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Crystal structure and spectroscopic properties of 4-acetaminopyridine and its protonated form

Koleva B.B., Nikolova R., Tchapkanov A., Kolev T., Mayer-Figge H., Spiteller M., Sheldrick W.S.

Polish Journal of Chemical Technology

2009

Vol. 11, nr 3

35-40

4-Acetaminopyridine dihydrate and its protonated form, stabilized as the hydrochloride salt have been synthesized and spectroscopic elucidated in solution and in the solid-state by means of the inear-polarized solid state IR-spectroscopy (IR-LD), UV-spectroscopy, TGA, DSC, and the positive and negative ESI MS. Quantum chemical calculations were used to obtain the electronic structure, vibrational data and the electronic spectra. The spectroscopic and theoretical data are compared with the structure of the first compound obtained by single crystal X-ray diffraction. The effect of Npy protonation on the optical and magnetic properties of a 4-acetaminopyridine is discussed.

Acidity of the N+Ch2 Protons in N-Phenacyl-R-pyridinium Bromides

Szafran M., Szwajca A.

Polish Journal of Chemistry

2004

Vol.78 /nr 11-12

2131-2140

UV-Vis, FTIR, 1H and 13C NMR and MS spectra of 19 N-phenacyl-R-pyridinium bromides and their ylides were measured and analysed. In crystals the investigated salts appear as keto-tautomer, but in water solutions in a keto-enol tautomeric equilibrium. In most salts, the N+CH2 hydrogens, undergo fast hydrogen-deuterium exchange in neutral D2O at room temperature, which confirms the presence of some amount of enolic tautomers in aqueous solutions. The intensity of the ylide bands in the 385-480 nm region is substituent and time dependent and reflects the rates of their formation and decomposition. The ylides with electron-withdrawing substituents form and decompose much faster than those with electron-donating ones.

Stability of 1-Phenacylpyridinium and 1-(2-Hydroxy-2-phenylvinyl)pyridinium Cations

Ośmiałowski B., Janota H., Gawinecki R.

Polish Journal of Chemistry

2003

Vol. 77 / nr 2

169-177

1H, 13C and 15N NMR Spectral and X-ray Structural Studies of 2-Arylsulfonylamino-5-chlorobenzophenones

Kolehmainen E., Nissinen M., Janota H., Gawinecki R., Ośmiałowski B.

Polish Journal of Chemistry

2003

Vol. 77 / nr 7

889-894

Six 2-(4-R-phenylsulfonylamino)-5-chlorobenzophenones were prepared and their 1H, 13Cand 15NNMRspectra recorded and assigned. The dependence between the chemical shift of the amide proton and Hammett _ substituent constants is of the V type. Substituent effect on the chemical shift of the amide nitrogen atom was found insignificant. X-ray analysis shows that the terminal benzene rings in 2-(4-nitrophenylsulfonylamino)-5-chlorobenzophenone are located close to each other. They are not, however, parallel, dihedral angle between them being equal to 10.86 deg (MP2/6-31G**//HF/6-31G** ab initio calculations show this to be 20.44 deg). This shows that the mutual orientation of two benzene rings in the molecule of this compound is caused by the _-_ stacking. It is additionally reinforced by the intramolecular NH…O=C hydrogen bond. Except the dihedral angle between the benzene rings, X-ray determined structure of 2-(4-nitrophenylsulfonylamino)-5-chlorobenzophenone is very similar to this optimized by the ab initio calculations.