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Nucleophilic reactions of hexafluorob enzene and related polyfiuorobenzenes were studied in detail. R eaction of hex a fluorobenzc nc with hydroxides, alco holates, aqueous amines, and organolithium co mpounds led to the substitution of one 01' more fluorine atoms. The stru ctures of the products were determined, using near infra red a nd nuclear m agnetic resonance spectra. Fluorine is replaced more readily than chlorin e, bromine, iodine, or other groups. I n the ma jo rity of the products in which two of the fluorin es in hexafluorobenzene we re replaced, t he substituting groups were p a ra to eac h other. However, depe nding on the reagents other orientation effects were noted . The reaction mechanis ms we re a fun ction of reagents a nd co nditions. The mo t prcvalent mecha ni sm is presuma bly the di splace me nt of a fluoride anion by another anion, probably via the fo rmation of transition co mplexes of difl'erent lifetimes. Howeve r, simple ionization 0 1' attack by neutral species may occ ur under some co nditions. The diazotization a nd oxidation of pentafluoroan il ine were also inv estigated.

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3 ti50 NOTES Vol. 77 case the tautomeric equilibrium favors strongly the ketone structure 111.The ultraviolet spectrum of the cyclic product obtained from adiponitrile offers further evidence for the existence of an unusual, conjugated nitrile group since there is a major absorption peak a t 263 mp. Simple aliphatic nitriles do not absorb appreciably in this region, but conjugated nitriles and conjugated aminoesters (e.g., ethyl p-aminocrotonate) do absorb strongly a t about 265 mp.4The absorptivity (e) is 13,000 liters per mole-centimeter which is about 130 times as large as observed for normal conjugated nitriles; thus the ;mine group has a powerful effect on the ultraviolet absorption of this conjugated nitrile group. This is in concordance with the observations made on ethyl /3-atninocrotonate by Glickman and Cope,4 on p-aminocrotonitrile by \-on Xuwers and Suseinihl, and with the unusually low infrared nitrile frequency we have observed for IT.'. E. I. DU PONT DE SEMOURS 8r Co., I N C . Du P o w EXPERIMESTAL STATIO?: \VILMISGTOX, DELAWARE