Polar aspects of intramolecular interactions in 2‐amino‐5‐nitro‐4‐methylpyridines and 2‐amino‐3‐nitro‐4‐methylpyridines

The dipole moments of twelve 2‐ N ‐substituted amino‐5‐nitro‐4‐methylpyridines ( I‐XII ) and three 2‐ N ‐substituted amino‐3‐nitro‐4‐methylpyridines ( XIII‐XV ) were determined in benzene. The polar aspects of intramolecular charge‐transfer and intramolecular hydrogen bonding were discussed. The interaction dipole moments, μ int , were calculated for 2‐ N ‐alkyl(or aryl)amino‐5‐nitro‐4‐methylpyridines. Increased alkylation of amino nitrogen brought about an intensified push‐pull interaction between the amino and nitro groups. The solvent effects on the dipole moments of 2‐ N ‐methylamino‐5‐nitro‐4‐methyl‐( I ), 2‐ N,N ‐dimethylamino‐5‐nitro‐4‐methyl‐ ( II ) and 2‐ N ‐methylamino‐3‐nitro‐4‐methylpyridines ( XIII ) were different. Specific hydrogen bond solute‐solvent interactions increased the charge‐transfer effect in I , but it did not disrupt the intramolecular hydrogen bond in XIII.