Aromatic Substitutions with Carbanion Nucleophiles. II. The Kinetics and Mechanism of the Reaction of 1-Fluoro-2,4-dinitrobenzene with the Diethyl Malonate Anion

1973 ◽  
Vol 51 (10) ◽  
pp. 1659-1664 ◽  
Author(s):  
Kenneth T. Leffek ◽  
Paul H. Tremaine
Keyword(s):  
Dimethyl Sulfoxide ◽  
Sodium Salt ◽  
Rate Constants ◽  
Activation Parameters ◽  
Diethyl Malonate ◽  
Kinetics And Mechanism ◽  
Reaction Solution ◽  
Red Color ◽  
Unstable Intermediate ◽  
Mechanism Of The Reaction

The reaction of fluoro-2,4-dinitrobenzene with the sodium salt of diethyl malonate to form diethyl (2,4-dinitrophenyl)malonate is fast in dimethyl sulfoxide solvent. The stable red color of the reaction solution is due to the anion of the product, although the initially formed unstable intermediate between the substrate and the anion nucleophile is also red and can be observed at times less than 200 ms after mixing.The rate constants for all the steps in the reaction have been measured and the activation parameters for the three processes involved in the nucleophile substitution have been calculated.

The kinetics and mechanism of the reaction between nickel(II) and dithiocarbamate ions in dimethyl sulfoxide. Evidence for the ID mechanism for a bidentate uninegative ligand

1978 ◽  
Vol 31 (12) ◽  
pp. 2581 ◽  
Author(s):  
PJ Nichols ◽  
MW Grant
Keyword(s):  
Fourier Transform ◽  
Ionic Strength ◽  
Dimethyl Sulfoxide ◽  
Excellent Agreement ◽  
Rate Constants ◽  
Second Order ◽  
Kinetics And Mechanism ◽  
First Order ◽  
Temperature Dependences ◽  
Mechanism Of The Reaction

13C Fourier-transform N.M.R. has been used to measure the rate of exchange of dimethyl sulfoxide with hexakis(dimethyl sulfoxide)nickel(II) cation. The parameters obtained, kex(25°C)(9.8�4.6) × 103 s-1, ΔH‡ 50�2 kJ mol-1 and ΔS‡ 0�4 J K-1 mol-1, are in excellent agreement with those of the most recent 1H N.M.R. study. The reaction between Ni(Me2SO)62+ and diethyldithiocarbamate (dtc-) gives only Ni(dtc)2. When dtc- is in excess, the rate of formation of Ni(dtc)2 is first order in Ni2+ and dtc-. The ionic-strength and temperature dependences of the second-order rate constants are consistent with the rate-determining formation of an unstable Ni(dtc)+ complex by an ID mechanism.

Kinetics and mechanism of the reaction of iron(III) with 6-methyl-2,4-heptanedione and 3,5-heptanedione

1990 ◽  
Vol 55 (8) ◽  
pp. 1984-1990 ◽  
Author(s):  
José M. Hernando ◽  
Olimpio Montero ◽  
Carlos Blanco
Keyword(s):  
Aqueous Solution ◽  
Metal Ion ◽  
Activation Parameters ◽  
Enol Form ◽  
Kinetics And Mechanism ◽  
Kinetic Constants ◽  
Steric Factors ◽  
Kinetics Of ◽  
Mechanism Of The Reaction

The kinetics of the reactions of iron(III) with 6-methyl-2,4-heptanedione and 3,5-heptanedione to form the corresponding monocomplexes have been studied spectrophotometrically in the range 5 °C to 16 °C at I 25 mol l-1 in aqueous solution. In the proposed mechanism for the two complexes, the enol form reacts with the metal ion by parallel acid-independent and inverse-acid paths. The kinetic constants for both pathways have been calculated at five temperatures. Activation parameters have also been calculated. The results are consistent with an associative activation for Fe(H2O)63+ and dissociative activation for Fe(H2O)5(OH)2+. The differences in the results for the complexes of heptanediones studied are interpreted in terms of steric factors.

The kinetics, isotope effects, and mechanism of the reaction of 2,2-di(4-nitrophenyl)-1,1,1-trifluoroethane with alkoxide bases in alcohol solvents

1985 ◽  
Vol 63 (3) ◽  
pp. 576-580 ◽  
Author(s):  
Arnold Jarczewski ◽  
Grzegorz Schroeder ◽  
Wlodzimierz Galezowski ◽  
Kenneth T. Leffek ◽  
Urszula Maciejewska
Keyword(s):  
Rate Constants ◽  
Isotope Effects ◽  
Activation Parameters ◽  
Tert Butanol ◽  
Deuterium Isotope Effects ◽  
Alcohol Solvents ◽  
Multistep Reaction ◽  
Mechanism Of The Reaction

