3076
J. Org* &%em.,Vol, SY, No. 20, 1972 T
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STRAUSS, TAYLOR, AND REZNICK
Interactions of Electron-Deficient Aromatics with Amines, Addition to the Ring and t o a Ring Substituent M. J. STRAUSS,* S. P. R. TAYLOR, AND A. REZNICK Department of Chemistry, University of Vermont, Burlington, Vermont 06401 Received March @4,1971
The addition of Phenylhydrazine to the ring and to a nitro group in 1,3,&trinitrobenzene has been observed. Only addition to the nitro group occurs with 2,4,6-trinitrotoluene. This is the firvt confirmed observation of concurrent substituent and ring addition, and confirms earlier proposals. The nature of the interactions is discussed.
Reactions of electron-deficient aromatics with amines I n fact, an oxyhydroxylamine intermediate was rehave been of interest for a number of years, and a cently proposed to result from the interaction of TNB variety of different types of interactions have been and amines, but the product was quite unstable and identified.l-lz With aromatic amines, the most comcould not be isolated.6 monly observed product is a donor-acceptor or r -0 complex.'tz There is some evidence in one instance for formation of an aromatic amine u complex, but it was not is01ated.l~ Tertiary aliphatic amines also form donor acceptor complexes with electron-deficient aromatics if the solvent in which the precursors are mixed is t t p r o t i ~ . ~ JWith primary and secondary amines, there is substantial evidence for addition t o the It has been reported that phenylhydrazine adds to aromatic ring, resulting in stable covalently bonded 1-nitrocyclohexene to give the adduct I , I 6 and that r c o r n p l e ~ e s . ~ I~n' ~addition to these more commonly p-methylphenylhydrazine displaces a nitro group in observed interactions, anion radicals and aromatic 2,4,6-trinitrotoluene to give the rearranged substituanions have been proposed t o arise from the reaction tion product 1I.l' A mixture of trinitrobenzene and of amines and 1,3,5-trinitroben~ene.~~$~~ A proposal phenylhydrazine was reported to yield a 1: 1 adduct,l8 of amine addition to a nitro group in this latter aromatic but the nature of this interaction is unclear as the has recently been published.6 We report here a study of the reaction of 1,3,5- authors did not state which isomer of trinitrobenzene was used. trinitrobenzene (TNB) and 2,4,6-trinitrotoluene (TNT) with phenylhydrazine. This latter amine is of interest for several reasons. It possesses both aromatic and aliphatic amine character, and was expected to easily form both T and Q complexes. I n addition, attack of phenylhydrazine on a nitro group in TNB or T N T I II NHCGHE could lead to isolable triazene oxides or diazohydroxyI amino compounds. Similar reactions occur upon addition of phenylhydrazine to nitro~obenzenes,~~ It is well known that ortho dinitro substituted and the reducing action of phenylhydrazines on arobenzenes are prone to lose NOz- when attacked by ArNO t- ArN"Hz n ~ c l e o p h i l e s ~ 9 whereas -~~ polynitrobenzenes without ortho nitro groups can form reasonably stable charge -0 OH transfer or u complexes under similar condit'ion~.~ I H I Additi.on of 0.02 equiv (2.2 g) of phenylhydrazine Ar+N=NNAr r;t ArNN=NAr in 50 ml of benzene to 0.01 equiv (2.1 g) of TNB in 100 ml of benzene produces a yellow solution which matic nitro compounds to yield anilinesls suggests absorbs strongly below 400 mfi. This absorption dethat a similar addition might occur to the nitro group. velops instantaneously and probably results from a (1) R. Foster. "Organic Charge Transfer Complexes," Academic Press, charge transfer interaction as depicted in 111"22It Kew York, N. Y . ,1969. (2) L. J. A n d r e w and R. M. Keefer, ",Molecular Complexes in Organic is difficult to determine, , ,X as absorptions from uncomChemistry," Holden-Day, Ban Francisco, Calif., 1964. plexed phenylhydrazine and sym-trinitrobenzene over(3) E. Buncel, A. R. NorriB, and I
