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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.

In the title compound (5‐fluoro­isatin), C8H4FNO2, the N atom of one mol­ecule is linked to the amido‐O atom of an adjacent mol­ecule across a center of symmetry by a cyclic hydrogen bond [N⃛O = 2.888 (4) Å].

A novel synthetic methodology for preparation of thiocarbohydrazone by reacting thiocarbohydrazide with 1-acetyl-5-chloroisatin is described. The title compound was prepared by condensation of thiocarbohydrazide and substituted isatin in aqueous ethanol. The newly synthesized compound was characterized using 1H-NMR, 13C-NMR, FT-IR and mass spectrometry

Key indicatorsSingle-crystal X-ray study T = 295 K Mean (C-C) = 0.004 Å R factor = 0.058 wR factor = 0.153 Data-to-parameter ratio = 17.1 For details of how these key indicators were automatically derived from the article, see