Kinetic analysis and subambient temperature on-line on-column derivatization of an active aldehyde

The chromatographic analysis of aldehydes under typical reversed-phase conditions may be a challenging task due to an equilibrium process leading to the formation of a gem diol species regardless of acidic or basic conditions. Initially, a reversed-phase HPLC gradient elution was developed to determ...

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Bibliographic Details
Published in:Journal of Chromatography A 2003-05, Vol.995 (1), p.67-78
Main Authors: LoBrutto, R, Bereznitski, Y, Novak, T.J, DiMichele, L, Pan, L, Journet, M, Kowal, J, Grinberg, N
Format: Article
Language:English
Subjects:
Aldehydes
Aldehydes - chemistry
Analytical chemistry
Chemistry
Chromatographic methods and physical methods associated with chromatography
Chromatography, High Pressure Liquid - methods
Exact sciences and technology
Kinetics
Magnetic Resonance Spectroscopy
Other chromatographic methods
Temperature
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Summary:The chromatographic analysis of aldehydes under typical reversed-phase conditions may be a challenging task due to an equilibrium process leading to the formation of a gem diol species regardless of acidic or basic conditions. Initially, a reversed-phase HPLC gradient elution was developed to determine the amount of an acetylenic aldehyde in a reaction mixture. Significant fronting was observed under acidic and basic conditions even at −5 °C. In order to circumvent this problem, a reversed-phase HPLC gradient method on a C 18 column at subambient temperature was developed using diethylamine as a mobile phase additive for on-line on-column derivatization of the aldehyde moiety. The on-line on-column reaction rate for the derivatization of the aldehyde with diethylamine was determined as a function of column temperature. An Arrhenius plot was constructed and the activation energy was calculated. The chromatographic behavior of the derivatized acetylenic aldehyde and products formed in-situ in the chromatographic system were studied at various temperatures ranging from −10 to 60 °C. It was found that the reaction products could be controlled by adjusting the column temperature. Different reaction pathways were identified as a function of temperature. The products and the reaction pathways were characterized by NMR, LC–MS and UV spectra.
ISSN:0021-9673
DOI:10.1016/S0021-9673(03)00532-6