Thep-pRelation and the Reaction oftrans-Cinnamic Acids with Diphenyldiazomethane The Basis of the Hammett Equation

1964 ◽  
Vol 86 (8) ◽  
pp. 1507-1512 ◽  
Author(s):  
Janet D. Sharp. Ritter ◽  
Sidney I. Miller
Keyword(s):  
Hammett Equation ◽  
Cinnamic Acids

Further studies an the extended Hammett equation comprising the hydrophobic constant: Reactivity data for benzoic acids, arylacetic acids, β-arylpropionic acids, trans- and cis-cinnamic acids, methyl benzoates; dissociation constants, DDM reaction and alkaline hydrolysis in various water-organic solvent mixtures

1990 ◽  
Vol 55 (1) ◽  
pp. 119-135 ◽  
Author(s):  
Anthonius J. Hoefnagel ◽  
Bartholomeus M. Wepster
Keyword(s):  
Organic Solvent ◽  
Alkaline Hydrolysis ◽  
Dissociation Constants ◽  
Solvent Mixtures ◽  
Benzoic Acids ◽  
Hammett Equation ◽  
Cinnamic Acids ◽  
Tert Butanol ◽  
Arylacetic Acids

The extended Hammett eguaition Δ = ρs + hπ comprising the hydrophobic constant π is found to be effective in the title compounds and reactivities in various solvent mixtures. In 32 vol.% tert-butanol-water hmdecreases in the order ArCOOMe (-0.25), cis-ArCH=CHCOOH (-0.18), ArCOOH and ArCH2COOH (-0.16), ArCH2CH2COOH and trans-ArCH=CHCOOH (-0.07). For ArCOOH, mixtures like 40-60% methanol, 50% ethanol, 50% acetone and 50% dioxane give similar hm values of circa -0.05. For ArCH2COOH the effects of 3-iodo and 4-iodo substituents are acid-weakening in 32% tert-butanol. The consequences of the hπ term for ρ, σ, and the averaging of σ values, are discussed.

The application of the Hammett equation to 13C N.M.R. spectrometry. II. Cβ resonances: a test of dual substituent parameter relationships

1977 ◽  
Vol 30 (8) ◽  
pp. 1715 ◽  
Author(s):  
DAR Happer ◽  
SM McKerrow ◽  
AL Wilkinson
Keyword(s):  
Hammett Equation ◽  
Cinnamic Acids ◽  
Better Than

Previous studies (Part I) have shown that the 13C resonance positions of the β-carbon of both meta- and para-substituted β-nitrostyrenes are well correlated by means of the Hammett equation if σ+ constants are used for para + R substituents. These data have now been supplemented with measurements made on five additional series: cinnamic acids, cinnamate ions, styrenes, β,β-dimethyl- and β,β-dicyano-styrenes. ��� The combined information has been analysed by means of three ?dual substituent parameter? versions of the Hammett equation. The results confirm that all three are only approximations, but that the Yukawa- Tsuno and Ehrenson-Brownlee-Taft relationships are significantly better than Swain's F/R treatment.

Anticancer Agents Derived from Natural Cinnamic Acids

2015 ◽  
Vol 15 (8) ◽  
pp. 980-987 ◽  
Author(s):  
Ping Su ◽  
Yaling Shi ◽  
Jinfeng Wang ◽  
Xiuxiu Shen ◽  
Jie Zhang
Keyword(s):  
Anticancer Agents ◽  
Cinnamic Acids

Solvolysis kinetics and mechanism of substituted 3-acetyl-1,3-diphenyltriazenes in acid medium; Kinetic acidity function

1987 ◽  
Vol 52 (9) ◽  
pp. 2212-2216
Author(s):  
Oldřich Pytela ◽  
Martin Kaska ◽  
Miroslav Ludwig ◽  
Miroslav Večeřa
Keyword(s):  
Acid Medium ◽  
Sulphuric Acid ◽  
Rate Constants ◽  
Decomposition Kinetics ◽  
Acidity Function ◽  
Hammett Equation ◽  
Kinetic Acidity ◽  
Reaction Constant ◽  
Acid Catalyzed ◽  
Catalytic Rate

The decomposition kinetics has been measured of fourteen 3-acetyl-1,3-bis(subst. phenyl)triazenes in 40% (v/v) ethanol and sulphuric acid. The kinetic acidity function and catalytic rate constants have been determined from the rate constants observed. Mechanism has been suggested for the general acid-catalyzed solvolysis from comparison of the course of the kinetic acidity function and H0 function and from the reaction constant of the Hammett equation.

