Nitrogen components, isolation

The flavonoidal alkaloids have thus been found widely scattered throughout the higher plants. In view of the ubiquitous occurrence of flavonoids and the simplicity of the nitrogenous component in the compounds so far isolated, it is quite possible that they may occur in more species. The occurrence of the flavonoid alkaloids in Buchenavia but not Terminalia has been used to confirm the taxonomic distinction between these genera (6). 

The basic philosophy behind our approach to this problem is to develop a procedure that will allow us to isolate from humic acids and fulvic acids fractions which are rich in unidentified nitrogen but which contain only small amounts of known nitrogen compounds. We believe that the availability of such fractions will make possible the isolation and identification of some of the major unidentified nitrogen components without interference from the many known nitrogen-containing constituents. 

Zacharius, R. M. Composition of the nitrogenous components of the bush bean seed (Phaseolus vulgaris) including isolation of 5-acetylornithine. Phytochemistry 9, 2047 (1970). 

The distinction between these two classes of reactions is semantic for the five-membered rings Diels-Alder reaction at the F/B positions in (269) (four atom fragment) is equivalent to 1,3-dipolar cycloaddition in (270) across the three-atom fragment, both providing the 47t-electron component of the cycloaddition. Oxazoles and isoxazoles and their polyaza analogues show reduced aromatic character and will undergo many cycloadditions, whereas fully nitrogenous azoles such as pyrazoles and imidazoles do not, except in certain isolated cases. 

In the carbon-14 expts, HMX/RDX product was isolated qualitatively, separated Into its components, and each component assayed for carbon-14 beta radioactivity using a liquid scintillation counting technique (Ref 11). DPT-l4C was isolated as an intermediate product from the reaction mixt and similarly radioassayed. For the nitrogen-15 tagged AN expts, HMX and RDX were assayed mass spectrometrically for i5N/i4N ratios from which atom %1SN contents were calcd. In die course of these expts, each tagged species was added initially and also at subsequent stages of the reaction process. The important observations and results are summarized as ... 

Fig. 2. Components of Li enthalpies of complexation with methylamines. Successive steps indicate the effect on energy of interaction between Li and the amine of inclusion of additional components of the binding energy. The diagram shows that the permanent dipoles on amines (the charge on the nitrogen of the isolated amine) favor ammonia over trimethylamine complexation, but that polarizability and inductive effects (shift of negative charge onto the nitrogen in the complex) cause a massive turnaround in favor of complexation with trimethylamine rather than ammonia. Of particular importance is the near inversion of order caused by the addition of repulsive van der Waals terms. Modified after Ref. (9).

The chemistry of uranium interacting with atmospheric components, like carbon, nitrogen, and oxygen, poses a formidable challenge to both experimentalists and theoreticians. Few spectroscopic observations for actinide compounds are suitable for direct comparison with properties calculated for isolated molecules (ideally, gas phase data are required for such comparisons). It has been found that even data for molecules isolated in cryogenic rare gas matrixes, a medium that is usually considered to be minimally perturbing, can... 

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