2,6-Bis(phenylamino)-4-(iminophenyl)benzoquinone

Abstract

The reaction of 2,4-difluoronitrobenzene with an excess of aniline at 175 °C led to the isolation of an unexpected brown quinone substituted with two phenylamino groups and one phenylimino group. This product was easily distinguished from other expected derivatives because it is brown rather than yellow. The UV/Vis has a weak long wavelength absorption at 480–600 nm accounting for the colour.

Uncovering John Holliday’s industrial dye synthesis patented in 1865

“…The reaction of nitrobenzene with aniline under basic conditions has been studied since this time but under these conditions, products were characterised. 26,27 Holliday’s reaction was repeated by us, and we isolated a red and blue product albeit in very low yield (Scheme 3). The samples were pure and gave good mass spectral data.…”

“…There is literature precedent for the formation of compounds 11 and 13 with these reagents and basic catalysis. 26,27 The difficult step is the reduction of compounds 11–13 to form compound 3 . However, traces of compound 3 might have been formed by this or by a similar mechanism and this may be the reason why Holliday’s synthesis gave low yields of products and was not commercialised.…”

Reactions of 4,5-difluoro-1,2-dinitrobenzene with amines in dimethylformamide or EtOH

“…The reaction of aniline with 2,4-difluoronitrobenzene 1 gives a low yield of 2,4-bis(phenylamino)nitrobenzene 2 1,2 and 2,6-bis(phenylamino)-4-(iminophenyl)benzoquinone 3 (Scheme 1). 3 Compound 2 forms a crystalline host having hydrogen bonded hexamers enclosing large one-dimensional channels, which makes them organic zeolites. Using two different amines in sequence, butylamine then 1,4-diaminobutane, or butylamine then piperazine, a dimer 4 or 5 was formed, respectively.…”

“…A literature survey of some reactions of fluorinated and nitrated aromatic compounds with amines. 1–11 …”

“…A literature survey of some reactions of fluorinated and nitrated aromatic compounds with amines. [1][2][3][4][5][6][7][8][9][10][11] Scheme 2. Some commercially available nitrated fluorobenzenes.…”