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Ionization equilibria of dicarboxylic acids in dimethyl sulfoxide as studied by NMR

Choi, Paul J. and Petterson, Krag A. and Roberts, John D. (2002) Ionization equilibria of dicarboxylic acids in dimethyl sulfoxide as studied by NMR. Journal of Physical Organic Chemistry, 15 (5). pp. 278-286. ISSN 0894-3230. doi:10.1002/poc.488.

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The ionization equilibria of dicarboxylic acids measured by K_1/K_2 are expected to be substantially influenced by stabilization of the monoanion through intramolecular hydrogen bonding. However, except in sterically favorable cases, such as with maleic, 3,4-furandicarboxylic, 2,3-bicyclo[1.2.2]heptadienedicarboxylic and diethylmalonic acids, the K_1/K_2 values for other dicarboxylic acids, where intramolecular hydrogen bonding of the monoanion might be expected, are relatively small at ∼100 in water. This research uses NMR to corroborate and extend the pioneering conductance measurements of K_1/K_2 of dicarboxylic acids by Kolthoff and coworkers with dimethyl sulfoxide (DMSO) as solvent. In extending these measurements, we have determined K_1/K_2 for 3,4-furandicarboxylic (1) and ,3-bicyclo[1.2.2]heptadienedicarboxylic (2) acids, because these were predicted by McCoy to be especially sterically favorable for intramolecular hydrogen bonding in the form of their monoanions and, indeed, we have found K_1/K_2 values for these acids in DMSO of 1 × 10^(15) and 4 × 10^(16) respectively. In contrast, the corresponding value for succinic acid is about 10^8.

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Additional Information:© 2002 John Wiley & Sons, Ltd. Received 4 December 2001; revised 1 February 2002; accepted 4 February 2002. Article first published online: 5 Mar 2002. We thank the donors of the Petroleum Research Fund, administered by the American Chemical Society, for support of this research. We are also deeply indebted to the Summer Undergraduate Research Fellowship Program (SURF) for providing a Peter A. Lindstrom Summer Undergraduate Research Fellowship, and to the E. I. Du Pont Company, Dr and Mrs Chester M. McCloskey and the Camille and Henry Dreyfus Foundation for their helpful financial assistance.
Funding AgencyGrant Number
American Chemical Society Petroleum Research FundUNSPECIFIED
Caltech Summer Undergraduate Research Fellowship (SURF)UNSPECIFIED
E. I. Du Pont CompanyUNSPECIFIED
Dr. and Mrs. Chester M. McCloskeyUNSPECIFIED
Camille and Henry Dreyfus FoundationUNSPECIFIED
Subject Keywords:dibasic acid ionization; NMR and acid strengths; hydrogen bonding of dibasic acids; acid strengths in DMSO; K_1/K_2 ratios
Issue or Number:5
Record Number:CaltechAUTHORS:20151001-101403298
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Official Citation:Choi, P. J., Petterson, K. A. and Roberts, J. D. (2002), Ionization equilibria of dicarboxylic acids in dimethyl sulfoxide as studied by NMR. J. Phys. Org. Chem., 15: 278–286. doi: 10.1002/poc.488
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:60654
Deposited By: Ruth Sustaita
Deposited On:01 Oct 2015 21:39
Last Modified:10 Nov 2021 22:37

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