Related Experiment Video
Updated: Jun 1, 2026

Synthesis of pH Dependent Pyrazole, Imidazole, and Isoindolone Dipyrrinone Fluorophores using a Claisen-Schmidt Condensation Approach
Published on: June 10, 2021
4,4'-(o-Phenyl-enedioxy-dimethyl-ene)dipyridinium dinitrate
Abstract:
The cation of the salt, C(18)H(18)N(2)O(2) (2+)·2NO(3) (-), lies about a twofold rotation axis. The pyridinium ring is almost coplanar with the phenyl-ene ring [dihedral angle between rings = 5.69 (9)°]. The crystal structure shows π-π stacking inter-actions [centroid-centroid distance = 3.70 (1) Å] between the pyridinium rings and the phenyl-ene rings, generating a linear chain structure. The cation also forms two N-H⋯O hydrogen bonds to two nitrate groups.
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1° Amines to Diazonium or Aryldiazonium Salts: Diazotization with NaNO2 Overview
The nitrous acid is unstable. Hence, it is formed in situ from a solution of sodium nitrite and cold aqueous acids such as hydrochloric or sulfuric acid. In an acidic solution, the –OH group of nitrous acid undergoes protonation to give oxonium ion, followed by water loss...

