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ERIC Number: EJ1067414
Record Type: Journal
Publication Date: 2015-Jun
Pages: 5
Abstractor: As Provided
Reference Count: 16
ISBN: N/A
ISSN: ISSN-0021-9584
NMR Determination of Hydrogen Bond Thermodynamics in a Simple Diamide: A Physical Chemistry Experiment
Morton, Janine G.; Joe, Candice L.; Stolla, Massiel C.; Koshland, Sophia R.; Londergan, Casey H.; Schofield, Mark H.
Journal of Chemical Education, v92 n6 p1086-1090 Jun 2015
Variable temperature NMR spectroscopy is used to determine the ?H° and ?S° of hydrogen bond formation in a simple diamide. In this two- or three-day experiment, students synthesize N,N'-dimethylmalonamide, dimethylsuccinamide, dimethylglutaramide, or dimethyladipamide from methylamine and the corresponding diester (typically in 50% recrystallized yield) and record NMR spectra at temperatures between 200 and 313 K. Solutions of N-methylacetamide in concentrations between 1.00 mM and 13.1 M (neat) are prepared and their NMR spectra recorded to determine the chemical shift of the amide proton in the hydrogen-bonded (d[subscript B]) and nonbonded (d[subscript N]) limits. By using these data, the equilibrium constants, ?H°, and ?S° for the conversion of an open-chain diamide to a cyclic structure with an intramolecular hydrogen bond are determined.
Division of Chemical Education, Inc and ACS Publications Division of the American Chemical Society. 1155 Sixteenth Street NW, Washington, DC 20036. Tel: 800-227-5558; Tel: 202-872-4600; e-mail: eic@jce.acs.org; Web site: http://pubs.acs.org/jchemeduc
Publication Type: Journal Articles; Reports - Descriptive
Education Level: Higher Education; Postsecondary Education
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A