Showing papers by "Asher Mandelbaum published in 1994"
TL;DR: The application of pH-zone-refining counter-current chromatography (CCC) to the preparative separation of stereoisomeric acids is described and the separation was accomplished on the basis of the difference in acidity of the two stereoisomers.
24 citations
TL;DR: In this paper, a mass spectral study of the isomeric mixed methyl ethyl esters of the diacid, substituted by a methyl group at position 1 and deuterium labelled at position 3, indicates a stepwise mechanism for this alcohol elimination.
Abstract: Diesters of cyclohexane trans-1,3-dicarboxylic acid give rise to major [M − ROH] +. ions under electron impact ionization. A mass spectral study of the isomeric mixed methyl ethyl esters of the diacid, substituted by a methyl group at position 1 and deuterium labelled at position 3, indicates a stepwise mechanism for this alcohol elimination; the 3-hydrogen (or deuterium) is transferred to the carbonyl of the 1-ester group in the initial step. Subsequent migration of that hydrogen (or deuterium) to the alkoxyl of position 3 results in the highly site- and stereospecific alcohol elimination. CID spectra of the [M − ROH] +. ions obtained from the stereoisomeric diesters clearly show that they have different structures (or are different mixtures of structures)
2 citations