Bromination of deactivated polycyclic aromatic nitro compounds

Competition of Aromatic Bromination and Nitration in Concentrated Sulfuric Acid

“…4,5-Dichloronitrobenzene 4 converted completely to 4,5-dichloro-1,3-dinitrobenzene 5 but not to 3-bromo-4,5-dichloronitrobenzene 6a. Compounds 6a manages to be obtained from dichloronitrobenzene 4 with bromine in sulfuric acid using other oxidizer instead of nitric acid, in particular hydrogen peroxide or potassium iodate [9]. Similar but with double quantity of bromine 3,5-dibromo-4-chloronitrobenzene 6b can be obtained from 4-chloronitrobenzene 3b.…”

“…It requires very hard conditions, for example heating in mixture of oleum and fuming HNO 3 at 140˚C -150˚C during one week [13]. Addition of bromine into nitrating mixture and heating a few hours at 60˚C -80˚C lead to 5-bromo-1,3-dinitrobenzene 2a in excellent yield [9,14]. Similarly 4-substituted 1,3-dinitrobenzenes 1b-d turn into 5-bromo derivatives 2b-d.…”

“…Product of reaction of 4,5-dichloronitrobenzene 4 did not contain bromine and was identified as 4,5-dichloro-1,3-dinitrobenzene 5. Compounds 6a and b were synthesized from 4 and 2b correspondingly using hydrogen peroxide instead of nitric acid [9]. Structures of the products were confirmed by comparison of their spectral data and physical constants with those of authentic samples.…”

“…They are bromine and silver sulfate [5] or trifluoromethanesulfonate [6] in sulfuric acid, N,N'-dibromocyanuric acid in sulfuric acid or oleum [7], bromine and BrF 3 in chloroform [8]. We have found a simple method for brominetion of strongly deactivated aromatic compounds by the action of bromine in concentrated sulfuric acid in the presence of nitric acid or some other oxidizing agent [9]. More recently bromination of deactivated aromatic compounds with sodium bromine and sodium periodate in sulfuric acid is reported [10].…”

“…4-Bromo-2,7-dinitro-9,10-phenanthrenequinone (9 Products of bromination of phenanthrenequinone 11 were separated by column chromatography. Compound 10 was isolated as the first fraction in yield 26% and compound 9 as the second fraction in yield 39%.…”