Effect of temperature on the ionization constants of some β-diketones

Taneja, A. D.; Rao, N. U. M.; Tiwari, H. P.; PRASAD, C. S. G.

doi:10.1016/0022-1902(74)80719-0

Cited by 2 publications

(2 citation statements)

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“…They also serve as model compounds for the investigation of intramolecular charge transfer dual fluorescence of p-dimethylaminobenzanilides [14] and N -benzoylaminonaphthalenes [15]. Acid dissociation constants of acetoacet-o-toluidide and similar compounds have been determined potentiometrically [16].…”

Section: Scheme 1 Protonation Equilibria Of the Benzotoluididesmentioning

confidence: 99%

Protonation acidity constants for benzotoluidides in sulfuric acid solutions

Stojković

Anastasova

2006

Open Chemistry

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Abstract:The protonation of o-, m-and p-benzotoluidide in sulfuric acid solutions is studied by UV spectroscopy in the 190-350 nm region. Principal component analysis is applied to estimate the contributions of the effect of protonation and the medium effect. For the substances studied in this work, the first principal component (PC) captures about 98 % of the variance and the second PC ∼100 % of the cumulative percentage variance in the 210-350 nm region. The same spectral region is used for calculation of the ionization ratio from the coefficients of the first PC and mole fractions of the base and its conjugate acid. Using these data and Hammett's equation (pK BH+ = H X + log I), the pK BH+ values for the protonation reaction are obtained. The dissociation constants as well as the solvent parameters m* (∼0.43) and φ (∼0.60) are calculated using the Excess Acidity Method (-pK BH+ = 2.28-2.30) and the BunnettOlsen Method (-pK BH+ = 2.24-2.28). The probable sites of protonation are discussed.

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Section: Scheme 1 Protonation Equilibria Of the Benzotoluididesmentioning

confidence: 99%

Protonation acidity constants for benzotoluidides in sulfuric acid solutions

Stojković

Anastasova

2006

Open Chemistry

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“…Heating N -(2‘,5‘dimethoxyphenyl)-3-oxobutanamide ( 14a ) with 1 in the presence of 1.1 equiv of sodium hydride and a catalytic amount of copper(II) acetate gave a mixture of the C 2 -monoarylated derivative 15a and the α-ketoanilide 16a (see below). This preference toward C -arylation cannot be attributed to a higher acidity of C-2 with respect to the nitrogen atom since the NH of β-ketoanilides is known to be more acidic than their methylene group . Steric hindrance on the nitrogen atom caused by the nearby C 2 ‘ -OCH 3 group might be an alternative explanation, but it was ruled out by the results obtained in a similar reaction of the monomethoxy derivative 14b , prepared from m -anisidine and 2,2,6-trimethyl-1,3-dioxin-4-one .…”

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confidence: 99%