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Journal
2006 | 4 | 1 | 56-67
Article title

Protonation acidity constants for benzotoluidides in sulfuric acid solutions

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EN
Abstracts
EN
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 Bunnett-Olsen Method (-pK
BH
+= 2.24–2.28). The probable sites of protonation are discussed.
Publisher
Journal
Year
Volume
4
Issue
1
Pages
56-67
Physical description
Dates
published
1 - 3 - 2006
online
1 - 3 - 2006
References
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Document Type
Publication order reference
YADDA identifier
bwmeta1.element.-psjd-doi-10_1007_s11532-005-0004-y
Identifiers
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