Reactivity of nitrogen atom

Reactivity of nitrogen atom, of thiazole and alkyl thiazole, 386 Relaxation time, 80... 

Many reactions that produce specific numbers and/or distributions of TV-substituents, or combinations of different TV-substituents, have been devised. The protecting groups boc (t-butyl-oxycarbonyl)104 and trityl (triphenylmethyl)105 are convenient since they can be removed under mild conditions. C-Substitution can alter the relative reactivity of nitrogen atoms by steric or inductive effects to determine substitution patterns (e.g., for the bis(l,2-cyclohexdiyl) cyclam (23), which preferentially bis-substitutes at the six and 16 sites).101 The presence of imine or amide functions also determine substitution patterns and the substituted imine or amide macrocycles can be reduced to the substituted cyclic amine. 

Relative reactivity of nitrogen atoms towards fluoro-olefins [136]... 

The quatemization of the nitrogen atom of the thiazole ring (the Menschutkin s reaction) by alkyl halide or methyl tosylate can be used to measure the reactivity of this atom and thus to evaluate steric and electronic effects of ring substituents. 

In the scientific sector, the understanding of the generally higher reactivity of heteroaromatic diazo components relative to that of aromatic diazonium salts has increased. The number of heterocyclic nitrogen atoms in azolediazonium ions has a marked influence on the N-H acidity of these ions. The pvalues of a series of such ions in aqueous solution at 0 °C (Scheme 12-4) indicate that the electrophilicity of the diazonio group in these compounds increases with the number of nitrogen atoms in the ring. ... 

The stabilities and reactivities of monoaminoazoles (6 and 8) vary considerably and are related to the number of nitrogen atoms in the heterocyclic ring. Physical evidence indicates that members of this family exist as primary amines (6 and 8) rather than as imino tautomers (7 and 9). Nitrogen... 

Isodesmic reactions 2 and 3 were calculated as a measure of the relative ease of formation of the aza-epoxides, in order to obtain some insight as to the effect of nitrogen atom on metabolic activation of aza-PAHs. It was presumed that formation of the epoxides is not as relevant as carbocation formation in determining the relative reactivities of Phe, BhQ and BfQ, because almost no energy differences were observed for the isodesmic reactions involving these compounds. 

Alkyl groups adjacent to the reactive annular nitrogen atom of a five-membered ring inhibit quaternization, but the magnitude of this steric effect is considerably less than in six-membered rings.75 Thus, the rate constant for the methylation of 2-fer/-butylthiazole by Mel is only 4.2 (acetone)124 and 41 (nitrobenzene)67 times less than that for the... 

It is, perhaps, relevant to say a few words about the problem of other reactive species in active nitrogen, specifically as it pertains to the NO titration technique of nitrogen atoms and NO chemistry. 

The mode of interaction of a substituent Rz ortho to a reactive center (nitrogen atom in the given example) and adjacent to a substituent R3 depends mostly on the symmetry of R2 (Scheme 104). 

Reactivity will decrease as the number of nitrogen atoms increases. Molecules with nitrogens concentrated in one ring will tend to be more reactive than those in which the nitrogens are more evenly distributed. Thus benzo[g]quinoxaline (11.31) should be more reactive than 1,9-an-thrazoline (11.29). 

A. Reactivity of Ring Atoms 1. Electrophilic Attack on Nitrogen... 

Denitrogenation reactivities of nitrogen species in gas oils were followed in the hydrotreating reactions at 340°C under 5 MPa of Ha to quantify their respective reactivities by gas chromatography-atomic emission detection (GC-AED). 

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