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An NMR investigation of the conformational equilibria of 2-(2'-pyridyl)ethylphosphonic acid in several solvents

Petterson, Krag A. and Fort, Diana and Wei, Peter D. and Roberts, John D. (2002) An NMR investigation of the conformational equilibria of 2-(2'-pyridyl)ethylphosphonic acid in several solvents. Chirality, 14 (2-3). pp. 204-208. ISSN 0899-0042. doi:10.1002/chir.10064.

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Vicinal proton–proton NMR couplings have been used to investigate whether the position of conformational equilibria is determined by intramolecular N-H hydrogen bonding for 2-(2′-pyridyl)ethylphosphonic acid 1 in its various possible ionization states in water, methanol, ethanol, and dimethyl sulfoxide (DMSO). With 1 in the form of its monoanion and dianion, the trans is favored, with the dianion being more trans than the monoanion for a given solvent, probably as the result of steric effects, possibly enhanced by repulsive electrostatic effects between the negatively charged phosphonic group and the lone pair on the pyridine nitrogen. For 1 and its conjugate acid, the gauche amounts, respectively, to 43% and 45% in water, 66% and 51% in methanol, 66% and 64% in ethanol, and 29% and 49% in DMSO. For these latter two species, electrostatic, steric, and hydrogen bonding-effects are all likely to play a role in determining the conformational equilibria.

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Additional Information:© 2002 Wiley-Liss, Inc. Received for publication 1 May 2001; Accepted 21 July 2001. Article first published online: 1 Feb 2002. Contract grant sponsors: The Petroleum Research Fund administered by the American Chemical Society the Summer Undergraduate Research Fellowship Program (SURF) at the California Institute of Technology the Camille and Henry Dreyfus Foundation the E. I. Du Pont de Nemours Company Dr. & Mrs. Chester M. McCloskey.
Funding AgencyGrant Number
American Chemical Society Petroleum Research FundUNSPECIFIED
Caltech Summer Undergraduate Research Fellowship (SURF)UNSPECIFIED
Camille and Henry Dreyfus FoundationUNSPECIFIED
E. I. du Pont de Nemours and CompanyUNSPECIFIED
Dr. and Mrs. Chester M. McCloskeyUNSPECIFIED
Subject Keywords: NMR coupling constants; NMR spectral analysis; rotamers; phosphonic acid strengths; hydrogen bonding by NMR
Issue or Number:2-3
Record Number:CaltechAUTHORS:20151001-101404150
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Official Citation:Petterson, K. A., Fort, D., Wei, P. D. and Roberts, J. D. (2002), An NMR investigation of the conformational equilibria of 2-(2′-pyridyl)ethylphosphonic acid in several solvents. Chirality, 14: 204–208. doi: 10.1002/chir.10064
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:60657
Deposited By: Ruth Sustaita
Deposited On:01 Oct 2015 22:00
Last Modified:10 Nov 2021 22:37

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