Hydrolysis equilibrium of dinitrogen trioxide in dilute acid solution

Abstract

Solutions of nitrous acid in dilute (0.1 M HC1) or more concentrated (~5 M HC104) acid exhibit a contribution to the ultraviolet absorbance that is quadratic in [HN02]. In dilute acid this excess absorbance is attributed to N203 formed through equilibrium 1, 2HN02 = N203 + H20. From the measured spectrum of eN2o3Ai vs. wavelength (245-260 nm) and by comparison with eN2o3 obtained in pulse radiolysis by Grátzel et al., A, is determined as (3.03 ± 0.23) X 10™3 M™1, in agreement with the value calculated thermochemically. The coefficient of physical solubility of N203 in water is computed as 0.70 ± 0.05 M atm™1. The extinction quadratic in [HNOJ is independent of acid concentration in dilute acid but increases strongly in more concentrated acid, suggesting a possible second absorbing species of stoichiometry HN203+.

Inhibition of Nitrosation by Steric Hindrance

“…The unvarying order of magnitude 10 8 M -1 s -1 found for the true rate coefficient for the N-nitrosation step when one is working with many secondary amines under conditions in which the effective nitrosating agent is thought to be dinitrogen trioxide indicates that the attack of the N 2 O 3 upon free amines must be diffusion-controlled (Casado et al, 1983(Casado et al, , 1994. This permits us to propose the following mechanism of reaction: Comparison of the experimental (eq 2) and theoretical (eq 3) rate equations affords the values of R and and hence that of k, the attack constant of N 2 O 3 on each substrate, since (Markovits et al, 1981).…”

Mechanistic studies of nitrite reactions with metalloproteins and models relevant to mammalian physiology

“…(8)) [35]. The equilibrium constant for the latter reaction has been reported to be 3 × 10 −3 M −1 in dilute acidic aqueous solutions (0.1 M HCl at 23 • C) [36].…”

Ester Hydrolysis and Nitrosative Deamination of Novocaine in Aqueous Solutions

“…Both nitrosating agents are generated in aqueous acid solutions of nitrite according to the equibrium reactions of eq 6 with K 1 ) 3.5 × 10 -7 M -1 and K 2 ) 3 × 10 -3 M -1 at 25°C (27)(28)(29).…”