53586-61-1Relevant academic research and scientific papers
Conformation in 2,3-Difluorobutanes
Angelini, G.,Gavuzzo, E.,Segre, A. L.,Speranza, M.
, p. 8762 - 8766 (2007/10/02)
A conformational analysis for meso- and d,l-2,3-difluorobutanes has been carried out, employing 1H and 19F NMR and theoretical calculations.The real configurations of the two isomers were assigned by specific optical rotation measurements of the products coming from an optically active precursor.Gauche conformations were predominant for meso (E) isomer, while the d,l (T) isomer showed all possible staggered rotamers almost equally populated.Finally remarks for NMR peak assignment of homo- and copolymers partially fluorinated by using gauche additive effects are given.
Stereochemical Consequences of Halogen Atom Substitution. 1. Rotational Conformer Effects in Gaseous Diastereomeric 2,3-Dihalobutanes
Sharma, Ram B.,Ferrieri, Richard A.,Meyer, Richard J.,Rack, Edward P.,Wolf, Alfred P.
, p. 2316 - 2320 (2007/10/02)
The stereochemical consequences of translationally excited 38Cl-for-X (X = F, Cl) substitution in (2S,3R)-meso- and (2S,3S)-dl-difluorobutane, (2S,3R)-dl- and (2S,3R)-dl-chlorofluorobutane, and (2S,3R)-meso- and (2S,3S)-dl-dichlorobutane were studied in the gas phase.Although retention of configuration was determined to be the dominant substitution pathway, substantial inversion product yields were observed in all cases.A comparison of these yields revealed that the (S,R) configuration within each set always gave a smaller yield of the inverted product than the (S,S) configuration.This observation was consistent with the hypothesis that back-side substitution was a direct mechanism and that steric hindrance to such attack was subject to differences in the rotational conformer populations within each substrate configuration.In contrast, the measured yields of retention products were insensitive to substrate configuration.
