<b>Experimental and theoretical NMR study of 4-(1-pyrrolidinyl)piperidine</b>

• Main Authors: Metin Bilge, Cemal Parlak, Özgür Alver
• Format: Article
• Language: English
• Published: Chemical Society of Ethiopia 2011-12-01
• Series: Bulletin of the Chemical Society of Ethiopia
• Subjects: 4-(1-Pyrrolidinyl)piperidine; NMR; DFT; Axial; Equatorial
• Online Access: http://ajol.info/index.php/bcse/article/view/68598

The possible stable forms and molecular structure of 4-(1-pyrrolidinyl)piperidine (4-pypp) have been studied experimentally and theoretically using nuclear magnetic resonance (NMR) spectroscopy. ¹H, ¹³C, ¹⁵N, DEPT, COSY and HETCOR NMR spectra of 4-pypp (C₉H₁₈N₂) have been reported. Solvent effects on nuclear magnetic shielding tensors have been investigated using chloroform-<i>d</i>, methanol-<i>d</i>, acetone-<i>d</i>, dimethylsulfoxide-<i>d</i> and water-<i>d</i>. The magnitude of ⁿJ(C,H) (n = 1, 2, 3) coupling constants of 4-pypp have been determined with selective ¹H decoupled ¹³C NMR techniques. ¹H, ¹³C, ¹⁵N NMR chemical shifts and ^1-3J(C,H) coupling constants have also been calculated for the most stable two conformers, equatorial-equatorial (e-e) and axial-equatorial (a-e) forms of 4-pypp using DFT/6-311++G(d,p)//6-31G(d) level of theory. Results from experimental and theoretical data have showed that the molecular geometry and the mole fractions of stable conformers of 4-pypp are solvent dependent.