The hydrogen NMR spectrum of cyclobutanone and the carbon-13 satellites have been obtained at higher resolution than hitherto. More accurate spectral parameters have been derived: it was discovered that spectral simulation by computer is a more sensitive method than computer iterative techniques.
The fluorine, the fluorine-carbon-13 satellite and the carbon-13 decoupled and undecoupled NMR spectra are reported. All the chemical shifts and coupling constants have been evaluated. Of particular interest are the 4JFF values of −1/sd1 Hz and −6·2 Hz for the cis and trans couplings respectively: few such values are known for four-membered ring compounds.
From a knowledge of the signs and magnitudes of fluorine-fluorine coupling constants of related compounds it has been possible to build up a self-consistent picture of the conformational preferences of fluorochloroacetones. Satisfactory correlation has been obtained for fluorine chemical shifts and the total of halogen electronegativities. One-bond carbon-fluorine coupling constants have been evaluated.
