Regioselective and green synthesis of nitro aromatic compounds using polymer‐supported sodium nitrite/KHSO₄

Abstract

Polymer supported reagents have become the subject of considerable and increasing interest as insoluble materials in the organic synthesis. Use of polymeric reagents simplifies routine nitration of aromatic compounds because it eliminates traditional purification. In this article, the use of readily available cross-linked poly(4-vinylpyridine) supported sodium nitrite, [P 4 -Me] NO 2 , as an efficient polymeric nitrating agent in the presence of KHSO 4 is described. A good range of available aromatic compounds were also subjected to nitration in the presence of [P 4 -Me] NO 2 /KHSO 4 . This reagent is regioselective and chemoselective nitrating polymeric reagent for activated aromatic rings. In this procedure, the work-up is easy, and the spent polymeric reagent is easily regenerated and reused.

Diazotization–cyanation of aromatic amines with crosslinked poly(4‐vinylpyridine)‐supported cyanide ions

“…It is important to note that this polymeric reagent was stable and could be stored for a long time (months) without losing its activity; it could be readily used for the diazotization–cyanation of anilines. [P 4 ‐VP]I was recently prepared and used for the preparation of other functionalized polymers, including polymer‐supported thiocyanate, polymer‐supported carboxylate, polymer‐supported potassium ferrate, polymer‐supported azide ion,51 and polymer‐supported nitrite ion 46–50. Although [P 4 ‐VP]I is well known, [P 4 ‐VP]CN was used the first procedure for the direct diazotization–cyanation of aryl amines, and on the basis of our knowledge, there has been no report in the literature on the synthesis of aryl nitriles based on polymer‐supported cyanide ion.…”

“…Although polymer‐supported reagents, especially anion‐exchange resins, have been widely applied in organic synthesis,34–52 to the best of our knowledge, there has been no report on the synthesis of aryl nitriles via a dediazoniation–cyanation reaction based on polymer‐supported cyanide ions. Very recently Harrison and Hodge52 reported the synthesis of alkyl nitriles from alkyl halides with the Amberlyst A 26 CN − form.…”

“…Recently, we prepared crosslinked poly(4‐vinylpyridine)‐supported nitrite ions and examined their application in organic transformation, such as in the synthesis of nitro alkanes from alkyl halides,43 azo chromophores,46, 47 N ‐nitrosation of secondary amines,44, 45 nitration of aromatic compounds,48, 49 diazotization–iodination of aromatic amines (Sandmeyer type reaction),50 and diazotization–azidation of aromatic amines 51. In some of these studies, arenediazonium salts were generated in situ .…”

An efficient method for nitration of aromatic compounds over solid acid and polymer‐supported sodium nitrite

“…In continuation of our studies on application of crosslinked poly(4-VP)-supported sodium nitrite in organic synthesis, [47][48][49]52,53 herein we report a green, clean, and simple method for nitration of activated aromatic compounds using crosslinked poly(4-VP)supported hydrochloric acid, [P 4 -VP]HCl in the presence of [P 4 -VP]NO 2 or NaNO 2 . In this regard, a number of different reaction conditions for generation of HNO 2 with relatively strong organic acidic resins and [P 4 -VP]NO 2 or NaNO 2 for nitration of aromatic compounds was investigated.…”

“…[15][16][17] 18,37,38 Although there are numerous applications of solidsupported reagents and scavengers in literature, [39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58] but to the best of our knowledge, there is only one report 53 on the nitration of aromatic compounds using polymer-supported nitrating reagents. Recently, we prepared poly(4-vinylpyridine) (VP) crosslinked with 2% divinylbenzene (DVB)-supported sodium nitrite, [P 4 -VP]NO 2 , and poly(4-VP) crosslinked with 25% DVB-supported hydrochloric acid, [P 4 -VP]HCl, which was used for synthesis of nitroalkanes, 47 N-nitrosation of secondary amines, 48,49 synthesis of nitroaromatic compounds by [P 4 -VP]NO 2 /KHSO 4 , 53 and synthesis of azo chromophores.…”