NITROGEN-CONTAINING MOLECULES

The rates of loss of a propyl radical from n-butylamine following FI have been measured using a single-focussing mass spectrometer [825]. 

Rates of decomposition of the molecular ions of aminotriazoline stereoisomers have been determined over the time range tens of picoseconds to microseconds using a blade emitter and a double-focussing mass spectrometer [399]. The predominant process at the shortest times was, in all cases, loss of molecular nitrogen. The stereoisomers decomposed at very different rates, which was interpreted in terms of differing rate coefficients, k(E), arising from different amounts of steric strain. 

Decomposition of negative m-nitrobenzoic acid ions to lose OH- has been observed at short times [856]. 

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Outline the laboratory preparation of a sample of dinitrogen tetroxide. Describe and explain what happens when it is heated from 290 K to 900 K. Suggest electronic structures for dinitrogen tetroxide and the other nitrogen-containing molecules formed from it on heating to 900 K. Point out any unusual structural features. 

A large number and diverse classes of compounds have been reported to possess tyrosinase inhibitory activities to various extents from the millimo-lar to nanomolar concentration ranges. From our laboratory we have also reported a large variety of tyrosinase inhibitors and for some of them we have performed molecular modeling as well. Among them there are several alkaloids, and nitrogen-containing molecules are also present. 

In conclusion, the BAL method is a novel and general strategy for solid-phase synthesis of peptides and peptide derivatives, is compatible with a wide range of functionalized polymeric supports, and is readily generalizable to other nitrogen-containing molecules.9... 

In this section we provide a short comparison of conformational energies for a set of nitrogen-containing molecules as obtained by several commonly used molecular mechanics force fields and by experiment. The data, collected in Table 22, were mostly taken from Reference 60 but several were calculated for this work. 

APPLICATION OF MOLECULAR MECHANICS CALCULATIONS 3. Nitrogen-Containing Molecules... 

Despite considerable development in the experimental conformational analysis of nitrogen-containing molecules (189), MM applications to this class of molecules are rare, primarily because of the lack of good parameters (Table 8). Now that MM2 (and to a lesser extent MMI) includes well-tested (170 parameters for nitrogen in sp, sp, and sp configurations, more applications will be seen in the near future. 

While anodic amide oxidations have found the most synthetic use to date, the oxidation of nitrogen-containing molecules is not limited to amide substrates. A variety of amine oxidations have been studied, and the Kolbe electrolysis of carboxylic acids has been used to generate nitrogen-based reactive intermediates. Many of these reactions also offer unique synthetic advantages (Sects. 10.2 and 10.3). 

Table 8.4 Some small nitrogen-containing molecules synthesised from amino acids...

Reduced crystallite size of the zeolite and/or breaking or grinding of clusters of zeolite crystals to individual crystals, also serves to enhance accessibility in the face of asphaltenes, nitrogen-containing molecules, destructive and harmful elements, and other molecular "clutter" associated with the bottom of the barrel. 

Imines and (Af,(9)-acetals from fluoral are useful precursors of trifluoromethyl nitrogen-containing molecules amines, amino alcohols, amino acids, peptidomimetic units, heterocycles, and so on (Figure 2.50). These simple Af-derivatives of fluoral are easily prepared from the hydrate or the hemiacetal. Imines of fluoral react in [2 + 1 ]... 

What s DNA Deoxyribonucleic acid, the helical ladderlike chain of molecules that makes up genes. DNA consists of a sugar molecule called deoxyribose (it is somewhat related to glucose), a nitrogen-containing molecule called a base, and phosphate atoms bonded to the other two components. It is the sequence of base pairs (one base on each strand) in DNA that determines the end-product (e.g., protein). The human genome— the entire DNA content of a human being—contains approximately 3 billion base pairs. 

Nitrogenous base. An aromatic nitrogen-containing molecule with basic properties. Such bases include purines and pyrimidines. 

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