COMMUNICATIONS TO THE EDITOR
Oct. 20, 1960
5513
rule is applicable in situations where only secondorder effects are operative.
The perfluoroheptylation of benzene provides a n illustration of the general procedure. Perfluoroheptyl iodide was prepared by the method (6) Support by the Alfred P. Sloan Foundation is gratefully acof Brice and Simonsa; i t had b.p. 138.5’ and n Z 5 D knowledged. ( 7 ) Trubek Fellow, 1958-1959; N.S.F.Cooperative Fellow, 19591.3274. 1960. Anal. Calcd. for C7F151; C, 16.95; F, 57.46. (8) Trubek Fellow, 1959-1960. DFPARTMENT O F CHEMISTRY KURT MI SLOW^ Found: C, 17.1; F, 58.1. ROBERT E. O’BRIEN’ NEWYORKUNIVERSITY Into a 43 ml. Aminco stainless steel autoclave NEWYORE53, N. Y. HANSSCHAEFER~ was placed 26.0 g. (0.052 mole) of w - C ~ Fand ~ ~ 2.1 I RECEIVED AUGUST15, 1960 g. (0.027 mole) of benzene. The autoclave was sealed, a 3000 psi.-nickel rupture disk being employed, and the contents were heated for 15 hours PERFLUOROALKYLATION OF AROMATIC COMPOUNDS a t 250°, then chilled to 0’. The autoclave was Sir : opened cautiously and rinsed out with 50 ml. of ~ 0 ~55’), the free iodine remaining While trifluoromethyl-substituted aromatic com- c y ~ l o - C ~ F 1(b.p. undissolved. The solution was fractionally dispounds are well k n ~ w n , ’ and ~ ~ ’certain ~ ~ ~ ~per~ fluoroethyl- and perfluoropropyl-substituted ben- tilled through a 10-cm. Podbielniak “Heli-pak” of zenes have been obtained by much more lengthy column. There was obtained ’7.2 g. (f~27~70) ~ and 2.8 g. syntheses,3 , 4 , 5 no procedure has been available for n-C7F15C6H5,b.p. 200°, n Z 5 1.3576, 270°, C~H ~ , m.p. 88’ the direct introduction of perfluoroalkyl groups (26%) of ( w - C ~ F ~ ~ ) ~b.p. into aromatic nuclei. It is thus of particular im- (after recryst. from c ~ c ~ o - C ~ F ~ ~ O ) . portance to report a very general new reaction for Anal. Calcd. for CI3H6F15: C, 34.99; F, 63.88. the perfluoroalkylation of aromatic compounds, Found: C, 35.0; F, 64.0. Calcd. for C20H4F30: based upon free-radical substitution of aromatic C, 29.50; F , 70.00, Found: C, 29.5; F, 69.9. hydrogen, which appears to be limited in scope When twice as much benzene was used, disubonly by the stability of the aromatic compound stitution was reduced to 8% but the yield of nionounder the rather strenuous reaction conditions. The course of the reaction is indicated by the substituted product was not improved substantially. The infrared spectra of such compounds are unequation usually difficult to interpret, owing to the exceed350° ArH 2RfI ---+ Rr-Ar RfH + 1% ingly strong bands contributed by the perfluorowith yields of 60 to 65% commonly being attained; alkyl groups in the “fingerprint region” which disubstitution also occurs, the corresponding yield ordinarily is highly characteristic for aromatic rising as high as 2570 when no excess of aromatic derivatives. Retention of the benzenoid structure compound is present. A wide variety of aromatic is confirmed by ultraviolet spectroscopy, electrohydrocarbons and their derivatives have been philic bromination and nitration, and especially perfluoroalkylated successfully, examples being by proton and fluorine nuclear spin resonance specbenzene, toluene, naphthalene, halobenzenes, per- troscopy. I am particularly indebted to B. W, Nippoldt fluoroalkylbenzenes, benzonitrile, phthalic anhyarid P. B. Olson for elementary analyses, and to dride, even fully formed dyes. Dr. W. E. Keiser and Dr. John McBrady for in(1) J. H. Simons, ed., “Fluorine C hepistry,” Academic Press, frared spectroscopy. New York, N. Y., Vol. I, lQ60,pp. 494-498 and 506-513; Vol. 11,
+
+
1964, pp. 220-223. (2) R. N. Haszeldine and A. G. Sharpe, “Fluorine and its Compounds,” Methuen and Co., Ltd., London, 1951, pp, 116-126. (3) E. T.McBee and 0. R. Pierce, I n d . Eng. Chcm., 39, 397, 399 (1947). JOURNAL, (4) E. T.McBee, C. W.Roberts and A. F. Meiners, THIS 79, 335 (1457). (5) W. R. Hasek W. C. Smith aud V. A. Engelhardt, i b i d . , 82, 543 (1960).
CONTRIBUTION No. 182 FROM THE CENTRAL RESEARCH DEPARTMENT OF T H I ~ MINNESOTA MINING& MFG.Co. GEORGEV. I). TIKRS ST PAUL19. MINN. RECEIVED SEPTEMBER 12, 1960 (6) T. J. Brice and J. I€. Simons, U. S. Patent 2,614,131 (1952). ( 7 ) T. J. Brice and K. I. Coon. THIS JOURNAL,7 6 , 2921 (1953).
