ISSN:
0030-4921
Schlagwort(e):
Chemistry
;
Analytical Chemistry and Spectroscopy
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
Data for 30 hydrogen bonding pairs taken from the alkanethiols, i-C3H7SH, nC3H9SH and t-C4H9SH, and 16 bases have been obtained by a PMR method. Representative data for i-C3H7SH at 304 ± 2°K are (base, 102K in M-1, -ΔH° in kcal/mole): (CH2)4S, 3·1, 0·8; (CH3)2S, 3·0, 0·9; (CH3)2S2, 3·7, 0·5; (CH3)2CO, 4·7, 0·9; CH3COOC2H5, 5·7, 1·1; (CH2)4O, 6·1, 1·0; HCON(CH3)2, 12, 0·9; (CH3 O)2 SO, 12, 0·9; (C2 H5O)3PO, 6·5, 1·0; CH3 (CH3 O)2PO, 18, 1·0; ((CH3)2N)2 CO, 5·9, 1·1; CH3 CN, 13, 0·6. In essence, the problems and errors involved in obtaining equilibrium data for weak complexes stem from the limited concentration rangethat is accessible. This leads to large uncertainties in the quantities K, ΔH° and ΔS°. Structural effects on hydrogen bonding at the sulfur site, both as Lewis acid or base, are discussed. Two erroneous PMR methods in the literature used for assessing the strength of hydrogen bonds are pointed out.
Zusätzliches Material:
2 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/mrc.1270040508
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