Nitrocarbons. 4. Reaction of Polynitrobenzenes with Hydrogen Halides. Formation of Polynitrohalobenzenes

Article abstract of DOI:10.1021/jo00198a001

Hexanitrobenzene and pentanitrobenzene in benzene solution react with hydrogen halides (HCl, HBr, HI, but not HF) at 25 deg C to produce high yields of pentanitrohalobenzenes and 2,3,4,6-tetranitrohalobenzenes, respectively.Pentanitrofluorobenzene also reacts readily with HCl to yield 3-chloro-2,4,5,6-tetranitrofluorobenzene, but the other pentanitrohalobenzenes are much less reactive. 1,2,3,5- and 1,2,4,5-tetranitrobenzenes react rapidly with concentrated hydrochloric or hydrobromic acids at reflux to form picryl halides and 1-halo-2,4,5-trinitrobenzenes, respectively; pentanitrotoluene reacts very slowly under these conditions to form 3-halo-2,4,5,6-tetranitrotoluenes in lower yields.The scope and limitations of this regioselective reaction are defined, and comparison is made to related reactions.A mechanism is presented and discussed.