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17 O NMR spectroscopy: Intramolecular hydrogen bonding in hydroxypyridine carboxy esters

1992; Wiley; Volume: 29; Issue: 1 Linguagem: Inglês

10.1002/jhet.5570290101

1943-5193

David W. Boykin, Arvind Kumar,

Structural and Chemical Analysis of Organic and Inorganic Compounds

Abstract Natural abundance 17 O nmr chemical shift data for 8 aryl esters and 10 pyridine carboxy esters, including 6 ortho ‐hydroxy esters, recorded in acetomitrile at 75° are reported. The carbonyl group 17 O nmr chemical shift data for methyl 2‐, 3‐ and 4‐pyridinecarboxylate are correlated with σ + constants. The hydrogen bonding component (Δδ HB ) to the ester carbonyl 17 O nmr chemical shift for the intramolecular hydrogen bonded ortho ‐hydroxy systems are 9.8 ppm, 13.6 ppm and 4.3 ppm for benzoates, 2‐pyridinecarboxylates and 4‐pyridinecarboxylates, respectively. The relationships of the ester Δδ HB values to other hydrogen bond acceptor Δδ HB values are discussed.