexane under pseudo-first-order conditions and at different temperatures. The relation k1(obs) = k2[amine] + k3[amine]2 was found applicable for all reactions studied in either dioxane or ethanol. However, in cyclohexane the n-butylaminolysis of 1 followed only third-order kinetics k1(obs) = k3[n-BuNH2]2. The kinetics of the reaction of 1 with n-butylamine in the presence of catalytic amounts of triethylamine in dioxane followed the equation: k1(obs)k2 = [n-BuNH2] + k3[n-BuNH2]2[Formula: see text] [Et3N]. The rate constants k2 and k3 correlated well with the Hammett equation and the corresponding activation parameters were determined. The results were interpreted in terms of a mechanism involving solvent- and amine-catalyzed processes.

Kinetics of oxidation of the bis(ethylenediamine)mercaptoacetatocobalt(III) and cysteinato-bis(ethylenediamine)cobalt(III) ions by hydrogen peroxide in mixed aqueous-nonaqueous solutions

1988 ◽  
Vol 53 (3) ◽  
pp. 554-562
Author(s):  
Ján Benko ◽  
Oľga Vollárová ◽  
Miroslav Kovarčík
Keyword(s):  
Hydrogen Peroxide ◽  
Reaction Rate ◽  
Activation Parameters ◽  
Butyl Alcohol ◽  
Acid Base ◽  
Kinetics Of Oxidation ◽  
Tert Butyl Alcohol ◽  
Alcohol Water ◽  
Acid Base Equilibrium ◽  
Kinetics Of

The kinetics of oxidation of the coordinatively bonded sulphur in the cysteinato-bis(ethylenediamine)cobalt(III) and bis(ethylenediamine)mercaptoacetatocobalt(III) complexes by hydrogen peroxide to the sulphoxides was examined in HClO4 solutions (c(HClO4) = 1 – 500 mmol l-1) with a view to obtaining data characterizing the effect of the acid-base equilibria of the reactants on the reaction rate. The reaction rate was found affected particularly by the acid-base equilibrium of the oxidant, which plays a role in strongly acid solutions. The oxidation was also studied in water-methyl alcohol, water-tert-butyl alcohol and water-ethylene glycol mixtures, and the effect of the mole fraction of the nonaqueous component on the rate constant and thermodynamic activation parameters was examined.

scholarly journals Kinetic Isotope Effects in the Chromium(VI) Oxidation of Bicyclic Alcohols

1999 ◽  
Vol 23 (2) ◽  
pp. 146-147
Author(s):  
J. Hodge Markgraf ◽  
Jordan S. Dubow ◽  
Jessica A. Charland ◽  
Elliott H. Sohn
Keyword(s):  
Rate Constants ◽  
Acidic Solution ◽  
Isotope Effects ◽  
Activation Parameters ◽  
Kinetic Isotope Effects ◽  
Secondary Alcohols ◽  
First Order ◽  
Chromium Vi ◽  
Kinetic Isotope ◽  
Pseudo First Order

Pseudo first-order rate constants are determined for the oxidation of a series of secondary alcohols and their monodeutero analogues by ammonium chromate in aqueous acidic solution at several temperatures; the relative rates and activation parameters are consistent with a cyclic, symmetrical transition state.

Sterically Hindered Aromatic Compounds. V. Solvolysis of p-Methyl-, 2,4,6-Trimethyl-, and 2,4,6-Tri-t-butylbenzyl Chloride. Effect of Solvent and α-Deuterium Substitution

1972 ◽  
Vol 50 (24) ◽  
pp. 3965-3972 ◽  
Author(s):  
L. R. C. Barclay ◽  
J. R. Mercer ◽  
J. C. Hudson
Keyword(s):  
Chemical Shifts ◽  
Isotope Effects ◽  
Activation Parameters ◽  
Butyl Alcohol ◽  
Deuterium Isotope Effect ◽  
Limiting Behavior ◽  
Kinetic Isotope ◽  
Deuterium Substitution ◽  
Alcohol Water ◽  
Chloride Effect

Rates, activation parameters, and kinetic α-deuterium isotope effects are reported for solvolysis of p-methyl-benzyl chloride in 80% trifluoroethanol–water, and in ethanol–water and t-butyl alcohol–water of varying solvent compositions. The α-deuterium isotope effect in trifluoroethanol–water (kH/kD = 1.14 per D) indicates approximately limiting behavior. Results in the other solvents (kH/kD = 1.04–1.08) indicate considerable nucleophilic participation by solvent in the transition state. 2,4,6-Trimethylbenzyl chloride gave kH/kD = 1.09 in 80% ethanol–water but kH/kD = 1.16 in 80% trifluoroethanol–water. 2,4,6-Tri-t-butylbenzyl chloride showed kH/kD effects of 1.13–1.15 in t-butyl alcohol–water and 1.15–1.16 in ethanol–water. The higher kinetic isotope effects for solvolysis of these trialkylbenzyl chlorides are discussed in terms of steric hindrance to nucleophilic participation by solvent. N.m.r. chemical shifts give evidence for steric compression of the benzylic protons in 2,4,6-tri-t-butylbenzyl chlorides.

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