nuclear magnetic resonance (NMR)
Springer Online Journal Archives 1860-2000
Chemistry and Pharmacology
Abstract IR and 1H NMR studies in CDCl3 and CCl4 of a series of tertiary aminoxylidides with the amino group in the 2 to 6 position of the acyl chain are described. Lidocaine, diethylaminoaceto-2′,6′-xylidide, forms an intramolecular five-membered ring hydrogen-bonded monomer at all concentrations in both solvents. β-Diethyl-amino-propiono-2′,6′-xylidide forms an intramolecular six-membered ring hydrogen-bonded monomer in CDCl3 and CCl4 but a trans intermolecularly associated species is the major form present at high concentrations in CCl4. The longer-chain homologues are mixtures of nonassociated trans and cis monomers at low concentrations but associated trans forms predominate at high concentrations. Evidence for the presence of a hydrogen-bonded seven-membered ring intramolecular monomer in CDCl3 for γ-diethylaminobutyro-2′,6′-xylidide is presented. The relationship between the molecular conformation and the partition coefficient is discussed.
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