STUDIES IN THE WAGNER–MEERWEIN REARRANGEMENT: PART V. RATES OF FORMOLYSIS OF SOME 9-ALKYL-9-FLUORENYLMETHYL TOSYLATES

1965 ◽  
Vol 43 (9) ◽  
pp. 2465-2467 ◽  
Author(s):  
F. A. L. Anet ◽  
P. M. G. Bavin
Keyword(s):  
Formic Acid ◽  
Rate Constants ◽  
Alkyl Group

For a series of 9-alkyl-9-fluorenylmethyl p-toluenesulfonates, the rates of decomposition in formic acid increase with the size of the alkyl group. Changes in the rate constants are associated with changes in ΔS≠.

Catalysis by α-cyclodextrin of the reaction of formic acid with bromine

1990 ◽  
Vol 68 (11) ◽  
pp. 2119-2121 ◽  
Author(s):  
Oswald S. Tee ◽  
Bushra Javed ◽  
Susan R. Mikkelsen
Keyword(s):  
Formic Acid ◽  
Dissociation Constant ◽  
Rate Constants ◽  
Reaction Conditions ◽  
Value Analysis ◽  
Potentiometric Measurements

α-Cyclodextrin (CD) modestly increases the rate of oxidation of formic acid by bromine. The variation of rate constants with [Br−] is consistent with dominance of the formation of a CD•Br3− complex in determining the fraction of free Br2 and the CD•Br2 complex, under the reaction conditions. Potentiometric measurements support a dissociation constant of about 0.2 mM for the CD•Br3− complex, in agreement with an earlier spectrophotometric value. Analysis of the rate increases with [CD] implies that CD•Br2 is more reactive (~10 times) than free Br2 towards formate ion, as was found for phenols. These conclusions differ from those of another recent study. Keywords: catalysis, α-cyclodextrin, oxidation, formic acid, bromine.

Reaction of Dihydroxymethyl Radical with Molecular Oxygen in Aqueous Solution

1980 ◽  
Vol 35 (8) ◽  
pp. 1035-1039 ◽  
Author(s):  
Eberhard Bothe ◽  
Dietrich Schulte-Frohlinde
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Peroxide ◽  
Formic Acid ◽  
Molecular Oxygen ◽  
Rate Constants ◽  
Oxygen Diffusion ◽  
Bimolecular Reaction ◽  
Dose Rates ◽  
A Value ◽  
Diffusion Controlled

Abstract Dihydroxymethyl radical (1) was found to react with oxygen diffusion controlled (k = 4.5 x 109 M-1 s-1). The final products of the reaction are formic acid and 1/2 hydrogen peroxide. The precursor of H2O2 was shown to be O2·- which is formed with G(O2·-) = 6.3 (a value which includes the O2·- formed by H atoms and oxygen (G(H) = 0.55)). If it is assumed that dihydroxymethylperoxyl radicals are formed as intermediates the rate constant of O2·- formation must be ≥ 106 s-1 . A bimolecular reaction of two dihydroxy-methylperoxyl radicals forming tetroxides does not occur at the dose rates used. The rate constants for the establishment of the equilibriumhave been determined at pH 5.7 and 19 °C to be k3=1.9x 10-2 M-1 s-1 and k-3 = 1.5 X 10-6 M-1 s-1 in aqueous solution.

The reaction of some nuclear substituted acyclic conjugated styryl ketones and related Mannich bases with ethanethiol

1980 ◽  
Vol 58 (10) ◽  
pp. 984-991 ◽  
Author(s):  
J. R. Dimmock ◽  
L. M. Smith ◽  
P. J. Smith
Keyword(s):  
Rate Constants ◽  
Alkyl Group ◽  
Mannich Bases ◽  
Second Order ◽  
Reaction Intermediates ◽  
Aqueous Acetonitrile ◽  
Alkyl Groups ◽  
Inductive Effects ◽  
The Stability ◽  
Carbonyl Function

The second order rate constants for the reaction of ethanethiol with a number of conjugated nuclear-substituted styryl ketones and related Mannich bases in 50% aqueous acetonitrile was undertaken. Variation of the alkyl group adjacent to the carbonyl function was accompanied by altered avidity to ethanethiol which was explained as being due in part to the varying inductive effects of the alkyl groups which would, in turn, affect the stability of the reaction intermediates. The greatest disparity in reactivity between groups of compounds was between the ketones and analogous Mannich bases which was in accord with the marked difference in bioactivities between these two groups of compounds.