The reaction between 2,2-di(4-nitrophenyl)-1,1,1-trifluoroethane and the alkoxide bases ŌCH3, ŌC2H5, ŌnC4H9, ŌCH(CH3)2, and ŌC(CH3)3 in their corresponding alcohol solvents is a multistep reaction with several intermediates: 2,2-di(4-nitrophenyl)-1,1-difluoro-1-alkoxyethane (A), 2,2-di(4-nitrophenyl)-1-fluoro-1-alkoxyethene (B), 2,2-di(4-nitrophenyl)-1,1-dialkoxyethene (C), 2,2-di(4-nitrophenyl)-1,1-difluoroethene (D), and 4,4′-dinitrobenzophene (E). Rate constants and activation parameters have been measured for the appearance of the two stable products B and C. The kinetic deuterium isotope effects for the appearance of B fell in the range of kH/kD = 1 to 2 at 25 °C for the primary and secondary alkoxides, whereas kH/kD = 5.4 at 30 °C for the appearance of D with tert-butoxide. Exchange experiments showed that H/D exchange took place between the substrate and solvent to the extent of 100% with methoxide, 50% with ethoxide and isopropoxide, and 0% with tert-butoxide. It is concluded the HF elimination from the substrate follows an (ElcB)R mechanism with methoxide/methanol, changing to (ElcB)I or E2 with tert-butoxide/tert-butanol.

Kinetics and Mechanism of the Reaction of Dichlorotetraaquaruthenium(III) and Thiols

2012 ◽  
Vol 65 (2) ◽  
pp. 113 ◽  
Author(s):  
Suprava Nayak ◽  
Gouri Sankhar Brahma ◽  
K. Venugopal Reddy
Keyword(s):  
Electron Transfer ◽  
Ionic Strength ◽  
Equilibrium Constants ◽  
Activation Parameters ◽  
Kinetics And Mechanism ◽  
Intermediate Complex ◽  
Mechanism Of Formation ◽  
Temperature Range ◽  
Temperature Reduction ◽  
Mechanism Of The Reaction

The formation of an intermediate ruthenium(iii) thiolate complex by the interaction of thiols, RSH (R = glutathione and l-cysteine) and dichlorotetraaquaruthenium(iii), [RuIIICl2(H2O)4]+, is reported in the temperature range 25–40°C. The kinetics and mechanism of formation of the intermediate complex were studied as a function of [RuIIICl2(H2O)4]+, [RSH], pH, ionic strength and temperature. Reduction of the intermediate complex takes place slowly and results in the corresponding disulfides RSSR and [RuIICl2(H2O)4]+. The results are interpreted in terms of a mechanism involving a rate-determining inner-sphere one-electron transfer from RSH to the oxidant used in the present investigation and a comparison of rate and equilibrium constants is presented with activation parameters.

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.

Aromatic substitutions with carbanion nucleophiles. IV. The kinetics and mechanism of the reaction of picryl bromide with diethylmalonate anion

1977 ◽  
Vol 55 (14) ◽  
pp. 2664-2669 ◽  
Author(s):  
Kenneth T. Leffek ◽  
Anna E. Matinopoulos-Scordou
Keyword(s):  
Equilibrium Constant ◽  
Rate Constants ◽  
Activation Parameters ◽  
Solvent System ◽  
Stopped Flow ◽  
Substitution Product ◽  
Picryl Chloride ◽  
Uv Visible ◽  
The Individual ◽  
Mechanism Of The Reaction

The reaction of picryl bromide with sodium diethylmalonate has been studied in benzene–DMSO 7:1 v/v by means of stopped-flow and uv–visible spectrophotometers. A Meisenheimer-like intermediate was detected, decomposing to yield the stable violet anion of the substitution product. The rate constants of the individual steps have been measured and the activation parameters calculated. Comparison with those obtained for picryl chloride support a bimolecular substitution via the 1,1-complex. The reaction with 1,3,5-trinitrobenzene is too fast to be measured in the same solvent system. The equilibrium constant is estimated to be of the order of 104–105.

Kinetics and mechanism of the reaction of cyanocobalamin with potassium hydroxide in non-aqueous media

2019 ◽  
Vol 43 (20) ◽  
pp. 7708-7715
Author(s):  
D. S. Salnikov ◽  
S. V. Makarov
Keyword(s):  
Dimethyl Sulfoxide ◽  
Potassium Hydroxide ◽  
Isopropyl Alcohol ◽  
Aqueous Media ◽  
Kinetics And Mechanism ◽  
Anaerobic Conditions ◽  
Mechanism Of The Reaction

The reaction of cyanocobalamin (CNCbl) with potassium hydroxide (KOH) was studied in isopropyl alcohol (iPrOH) and dimethyl sulfoxide (DMSO) under anaerobic conditions.

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