Kinetics and Mechanism of Decomposition of 1,3-Bis(4-methylphenyl)triazene Catalyzed with Substituted Benzoic Acids in 25% Aqueous Methanol-General or Specific Catalysis?

1994 ◽  
Vol 59 (9) ◽  
pp. 2029-2041
Author(s):  
Oldřich Pytela ◽  
Taťjana Nevěčná
Keyword(s):  
Benzoic Acids ◽  
Hammett Equation ◽  
Aqueous Methanol ◽  
Mechanism Of Decomposition ◽  
Kinetics Of Decomposition ◽  
Independent Variable ◽  
Amino Derivatives ◽  
Substituted Benzoic Acids ◽  
The Individual ◽  
Kinetics Of

The kinetics of decomposition of 1,3-bis(4-methylphenyl)triazene catalyzed with 13 substituted benzoic acids of various concentrations have been measured in 25 vol.% aqueous methanol at 25.0 °C. The rate constants observed (297 data) have be used as values of independent variable in a series of models of the catalyzed decomposition. For the catalytic particles were considered the undissociated acid, its conjugated base, and the proton in both the specific and general catalyses. Some models presumed formation of reactive or nonreactive complexes of the individual reactants. The substituent effect is described by the Hammett equation. The statistically best model in which the observed rate constant is a superposition of a term describing the dependence on proton concentration and a term describing the dependence on the product of concentrations of proton and conjugated base is valid with the presumption of complete proton transfer from the catalyst acid to substrate, which has been proved. The behaviour of 4-dimethylamino, 4-amino, and 3-amino derivatives is anomalous (lower catalytic activity as compared with benzoic acid). This supports the presumed participation of conjugated base in the title process.

Syringic and cinnamic acids antiradical/antioxidant activities as R. ferruginea extract components and membrane physico-chemical influence

2020 ◽  
Vol 1220 ◽  
pp. 128749
Author(s):  
Desirée Magalhães dos Santos ◽  
Mariele Paludetto Sanches ◽  
Claudio Michel Poffo ◽  
Alexandre Luís Parize ◽  
Gabriel Jorge Sagrera Darelli ◽  
...  
Keyword(s):  
Antioxidant Activities ◽  
Cinnamic Acids ◽  
Physico Chemical ◽  
Chemical Influence

Substituent effects on the thermodynamic functions of ionization of metasubstituted anilinium ions

1968 ◽  
Vol 21 (4) ◽  
pp. 939 ◽  
Author(s):  
PD Bolton ◽  
FM Hall
Keyword(s):  
Linear Function ◽  
Thermodynamic Functions ◽  
Substituent Effects ◽  
Negative Slope ◽  
Hammett Equation ◽  
Reaction Parameter ◽  
Reaction Series ◽  
Acidity Constants ◽  
Temperature Range ◽  
Relationship Of

Thermodynamic acidity constants of the meta-methoxyanilinium, meta- chloroanilinium, meta-bromoanilinium, and meta-iodoanilinium ions have been measured spectrophotometrically over the temperature range 5-50� and those of the meta-nitroanilinium ion over the temperature range 5-60�. The thermodynamic functions of ionization, ΔG25, ΔH25, ΔS25, and ΔCp,25, have also been calculated for each ion. For a series of seven meta-substituted anilinium ions the acidity constants show close obedience to the Hammett equation over the temperature range 10-50� with the reaction parameter p being a precise linear function of 1/T. The same reaction series also shows a well-defined isoequilibrium relationship of negative slope.

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