Modeling of 4-Carboxyl-2,6-dinitrobenzenediazonium Ion (CDNBD) Hydrolysis Through Addition of Water and Alkaline Buffer in a Strongly Acidic Medium

Abstract

The transition from aryl diazonium reagent solution to a crystalline form has substantial merits, namely augmented stability and versatility. Absorbance decay data was from photometric titration with hydroxyl ion, supplied incrementally by water and alkaline buffer (pH 12.0), to 4-carboxyl-2,6-dinitrobenzenediazonium ion (CDNBD) and simpler analogs in a strongly acidic medium. The data were fitted to nested models (mono- and bi-exponential decay). Akaike’s Information Criterion was used for statistical model comparison. Preferred model identification shows simpler diazonium analogs are less reactive towards hydroxyl ion when alkaline buffer solution is the diluting medium. In contrast, CDNBD hydrolysis is faster when an alkaline diluting medium is added, owing to profound positive effect of strong electron withdrawing groups on its electrophilic reactivity. Acidic diluting medium was shown, unambiguously, as a critical requirement for maintaining CDNBD, in an acidic solution as the cation species. Key input process variables were reliably predicted, using model parameters like $V_{1/2}$ and $V_{1/2}^{T}$, thus giving direction for optimal synthesis of crystalline CDNBD.