29233-93-0Relevant academic research and scientific papers
Identification and quantification of aerosol polar oxygenated compounds bearing carboxylic or hydroxyl groups. 1. Method development
Jaoui,Kleindienst,Lewandowski,Edney
, p. 4765 - 4778 (2007/10/03)
In this study, a new analytical technique was developed for the identification and quantification of multifunctional compounds containing simultaneously at least one hydroxyl or one carboxylic group, or both. This technique is based on derivatizing first the carboxylic group(s) of the multifunctional compound using an alcohol (e.g., methanol, 1-butanol) in the presence of a relatively strong Lewis acid (BF3) as a catalyst. This esterification reaction quicldy and quantitatively converts carboxylic acids to their ester forms. The second step is based on silylation of the ester compounds using bis(trimethylsilyl) trifluoroacetamide (BSTFA) as the derivatizing agent. For compounds bearing ketone groups in addition to carboxylic and hydroxyl groups, a third step was used based on PFBHA derivatization of the carbonyls. Different parameters including temperature, reaction time, and effect due to artifacts were optimized. A GC/MS in EI and in methane-CI mode was used for the analysis of these compounds. The new approach was tested on a number of multifunctional compounds. The interpretation of their EI (70 eV) and CI mass spectra shows that critical information is gained leading to unambiguous identification of unknown compounds. For example, when derivatized only with BF3-methanol, their mass spectra comprise primary ions at m/z M .+ + 1, M.+ + 29, and M.- - 31 for compounds bearing only carboxylic groups and M.- + 1, M.+ + 29, M.+ - 31, and M+. - 17 for those bearing hydroxyl and carboxylic groups. However, when a second derivatization (BSTFA) was used, compounds bearing hydroxyl and carboxylic groups simultaneously show, in addition to the ions observed before, ions at m/z M.+ + 73, M .+ - 15, M.+ - 59, M.+ - 75, M.+ - 89, and 73. To the best of our knowledge, this technique describes systematically for the first time a method for identifying multifunctional oxygenated compounds containing simultaneously one or more hydroxyl and carboxylic acid groups.
Synthesis of optically active α-hydroxycarbonyl compounds by (salen)Mn(III)-catalyzed oxidation of silyl enol ethers and silyl ketene acetals
Adam, Waldemar,Fell, Rainer T.,Mock-Knoblauch, Cordula,Saha-Moeller, Chantu R.
, p. 6531 - 6534 (2007/10/03)
Optically active α-hydroxy ketones and esters have been prepared by (salen)Mn(III)-catalyzed asymmetric oxidation of silyl enol ethers and silyl ketene acetals in high enantioselectivity, with ee values up to 81% for the α-hydroxy ketones and up to 57% for α-hydroxy esters. The extent of conversion and the enantioselectivity depends strongly on the type of oxygen donor, the pH of the aqueous bleach medium, the additive, and the substitution pattern at the enol functionality.
Synthesis of Enantiomerically Pure α-Hydroxyaldehydes from the Corresponding α-Hydroxycarboxylic acids: Novel Substrates for Escherichia coli Transketolase
Humphrey, Andrew J.,Turner, Nicholas J.,McCague, Raymond,Taylor, Stephen J. C.
, p. 2475 - 2476 (2007/10/03)
Enantiomerically pure (R)-α-hydroxyaldehydes (>95percent ee) are prepared from the corresponding α-hydroxyesters by silyl protection, reduction with diisobutylaluminium hydride, and finally deprotection under acidic conditions; subsequent coupling of these aldehydes with lithium hydroxypyruvate, catalysed by Escherichia coli transketolase, leads to novel optically pure triols.
Synthesis of Aryl Carbohydrate Synthons and 2,3-Dihydroxypropanoic Acid Derivatives of High Optical Purity
Matthews, Barry R.,Jackson, W. Roy,Jacobs, Howard A.,Watson, Keith G.
, p. 1195 - 1214 (2007/10/02)
General routes to bith L and D aryl carbohydrate precursors and to erythro and threo 2,3-dihydroxypropanoic acid of high optical purity have been established from readily available optically active aryl cyanohydrins.
