Amines nitrogen substituent

The spectroscopic properties of the /V-nitrosamines, especially the nmr and mass spectra, vary widely depending on the substituents on the amine nitrogen (44—47). The nmr spectra are affected by the E—Z isomerism around the N—N partial double bond and by the axial—equatorial geometry resulting from conformational isomerism in the heterocycles (44,45). Some general spectral characteristics for typical dialkylnitrosamines and simple heterocycHc nitrosamines are given in Table 1. 

An interesting and useful property of enamines of 2-alkylcyclohexanones is the fact that there is a substantial preference for the less substituted isomer to be formed. This tendency is especially pronounced for enamines derived from cyclic secondaiy amines such as pyrrolidine. This preference can be traced to a strain effect called A or allylic strain (see Section 3.3). In order to accommodate conjugation between the nitrogen lone pair and the carbon-carbon double bond, the nitrogen substituent must be coplanar with the double bond. This creates a steric repulsion when the enamine bears a p substituent and leads to a... 

The color hues produced in the reaction do not appear to be affected by differing substituents at the amine nitrogen however electron-attracting substituents at the a-C atom appear to reduce the detection sensitivity of the reaction [1]. The colors produced remain stable for months in the dark. In the light the zones produced by primary amines fade more rapidly than those from secondary amines [1]. 

When one of the substituents on the amine nitrogen atom is ready to trap a radical formed by treatment of iV-(a-aminoalkyl)benzotriazole with Sml2, cyclization may occur. Such a situation is depicted in Scheme 102. Thus, (4-penten-l-yl)amine derivative 652 is reduced to radical 653 that is then rapidly trapped by the alkenyl group and... 

The influence of the inductive effects of the substituents present on both the amine nitrogen and benzene ring on the Co(II)/Co(III) redox potential is quite evident. 

When protonation of a probe leads to dramatic effects on the electronic absorption and emission as described above, one can expect that cations other than protons might be capable of inducing similar effects if these ions can be made to bind to the basic atom of the probe molecule. A simple but effective method to do so exists in the formal replacement of the amino substituents ofchromophores by aza crowns. In the resulting chromoionophores the amine nitrogens possess simultaneously an electron-donor... 

The polymers can be oxidized by differential pulse polarography. Their oxidation is metal-centered and leads to Ru(III) compounds. The potential is located aroimd -1-1.26 V (SCE). It can be stated that the polymers which contain the triphenylamine structure imits in the main chain show, as expected, an additional peak caused by the amine nitrogen. Substitution at the triphenylamine by electron-donating substituents lowers these potentials to 1.05 V (25), whereas acceptor substituents cause an increase of the oxidation potential (23). 

In this review, acids and bases [8] (benzoic acids, pyridines and 1,10-phenanthrolines) will be discussed as functional groups (light bulbs). They have been incorporated into bimacrocyclic structures by bis-a- or bis-orrlio-substitu-tion of the acids or bases 2,6-disubstituted benzoic acids and pyridines, and 2,9-disubstituted 1,10-phenanthrolines were used. For the construction of the lamp shade , attention had to be paid to the components. They had to be unreactive in order not to interfere with the reactive light bulbs . Therefore, for instance amine nitrogen atoms cannot be used as bridgeheads because they may act as bases. 

The basicity of the amine nitrogen appears to be an important factor for an effective asymmetric induction. Phenyl substituents on the nitrogen atom greatly retard the reaction rate. Thus, /V-phenyl- and IV.lV-diphenylgeranylamine are inert at 40°C and 24 h reaction time. Few characteristic features are worth noting. If an allylamine is secondary, the product is the corresponding imine, a more stable valence tautomer of the enamine, which cannot be detected in the reaction mixture. The exclusive formation of an ( )-enamine regardless of the double-... 

A strong interaction of fragments Ax and A2 through a bridge amine nitrogen in position 1 is apparent from the influence of substituents on the aromatic rings Arx and Ar2 on the electron density both in substituted and in unsubstituted aryl cycles. 

Locate and name any substituents, keeping in mind that the chain is numbered away from the amine group. Substituents, which are attached to the nitrogen atom instead of the carbon of the chain, are designated by a capital N. 

Increases in the steric demands of the substituent on the amine nitrogen atom in the series R1 = Me < Et < i-Pr < f-Bu shift the equilibria 63A... 

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