NO.3 A-60 AT WORK SERIES
An examination of the Ν MR spectrum revealed a single proton whose resonance at δ = 5.0 was in the position expected for the tertiary proton in Structure I. The band at s = 6.8 to 8.3 was assigned to the nine phenyl protons plus the proton on the conjugated double bond, and the two peaks at δ = 2.5 and 6 = 1.4 were assigned to the a protons and the remaining protons in the heterocyclic ring. The integrated intensities shown on the chart support these assignments. Thus the NMR spectrum served to eliminate Structure II.
NMR
IN T H E W O R L D OF CHEMISTRY
Thé discrepancy between chemical, UV, IR, and NMR data thus led to a reconsideration of the structure possibilities of the compound. The result was the proposal of Structure III (shown on the chart at right) which is simply an allylic rearrangement of Structure I. Chemical properties of the compound and the UV, IR, and NMR spectral data are all consistent with this structure. This example demonstrates the complimentary nature of NMR and the other branches of spectroscopy in the solution of a rather subtle structural problem.
We are grateful to Regents* Professor Norman H. Cromwell of the University of Nebraska for permission to4i$çH$S ttiesetresutts^
In addition to determining molecular structures, the Varian A-60 offers a rapid, non-destructive means of identifying compounds, functional groups, isotopic substitution sites, and components of mixtures. It is extremely useful in the study of hydrogen bonding, chemical kinetics, tautomeric equilibria, and the determination of total hydrogen content. Because it provides reproducible spectra on pre-calibrated charts, the easy-to-operate A-60 has made the valuable analytical capabilities of NMR practical for many routine applications in universities, government and industrial plants and laboratories. For additional information, please write the INSTRUMENT DIVISION.
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