Azides, structure

The azide (structure not stated) is not impact-sensitive, but decomposes explosively at 120°C. Blending with 75% of polymer as diluent eliminated the explosive decomposition. 

The structure is in part inferred from the observation that in boiling tetrahydrofuran the substance loses nitrogen and sulfur and gives pentyl cyanide. The absence of absorption in the neighbourhood of 2150 cm-1 indicative of an azide group excludes the thioacyl azide structure.17... 

An acyclic azide structure was rejected since the compounds show no azide IR absorption. A less likely three-membered ring was also considered. Comparison with other potential dihydro-SIV-thiatriazoles was made. Simple a-azido thioethers show the spectroscopic and chemical properties of azides rather than of dihydro-Slv-thiatriazoles. o-(Methylthio)phenyl azide was prepared but also showed the characteristics of an azide.70 These results cast doubt on the suggested structure, since the only essential difference in composition is an amino group that is not in a position to stabilize the suggested heterocyclic ring. Structure R1(R3R4N)C=N—N=N—SR2 is an alternative, but. further consideration must await X-ray crystallographic analysis. 

The heteroaromatic selenatriazole ring system (6) represents a new class of compounds isolated so far only as 5-amino-l,2,3,4-selenatriazoles. IR and mass spectra are in agreement with the selenatriazole structure and an alternative open-chain selenoacyl azide structure (7 X = Se) can be rejected because of the lack of an azide absorption in the IR heterocumulene region (ca. 2000-2300 cm-1) (82UP42800). 

A novel, nonswelling DUV resist was developed by Iwayanagi et al. (77). This resist, known as MRS (micro resist for shorter wavelengths), consists of poly(p-vinylphenol) (structure 3.11), an alkaline-soluble phenolic resin, and an azide (structure 3.10). 

The related phenomenon of Raman spectroscopy has been applied to azide chemistry, mainly in the early discussion of whether the azide structure was linear or cyclic °. 

When the azomethine group is part of an electron-deficient ring, such as pyridine, pyrimidine or thiazole, the compounds exist as tetrazoles in the solid state, and at equilibrium with the azido form in solution . The equilibrium constants depend on the solvent, the nature of the substituents and the temperature . 2-Azido-4,6-dimethylpyrimidine (288a) thus exists in equilibrium with tetrazolo-pyrimidine (288b). Its chemical behaviour is, however, in accord with the azide structure 288a, including dipolar addition reactions and nitrene reactions . 

Benati, L., Calestani, G., Nanni, D., Spagnolo, P. Reactions of Benzocyclic 3-Keto Esters with Tosyl and 4-Nitrophenyl Azide. Structural Influence of Dicarbonyl Substrate and Azide Reagent on Distribution of Diazo, Azide and Ring-Contraction Products. J. Org. Chem. 1998, 63, 4679-4684. 

Figure 10. Projection onto the (001) plane of the thallous azide structure. The azide ions are at 0,1/2,1, and lie in the plane.

GA4-17-S-propyl-S-phenacyl azide (structure I, Fig. 3) induces a-amylase in aleurone protoplasts (Fig. 1), although it is less active than the parent compound (GA4). In aqueous solution it has a X ax of294 nm (Fig. 2). Solutions are stable in the dark but are photolyzed within seconds of exposure to intense light of wavelengths above 300 nm (Fig. 2). Aryl azides photolyse to highly reactive aryl nitrenes that can covalently attach to amino acids at the binding site. See [15] for a detailed. account of the reactions of aryl nitrenes. 

Fig. 1. Dose response curves of GA and GA -IT-S-propyl-S-phenacyl azide (structure I, Fig. 3) in aleurone protoplasts...

For convenience of synthesis the preparation of a tritiated photoactive GA-derivative involved slight modification of the C-17 side chain. The GA4-photoaffinity probe, GA4-17-S-propyl-S-benzoyl azide (structure III, Fig. 3) was thus tritiated to 1.79 TBq/mmol. 

Fig. 7 Relationship between nature of the azide, structure of cyclooctyne and reaction rate constants. Reaction rate constants were determined in CD3CN D20 = 3 1...

These compounds exhibit no infrared absorption in the 2100-2200 cm range,and this definitely rules out the thiocarbamoyl azide structure. For the disubstituted derivatives of 5-amino-1,2,3,4-thiatriazole, therefore, only one structure is possible, i.e. structure 7. For the unsubstituted and monosubstituted compounds, however, it has been proposed that they exist as the tautomeric 5-imino-l,2,3,4-thiatriazolines (8). For 5-methylamino-l,2,3,4-thiatriazole this possibility is ruled out by an investigation of its n.m.r. spectrum,and this result is probably generally valid for the 5-alkylamino-l,2,3,4-thiatriazoles. The unsubstituted compound has infrared absorption bands at 3135, 3257, and 1621 cm , which may be assigned to two NH2 stretching bands and a NHg deformation band, respectively therefore it almost certainly exists as 5-amino-l,2,3,4-thiatriazole and not as 5-imino-l,2,3,4-thiatriazoline. 

HCAII/Azide Structure and Dynamics Studied by QM/MM Methods... 

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