Kinetics of Aromatic Nitration

Abstract

Heterogeneous nitration rates of the aromatic organic compound 1, 3-bis(trifluoromethyl)benzene in a well-agitated batch system have been measured in an extensive range of very concentrated mixed acids (aqueous HN0 3 and H 2 SO 4), with each run at essentially constant acid composition. The observed conversions correlated well with a firstorder dependence on the fraction of aromatic unconverted. Solubilities of the aromatic compound have been measured over the range of acid compositions.

Evidence from the Rate of Homogeneous Nitration of Hexafluoro-m-xylene for Kinetic Control in the Two-Phase Reaction

“…In an attempt to throw light on the kinetics of two-phase aromatic nitration, Miller et al (1964) carried out a study of the heterogeneous nitration of l,3-bis(trifluoromethyl)benzene or hexafluoro-m-xylene. They chose this compound because (a) it forms only one nitration product, (b) it is similar to many aromatics in being only sparingly soluble in mixed acid, and (c) it is extremely resistant to nitration, thus allowing high acid concentrations to be employed and investigated.…”

“…For if the heterogeneous rate is kinetically controlled, Ra/XA should be equal to &2[HN03][A]aa or fia/XA[A]aa should be equal to /e2[HN03], where k2 is the second-order homogeneous nitration rate constant and [HN03] is the moles per liter concentration of nitric acid in the aqueous phase. It was with the purpose of obtaining fe2[HN03] values from homogeneous studies for comparison with fia/XA[A]as values from the heterogeneous studies of Miller et al (1964) that this work was undertaken.…”

Safety enhancement by transposition of the nitration of toluene from semi-batch reactor to continuous intensified heat exchanger reactor

“…This acid mixture is the most common nitrating system currently adopted in chemical industry (Miller et al, 1964;Harris, 1976). The main reaction is the mononitration characterized by a heat of reaction H r of −125 kJ mol −1 (Chen and Wu, 1996):…”

Prussian Blue/NaNO2as an Efficient Reagent for the Nitration of Phenols in Aqueous Bisulfate and Acetonitrile Medium: Synthetic and Kinetic Study

“…The existence of nitronium ion (NO + 2 ) species has been further confirmed by x-ray crystallography and Raman spectroscopic studies [24][25][26]. Research reports of Kecki [29] and Miller et al [30] furnished excellent literature and a detailed account of the role of acidity in the nitration of aromatic compounds from detailed kinetic studies. In another review, Kulkarni [31] highlighted four different approaches for continuous flow of nitration with microreactors.…”

“…On the other hand, several kinetic and instrumentation studies have been taken up to understand the mechanism of nitration since the 1904 , which provided ample of evidence for the formation of nitronium ion (). The kinetic studies taken up by Ingold's research group and Martinsen contributed enormously to understand the role of nitronium () and nitracidium (H 2 NO 3 + ) ion species in the mechanism of nitration under different conditions.…”