Basicity of azoles

Orientation in azole rings containing three or four heteroatoms Effect of azole ring structure and of substituents Proton acids on neutral azoles basicity of azoles Proton acids on azole anions acidity of azoles Metal ions... 

Proton acids on neutral azoles, basicity of azoles... 

Proton Affinities and Intrinsic Basicities of Azole Anions ... 

A different analysis has been carried out for the basicity of azoles (86JA3237). It leads to the conclusion that the position of the following equilibrium ... 

N-Methylation of azoles has no direct counterpart in the case of pyridines. As indicated in Section IV,A, experimental evidence shows that N-methylation increases the intrinsic basicity of azoles at least as much as C-methylation. This pattern is not reproduced in aqueous solution, where N-methylation either reduces or has no effect and the derived ions are solvated to a lesser extent than those of the parent compounds. 

Phenyl groups are weak resonance donors, but inductive acceptors. Phenyl groups are therefore expected to reduce the basicity of azoles. 

Solvent effects are found to operate in a similar way with regard to the basicity of azoles, benzazoles, and benzazoles carrying a methyl group a to the basic center (84JHC269). Again, three families of compounds, whose pK, values correlate with the ionization energy of the nitrogen lone pair (the basic... 

The pathways of transformation of /V-ha oazoles in water and in acidic and basic media to a large extent depend on the basicity of azoles, the ease of heterolysis of the A-halogen bond, and the capability of further ring transformations. 

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