The syn-anti dichotomy in bimolecular elimination of alkyltrimethylammonium salts: Steric and polar effects on rates and orientation in the competing pathways

1979 ◽  
Vol 44 (4) ◽  
pp. 1273-1295
Author(s):  
Jiří Závada ◽  
Magdalena Pánková
Keyword(s):  
Rate Constants ◽  
Homologous Series ◽  
Alkyl Group ◽  
Complex Reaction ◽  
Potassium Methoxide ◽  
Title Problem ◽  
Structure Reactivity Relationship ◽  
The Individual ◽  
Standing Question ◽  
Competing Pathways

The title problem has been investigated in two homologous series of positionally isomeric alkyltrimethylammonium salts, RCH2CHXC5H11 and RCHXCH2C5H11 (R = H, CH3, C2H5, n-C3H7, iso-C3H7 and tert-C4H9; X = N(+)(CH3)3Cl)(-), employing potassium tert-butoxide in tert-butanol and also potassium methoxide in methanol as the base-solvent combination. The overall rate constants of the individual olefin-isomer formation have been determined in these series and dissected, approximately, into the syn- and anti-components. The alkyl structure-reactivity relationship is thus obtained separately for the two complementary mechanisms of bimolecular elimination. The long-standing question whether steric or polar influence of alkyl group dominates in the complex reaction is re-examined on these grounds. Contrary to earlier extreme views it is shown that both the steric as well as the polar effects are very important, the former being operative mainly in the stereochemical (syn-anti) whereas the latter in the orientational (Hofmann-Saytzeff) control of the dichotomous reaction.

scholarly journals Investigation of the reactivity of 4-pyrimidinecarboxylic, 6-hydroxy-4-pyrimidinecarboxylic and 5-hydroxyorotic acids with diazodiphenylmethane in various alcohols: Part III

2007 ◽  
Vol 72 (3) ◽  
pp. 205-214 ◽  
Author(s):  
Fathi Assaleh ◽  
Aleksandar Marinkovic ◽  
Sasa Drmanic ◽  
Bratislav Jovanovic
Keyword(s):  
Solvent Effects ◽  
Spectrophotometric Method ◽  
Rate Constants ◽  
Alkyl Group ◽  
Relative Permittivity ◽  
Reaction Rate ◽  
Hydrogen Atoms ◽  
Protic Solvents ◽  
Hydroxybenzoic Acids ◽  
Polar Constant

Rate constants for the reaction of diazodiphenylmethane (DDM) with 4-pyrimidinecarboxylic, 6-hydroxy-4-pyrimidinecarboxylic and 5-hydroxyorotic acids were determined in twelve protic solvents at 30 ?C using the well known UV-spectrophotometric method. The second order rate contants for the examined acids were correlated using the appropriate solvent parameters by the equation log k = log k0 + af(e) + bs * + cngH were f(e) is the Kirkwood function of relative permittivity [(e-l)/(2e + 1 )], s * is the Taft polar constant for the alkyl group R in the alcohol ROH, and nyH is themumber of hydrogen atoms in the (-position in the alcohol. The results obtained for the investigated acids were compared with the corresponding results for benzoic, 2- and 3-hydroxybenzoic acids and the influence of the structure of the investigated acids on the reactivity in hydroxylic solvents is discussed. It was also possible to evaluate and distinguish the specific and non-specific solvent effects and their influence on the reaction rate.

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