Open AccessSelective Nuclear Magnetic Resonance Experiments for Sign-Sensitive Determination of Heteronuclear Couplings: Expanding the Analysis of Crude Reaction Mixtures
Author(s) -
Guilherme Dal Poggetto,
João Vitor Soares,
Cláudio F. Tormena
Publication year - 2020
Publication title -
analytical chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.117
H-Index - 332
eISSN - 1520-6882
pISSN - 0003-2700
DOI - 10.1021/acs.analchem.0c02976
Subject(s) - heteronuclear molecule , chemistry , sign (mathematics) , proton , analytical chemistry (journal) , resonance (particle physics) , resolution (logic) , nuclear magnetic resonance , fluorine , nuclear magnetic resonance spectroscopy , atomic physics , chromatography , nuclear physics , stereochemistry , organic chemistry , mathematical analysis , physics , mathematics , artificial intelligence , computer science
State-of-the-art nuclear magnetic resonance (NMR) selective experiments are capable of directly analyzing crude reaction mixtures. A new experiment named HD-HAPPY-FESTA yields ultrahigh-resolution total correlation subspectra, which are suitable for sign-sensitive determination of heteronuclear couplings, as demonstrated here by measuring the sign and magnitude for proton-fluorine couplings ( J HF ) from major and minor isomer products of a two-step reaction without any purification. Proton-fluorine couplings ranging from 51.5 to -2.6 Hz could be measured using HD-HAPPY-FESTA, with the smallest measured magnitude of 0.8 Hz. Experimental J HF values were used to identify the two fluoroketone intermediates and the four fluoroalcohol products. Results were rationalized and compared with the density functional theory (DFT) calculations. Experimental data were further compared with the couplings reported in the literature, where pure samples were analyzed.