Kinetics and mechanism of peroxysulfate/NaNO2 mediated nitration of phenols in aqueous bisulfate medium

Abstract

Peroxy sulfates (PS) like peroxydisulfate (PDS), and peroxymosulfate (PMS) have been accomplished as an efficient reagents for KHSO 4 /NaNO 2 mediated nitration of aromatic compounds (S) such as phenols in aqueous bisulfate and acetonitrile medium, under the conditions [NaNO 2 ] ≫ [PS]. The kinetics of the reaction depicted first order dependence on [S], [NaNO 2 ], and [PS]. Reaction rates were sensitive to the introduction of electron donating or withdrawing groups. However, our efforts to correlate the kinetic results into Hammett's structure-reactivity equation were not fruitful. Observed deviations from the linearity of Hammett's equation have been interpreted in terms of effective Hammett's constants (σ or σ eff), para resonance interaction energy (ΔΔGp) values and Yukawa-Tsuno's resonance stabilization parameter (r). The observed negative magnitude of entropy of activation (∆S #) values suggests greater solvation and/or cyclic transition state before yielding products.

Phosphomolybdic acid hydrate encapsulated in MIL-53 (Fe): a novel heterogeneous heteropoly acid catalyst for ultrasound-assisted regioselective nitration of phenols

“…4,[9][10][11][12][13] The mechanistic studies show that these reactions proceed through a nitronium ion (NO 2 + ) which is attacked by p electrons delocalized around the aromatic rings leading to breakage of one of the N]O bonds to avoid a ve-valent nitrogen. [14][15][16] Although the nitration of phenol is also very fast, these methods are not selective for the direct nitration of phenol, producing a mixture of ortho-and para-nitrophenols. 1 Besides, dilute nitric acid must be used to avoid the oxidation and overoxidation of phenols to unspecied resinous products.…”

Synthetic Protocols for Aromatic Nitration: A Review

“…Mild condition, use of inexpensive and readily available green reagents makes this method eco-friendly. [52] Mathew and co-authors have developed an efficient reagent for ipso-nitration of aryl boronic acid using halotrimethyl silane and nitrate or nitrite salt (Scheme 44). Initially the sodium nitrate react with chlorotrimethylsilane formed trimethylsilylnitrate, which act as nitrating agent and further react with aryl boronic substrate to form nitro aromatic compound.…”

“…A variety of phenols with electron‐donating groups are smoothly nitrated by this method and gives good to excellent yields. Mild condition, use of inexpensive and readily available green reagents makes this method eco‐friendly [52] …”

Trichloroisocyanuric acid (TCCA) and carboxamide interactions in TCCA/NaNO2 triggered nitration of pyrrole and indole in aqueous aprotic media: A kinetic correlation of solvent properties with reactivity

“…In several protocols, we have either completely avoided or minimized the use of mineral acids. [4][5][6][7][8][9][10] In 1902, Chattaway and Wadmore 11 reported the use of trichloroisocyanuric acid (TCCA) as a versatile oxidizing and chlorinating laboratory reagent, which is economically cheap, environmentally safe, less toxic, and easily available. 12 On the other hand, there has been an upsurge in the use of N,N′-dimethylformamide (DMF) by physical organic and organic chemists, because it is a polar aprotic solvent and exhibits hydrophilic properties.…”

“…Ours is one among the several research groups, which has undertaken the development of certain protocols to achieve nitration by replacing an acid mixture. In several protocols, we have either completely avoided or minimized the use of mineral acids 4–10 . In 1902, Chattaway and Wadmore 11 reported the use of trichloroisocyanuric acid (TCCA) as a versatile oxidizing and chlorinating laboratory reagent, which is economically cheap, environmentally safe, less toxic, and easily available 12 .…”