Rotational isomerism—XII Rotamer energies and 3JHF and 4JHH couplings in 1-chloro-2-bromo-2-fluoropropane (1)

✍ Scribed by R. J. Abraham; W. L. Oliver Jr.

• Publisher: John Wiley and Sons
• Year: 1971
• Tongue: English
• Weight: 413 KB
• Volume: 3
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/mrc.1270030612

✦ Synopsis

The complete analysis of the NMR spectrum of CH,CI.CFBr.CH, in CCI, and acetone is given. The long range 'JHH couplings in this molecule differ considerably and surprisingly are both positive. An analysis of the solvent dependence of the couplings enables the rotamer couplings and energies to be obtained. The rotamer energies and their variation with solvent are in accord with quantitative predictions and results from similar halogenated ethanes. The values of the couplings can be rationalised in terms of substituent electronegativity effects.

* Recent work in our laboratory shows that taking all CX dipole moments of 1.8 D gives better agreement with experiment than 5ur previous values (CH2X 2.03, CHX, 1.79 D).