Nitrogen general aspects

Introduction.—Few reviews have appeared dealing with more or less general aspects of cyclophosphazene chemistry. The role of cyclophosphazenes as model compounds for reactions of their polymeric analogues has been discussed some fundamental subjects in the area of phosphorus-nitrogen chemistry such as aminolysis, alcoholysis, hydrolysis, and tautomerization phenomena have also been discussed. An extensive review has appeared dealing with reactions of phosphazenes with alkoxides and aryloxides. ... 

Six articles cover general aspects of heterocyclic chemistry 1,3-dipolar cycloreversions, syntheses with arylnitrenes and a-metallated isocyanides, and photo-oxygenation of nitrogen heterocycles,while others deal with more specialized subjects, i.e. preparation and use of halogeno-lactones, aspects of the chemistry of furan, 1-hydroxy-indoles, ring-opening of azoles by the action of amines, " the use of 2-chlorobenzoxazolium (1) and other heterocyclic onium salts for dehydration and condensation reactions," the synthesis of monosub-stituted tetrathiafulvalenes (2), cycloadditions of azoles containing three heteroatoms,sydnone imines (3), the conversion of acyl-benzofuroxans into nitro-indazoles (cf. p. 199), and advances in the chemistry of pyrrolizidine " and indolizine." ... 

The first generalization is illustrated by the behavior of the 2- and 4-vs. the 3-derivatives of pyridine, the second by the reactivity of 4- vs. 2-substituted pyridines, the third by the relation of 4- vs. 2-derivatives of pyrimidine, and the fourth by the appreciable reactivity of 3-substituted pyridines or 5-substituted pyrimidines compared to that of their benzene analogs. Various combinations of azine-nitrogens in other poly-azines supply further examples. Theoretical aspects of (1), (2) and (3) are discussed in Section II, B, 2. The effect involved in (4) is believed to be more the result of the inductive stabilization of an adjacent negative chaise in the transition state (cf. 251) than of the electron deficiency created in the ground state (cf. 252). The quantitative relation between inductive stabihzation and resonance stabilization is not precisely defined by available data. However, a... 

Research on plasma-deposited a-C(N) H films has been frequently included in the general discussion of carbon nitride solids [2, 3]. However, the presence of hydrogen in its composition, and the complexity of the deposition process, which introduces the nitrogen species in the already intricate hydrocarbon plasma-deposition mechanism, make a-C(N) H films deserve special consideration. This is the aim of the present work to review and to discuss the main results on the growth, structure, and properties of plasma-deposited a-C(N) H films. As this subject is closely related to a-C H films, a summary of the main aspects relative to the plasma deposition of a-C H films, their structure, and the relationship between the main process parameters governing film structure and properties is presented... 

Jess, A., Popp, R., Hedden, K. 1999. Fischer-Tropsch-synthesis with nitrogen-rich syngas—Fundamentals and reactor design aspects. Applied Catalysis A General 186 321-42. 

Nitrogen. Pyridine is one of the most important heterocycles. The aromaticity of pyridine was intensively connected to structural considerations and chemical behavior. The relative difference between the aromaticity of benzene and pyridine is controversial generally calculations give similar orders of magnitude and differences depend on the criterion of aromaticity considered and the mode of calculation used. A comprehensive review on the theoretical aspects in connection with the aromaticity of pyridine was published.191 Pyridine is about as aromatic as benzene according to theoretical calculations and to experimental data, while quinoline is about as aromatic as naphthalene and more aromatic than isoquinoline.192193 The degrees of aromaticity of pyridine derivatives strongly depend on their substituents. 

Most of the important general methods of forming IZf-triazole derivatives involve azides several reviews discuss aspects of the formation of triazoles in this way. a-Diketones are also important precursors of both H- and 2 f-triazoles. Triazoles unsubstituted on nitrogen can be prepared by the direct addition of hydrazoic acid or of azide ion, but it is often more convenient to obtain these compounds by removal of a substituent from a H- or 2if-substituted triazole (Section IV, E). 

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