Β-hydroxy Carboxylic Acids Research Articles

Gas chromatography and mass spectrometry of the trimethylsilyl ether methyl ester derivatives of long chain hydroxy acids from Nocardia corallina

The hydroxy acids from Nocardia corallina were fractionated on the basis of molecular weight by gas chromatography of their trimethylsilyl ether methyl esters. Mass spectrometric analysis of the trimethylsilyl derivatives suggested the occurrence of three types of parent acid which varied in carbon number from C 38 to C 48, in the degree of unsaturation and in the position of the β-hydroxycarboxylic acid moiety in the carbon chain.

Study of some mono-, di- and tricarboxylic acids in aqueous solution by the nuclear magnetic resonance technique

The nuclear magnetic resonance spectra of aqueous solutions of three β-hydroxy carboxylic acids and some of their derivatives were measured as a function of the pH. The chemical shifts of the methylene hydrogens, adjacent to the carboxyl group, exhibit titration curves. The chemical shift between the two methylene hydrogens behaves differently in each compound, the most common behaviour being the occurrence of a minimum in the shift at pH ⋍ pK. The value of the spin—spin coupling constant changes only very slightly with the pH. The effect of added neutral salts and the variation of the temperature were also investigated in some of the acids. Qualitative conclusions concerning inter- and intramolecular hydrogen bonds and electrostatic interactions in these molecules were derived from the results.