Facile nitration of aromatic compounds using Bi(NO3)3·5H2O/MgSO4 under mechanochemical conditions

Abstract

Bi(NO3)3·5H2O/MgSO4 was developed as an efficient and green reagent for the nitration of aromatic compounds under mechanochemistry (or ball milling) condition. While aromatics with weak activating groups such as phenyl could be nitrated by this reagent with 100% conversion, aromatics with weak deactivating groups such as chloro- or bromo- could also be nitrated but with moderate conversion and regioselectivity with big para/ortho ratios. The in situ generated N2O4 or NO2 due to the decomposition of Bi(NO3)3·5H2O promoted by MgSO4 should be responsible for this mechanochemical nitration.

Selective oxidation of primary benzylic alcohols to aldehydes using NaNO3 under ball milling

“…First, NaNO 3 would react with P 2 O 5 to generate nitric acid, which could be decomposed to generate N 2 O 4 /NO 2 under the mechanical force, as described in our previous work. 27,28 Next, the in situ-produced N 2 O 4 /NO 2 should be responsible for the oxidation, most probably, following the radical-type mechanism reported by Nishiguchi and Strazzolini. 12,15…”

“…26 In our previous work in the area of mechanochemical synthesis, the combination of Bi(NO 3 ) 3 •5H 2 O and MgSO 4 was successfully employed for the nitration of aromatic compounds. 27 Recently, we reported that the combination of Fe(NO 3 ) 3 •9H 2 O and P 2 O 5 could convert deactivated arenes into the corresponding nitrated arenes in excellent yields under high-speed ball-milling (HSBM) conditions. 28 We proposed that the N 2 O 4 /NO 2 , which was produced in situ from the reaction of nitrates and the auxiliary, should play a major role in these mechanochemical nitrations.…”

Synthetic Protocols for Aromatic Nitration: A Review

“…Here, the authors used various activating and deactivating groups such as chloro, bromo, and carboxylic acid to obtain excellent to moderate yield. However, the plausible mechanism of this reaction not yet clear [42] …”

Recent Advances in Mechanochemical Organic Synthesis

“…C▬N bond forming reactions were paid larger attention to. Mechanochemical nitration reactions of aromatics are extended to various reagents: NaNO 3 in conjunction with MoO 3 as an additive [43], BiNO 3 with MgSO 4 [44], as well as BiNO 3 alone was applied for nitration of fullerene C 60 [45]. Amine guanylation with N,N′-Di-Boc-1H-pyrazole-1-carboxamidine [46] and facile Boc deprotection was achieved with TsOH [47].…”