4-Nitro-l,2-benzenediamine

Formation of diamines from dinitro compounds, which are unable to interact intramolecularly, presents no problem. Very large volumes of diaminotoluene, a precursor to toluene diisocyanate, are produced by hydrogenation of dinitrotoluene over either nickel or palladium-on-carbon. Selective hydrogenation of one or the other of two nitro groups is much more of a challenge, but a number of outstanding successes have been recorded. A case in point is the hydrogenation of 2,4-dinitroaniline (11) to 4-nitro-l,2-benzenediamine (12) (2) or to 2-nitro-l,4-benzenediamine (10). 

Nitro-l,2-benzenediamine (127) gave mainly 2-decyl-6-nitroquinoxaline (128) (CioH2iCCl2CHO H20-dioxane, pH 9, by NajCOsi, reflux, 2 h 34% after separation from a little of the 7-nitro isomer). 

Nitro-l,2-benzenediamine (152) and chloroacetonitrile (153) gave 6-nitro-3,4-dihydro-2-quinoxalinamine (154), apparently without 7-nitro isomer (Et3N, p-xylene, reflux, 6 h 47%). ... 

Nitro-l,2-benzenediamine (165) and l-methyl-2-phenylglyoxal (166) gave a mixture of 2-methyl-7-nitro- (167) and 2-methyl-6-nitro-3-phenylquinoxaline (168) (MeOH, reflux, min >70%), subsequently separated chromatogra-... 

Indolinedione (isatin 513) and 4-nitro-l,2-benzenediamine (512) gave 3-o-aminophenyl-6-nitro-2(177)-quinoxalinone (514) [AcOH, reflux until no... 

Methyl-1,2-benzenediamine (215, R = Me) with the hydrate of 3,3,3-trifluoro-pyruvic acid gave a mixture of isomers (216, R = Me) and (217, R = Me) (dioxane, reflux, 30 min 98%) from which neither appears to have been isolated in a pure state 165 in contrast, 4-nitro-l,2-benzenediamine (215, R = N02) and the same synthon gave a mixture of 6-nitro- (216, R = N02) and 7-nitro-3-trifluoromethyl-2(l//)-quinoxalinone (217, R = N02) (dioxane, reflux, 4 h 95%), from which both isomers were isolable, albeit with considerable loss.165... 

Fig. 12. Structure of 4-nitro-l,2-benzenediamine [18]crown-6 complex 22) a a perspective view, b as viewed almost perpendicular to the plane of the crown, hydrogen bonds marked with dotted lines...

Although derivatives of 2,1,3-benzoxadiazole have been used extensively to make quinoxalines (see Section 1.6.7), the corresponding selena and thia systems have been paid scant attention for that purpose. However, 5-chloro-4-nitro-2,l,3-benzoselenadiazole (456) has been used as a convenient source of 4-chloro-3-nitro-1,2-benzenediamine (457) (HCl + HI, 20°C, 2 h 88%), which was then converted into 6-chloro-5-nitro-2,3(l//,4//)-quinoxalinedione (458) (oxalic acid, 2M HCl, reflux, 2.5 h 23%). ° In addition, irradiation of 2,1,3-benzoselenadiazole (460, X = Se) or 2,1,3-benzothiadiazole (460, X = S) with dimethyl acetylenedicarboxy-late afforded, among other products, dimethyl 2,3-quinoxalinedicarboxylate (459)... 

The valuable synthetic intermediates are benzo-2,l,3-selenadiazoles. They were used for preparation of. V-al ky I-1,2-benzenediamines, 3-nitro-1,2-benzenediamines, 3,4-diamino-2-nitrophenols, and 5-nitroqunoxalines. The key step of the reaction is their reductive deselenation with hydrogen iodide or, better, with ammonium hydrosulfide [233-238],... 

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