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Solvent effects in the decomposition reaction of some products formed by the reaction of sorbic acid with sodium nitrite: 1,4‐dinitro‐2‐methylpyrrole and ethylnitrolic acid
Author(s) -
PérezPrior M. Teresa,
Manso José A.,
GómezBombarelli Rafael,
GonzálezPérez Marina,
Céspedes Isaac F.,
GarcíaSantos M. Pilar,
Calle Emilio,
Casado Julio
Publication year - 2009
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.1477
Subject(s) - chemistry , decomposition , sodium nitrite , solvent , inorganic chemistry , reaction rate constant , dissociation (chemistry) , sorbic acid , nucleophile , nitrous acid , acid dissociation constant , acidity function , medicinal chemistry , kinetics , organic chemistry , aqueous solution , catalysis , physics , quantum mechanics
A kinetic study of the decomposition reaction of 1,4‐dinitro‐2‐methylpyrrole (NMP) and ethylnitrolic acid (ENA), both formed in the reaction between sorbic acid and sodium nitrite was performed in the 3.5–4.2 pH range in water/dioxane mixtures. Conclusions were drawn as follows: (i) The decomposition of NMP occurs through nucleophilic attack by OH − ions, the rate equation being: r = k dec NMP [ OH − ][ NMP ]. (ii) The rate law for the decomposition of ENA is: r = $k_{dec}^{ENA}$ [ENA] K a /( K a + [H + ]), K a being the ENA dissociation constant. (iii) The value of K a decreases when the water/dioxane ratio decreases, log K a being proportional to the Onsager parameter (ϵ − 1)/(2ϵ + 1). This permits the equilibrium between non‐dissociated and the dissociated forms of ENA to be rationalized. (iv) No appreciable variation in the Δ H # and Δ S # values with composition of the medium was observed, either in the NMP decomposition reaction, or in the ENA decomposition reaction. Copyright © 2008 John Wiley & Sons, Ltd.