Nitrogen mass spectral interpretation

A very simple and useful rule to aid in the interpretation of the MS data of organic compounds relates to the fact that nitrogen has an even mass but an odd valency, whereas the valency and mass for the most abundant isotope of other elements are either both odd or both even. This gives us a very simple rule that we can immediately apply to any mass spectral data the nitrogen rule which is given in Box 5.2. 

Mass spectral data have frequently been used in the structural determination of boron heterocycles. One paper has been devoted to the mass spectra of some six-membered boron-nitrogen systems. It was concluded that the spectra could be interpreted analogously to their hydrocarbon counterparts. In all cases the molecular peak was the base peak of the spectrum (68T6755). Doubly charged molecular ions, a feature typical of aromatic compounds, are often encountered. It should be noted, however, that some certainly non-aromatic aminoboranes give such doubly charged ions as well. 

Interpretation of these mass-spectral data in Table IV combined with the titration data from Table III allows additional inference concerning the characteristics of the nitrogen compounds present in the very weak base concentrate. The sum of the compound types listed as pyrroles and indoles (Z =-= —7, —9, —11, and —13) amounts to 29% of the total. These compound types have given (II) very weak base titers of about 70% of theoretical thus it appears likely that the 19.8% titer for very weak bases in Table III may come from the titration of the pyrroles and indoles in this concentrate. In addition, they are not N-substituted... 

A mass spectral examination of luciduline and several of its derivatives was undertaken. The spectra were all interpretable on the basis of structure 69, thus lending credence to its validity. An X-ray study of the j9-bromobenzoate of 70 fully confirmed the conclusions drawn from the chemical and spectroscopic studies and at the same time established the relative configuration at C-8 and the absolute configuration of the molecule. The X-ray study showed that the molecule is somewhat distorted from an ideal chair toward a half-chair conformation in rings A and C. In this way the interaction between the axial hydrogen at C-1 and the nitrogen is considered to be relieved. 

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