Nitration of aromatics with dinitrogen pentoxide in a liquefied 1,1,1,2-tetrafluoroethane medium

Abstract

A green, safe, and economical method for the production of nitroaromatics is developed. The method comprises the use of the eco-friendly nitrating agent, dinitrogen pentoxide, and liquefied 1,1,1,2-tetrafluoroethane as the reusable reaction medium.

Trifluoromethanesulfonic Acid Promoted Controllable Electrophilic Aromatic Nitration

“…Using general procedure A, 1,4-dichlorobenzene (147 mg, 1 mmol) was used as the substrate. Compound 2f was isolated as a white solid (190 mg, 99% yield) after flash chromatography (10/1 petroleum ether/ethyl acetate): 1 H NMR (400 MHz, CDCl 3 ) δ 7.88 (s, 1H), 7.51 (s, 1H), 7.50 (s, 1H); 13 C­{ 1 H} NMR (101 MHz, CDCl 3 ) δ 148.2, 133.5, 133.3, 132.9, 125.7, 125.6 …”

“…Additionally, there is a serious safety risk in the actual production due to the high temperature and sometimes accompanying side reactions because of the strong oxidability of concentrated sulfuric acid. Dinitrogen pentoxide (N 2 O 5 ), the anhydride of HNO 3 , an effective and eco-friendly nitrating agent, was also being used in the electrophilic aromatic nitration reactions . Recently, novel methods were developed to synthesize nitro-aromatics, such as transition-metal-catalyzed C–H nitration and the nitration of aryl boronic acids, aryl halides and pseudohalides, and aryl carboxylic acids .…”

“…Dinitrogen pentoxide (N 2 O 5 ), the anhydride of HNO 3 , an effective and eco-friendly nitrating agent, was also being used in the electrophilic aromatic nitration reactions. 6 Recently, novel methods were developed to synthesize nitro-aromatics, such as transition-metalcatalyzed C−H nitration 7 and the nitration of aryl boronic acids, 8 aryl halides and pseudohalides, 9 and aryl carboxylic acids. 10 Meanwhile, new and mild nitrating reagents were applied to the nitrating reactions.…”

“…Compound 2f was isolated as a white solid (190 mg, 99% yield) after flash chromatography (10/1 petroleum ether/ethyl acetate): 1 H NMR (400 MHz, CDCl 3 ) δ 7.88 (s, 1H), 7.51 (s, 1H), 7.50 (s, 1H); 13 C{ 1 H} NMR (101 MHz, CDCl 3 ) δ 148.2, 133.5, 133.3, 132.9, 125.7, 125.6. 6 1,4-Dimethyl-2-nitrobenzene 2g. Using general procedure A, 1,4dimethylbenzene (123 mg, 1 mmol) was used as the substrate.…”

Acid-Free Copper-Catalyzed Electrophilic Nitration of Electron-Rich Arenes with Guanidine Nitrate

“…Thus, aromatic nitration, which is an integral part of understanding the reactivity of aromatics in the organic chemistry curriculum, is among the most extensively studied chemical reactions . Mixed acid, a mixture of concentrated nitric and sulfuric acids, is widely employed in traditional electrophilic aromatic nitration. , Subsequently, other nitrating systems such as NO 2 + BF 4 – , NO 2 + PF 6 – , Crivello reagent (NH 4 NO 3 -TFAA), [Dsim]­NO 3 , N 2 O 5 , and N -NO 2 transfer reagents have also been used to achieve the nitration of arenes. These protocols were limited by some drawbacks such as employing strong acids and/or requiring pre-prepared nitrating reagents.…”