Z. Dega‐Szafran, M. Jaskólski, I. Kurzyca
Sep 2, 2002
Citations
1
Influential Citations
27
Citations
Journal
Journal of Molecular Structure
Abstract
Abstract Two N,N′-dimethylpiperazine betaines (mono (3) and double (6)) have been synthesized. Betaine 3 reacts with two equivalents of HCl or HBr, while 6 only with one. In the crystal structure of N,N′-dicarboxymethyl-N,N′-dimethylpiperazine monohydrochloride (N,N′-dimethylpiperazine doublebetaine monohydrochloride, 7-Cl) determined by X-ray diffraction, the piperazinium moieties form infinite chains bridged by very strong, symmetrical and linear hydrogen bonds (O⋯O 2.460(2) A). The piperazine ring adopts a chair conformation with the CH2COOH group in the axial and the methyl group in the equatorial positions. The N+ atoms interact electrostatically with the Cl− ion and the oxygen atoms of the carboxylate groups. The FTIR spectrum of 7-Cl shows an intense broad absorption in the 1500–400 cm−1 region and a νCO band at 1734 cm−1. The pKa values of 3 and 6 were determined by potentiometric titration. The 1H and 13C NMR spectra in D2O were analyzed.