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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Conformational analysis of 2,2-difluoroethylamine hydrochloride: double gauche effect

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Author(s):
Silla, Josue M. [1] ; Duarte, Claudimar J. [2] ; Cormanich, Rodrigo A. [2] ; Rittner, Roberto [2] ; Freitas, Matheus P. [1]
Total Authors: 5
Affiliation:
[1] Univ Fed Lavras, Dept Chem, BR-37200000 Lavras, MG - Brazil
[2] Univ Estadual Campinas, Inst Chem, Campinas, SP - Brazil
Total Affiliations: 2
Document type: Journal article
Source: Beilstein Journal of Organic Chemistry; v. 10, p. 877-882, APR 16 2014.
Web of Science Citations: 7
Abstract

The gauche effect in fluorinated alkylammonium salts is well known and attributed either to an intramolecular hydrogen bond or to an electrostatic attraction between the positively charged nitrogen and the vicinal electronegative fluorine atom. This work reports the effect of adding a fluorine atom in 2-fluoroethylamine hydrochloride on the conformational isomerism of the resulting 2,2-difluoroethylamine chloride (2). The analysis was carried out using NMR coupling constants in D2O solution, in order to mimic the equilibrium conditions in a physiological medium, in the gas phase and in implicit water through theoretical calculations. Despite the presence of sigma(CH)->sigma({*})(CF) and sigma(CH)->sigma({*})(CN) interactions, which usually rule the hyperconjugative gauche effect in 1,2-disubstituted ethanes, the most important forces leading to the double gauche effect (+NH3 in the gauche relationship with both fluorine atoms) in 2 are the Lewis-type ones. Particularly, electrostatic interactions are operative even in water solution, where they should be significantly attenuated, whereas hyperconjugation and hydrogen bond have secondary importance. (AU)

FAPESP's process: 12/03933-5 - Conformational equilibria and intramolecular interactions for a series of amino-acids: theoretical and experimental approaches
Grantee:Roberto Rittner Neto
Support type: Regular Research Grants
FAPESP's process: 11/11098-6 - Conformational analysis of some methyl esters of amino acids and their N-acetyl-derivatives.
Grantee:Claudimar Junker Duarte
Support type: Scholarships in Brazil - Doctorate
FAPESP's process: 11/01170-1 - Physicochemical studies of organic compounds: long range inractions and conformational analysis of organofluorine compounds.
Grantee:Rodrigo Antonio Cormanich
Support type: Scholarships in Brazil - Doctorate