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4064
1D with 1E) is as expected, since urea is known to destabilize micelles (see footnote 9 and references contained therein). Thus the effects of solvent variables on the fluorine
spectra not only reveal pH- and urea-induced conformational changes, but they also help confirm the assignment of the resonances to fluorines in micelle-like and solvent-like environments.
C O M M U N I C A T I O N S TO T H E E D I T O R
Electron Spin Resonance Signals of Abnormal Alkyl Radicals Trapped on Porous Vycor Glass Surfaces Coated with Metal Oxides a t 77°K
Taking advantage of the spectral sensitizing propert)y of the PVG coated with VzO; (PVG(V20,)), we have Normal CH3CH>Radical
Publication costs assisted by the Faculty of Pharmaceutical Sciences, The University of T o k y o
Sir: As has been reported previously,1,2the normal and abnormal methyl radicals (CH8(1), g = 2.003, = 23.0 G; C&(II), g = 2.002, A H c ~ z s ( ~ ~ ) = 19.3 G) have been trapped on the surface of porous Vycor glass (PVG, Corning KO.7930) by the photolysis of adsorbed methyl iodide and methane a t room temperature and a t 77"K, respectively. Although there I l has been much interest in the adsorbed states of methyl - ~ pure signal of radicals on various solid s ~ r f a c e s , ~the the abnormal perdeuteriomethyl radical CD8(II) has not yet been observed owing to the larger line width and to the overlapping of the signals of both methyl Abnormal C H ~ C H ZRadical radicals. Quite recently, we have found that the presence of a very small amount (adsorbed fraction 0 = lov3 of certain metal oxides, such as Vz05 and 14003, on the surface of PVG exhibits a spectral sensitization to the formation of the CHS(I1) radical from methane at 77°K.6
l
-
Normal CD3 Radical
Abnormal CD3 Radical
L
I
1,
I
I
I
Figure 2. The esr signals of normal and abnormal ethyl radicals trapped on the surfaces of PVG(VzO5) at 77°K.
9.2602
I
& ---. A'= 3.5G
A .--. A0=3.0G
Figure 1. The esr signals of normal and abnormal perdeuteriomethyl radicals trapped on the surfaces of PVG's coated with VZOsa t 77°K. The Journal of Physical Chemistry, Val. 76, N o . 26, 1971
(1) J. Turkevich and Y. Fujita, Science, 152, 1619 (1966). (2) K. Shimamoto, Y . Fujita, and T. Kwan, B u l l . Chem. Sac. Jap., 43,580 (1970).
(3) G. B. Garbutt and H. D. Gesser, Can. J . Chem., 48,2685 (1970). (4) C. L. Gardner and E. J. Casey, ihid., 46,207 (1968). ( 5 ) G. B. Garbutt, 13. D. Gesser, and M.Fujimoto, J . Chem. Pltys., 48, 4605 (1968).
(6) Y. Fujita, K. Hatano, M. Yanagita, T. Kntsu, 31. Sato, and T. Kwan, B u l l . Chem. Sac. J a p . , 44, 2884 (1971).
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been able to observe a strong and well resolved esr signal of the abnormal deuteriomethyl radical CDz(I1) (g = 2.002, A D ~ ~ a= ( 3.0 ~ ~G) , A H ~ ~ 8 ( ~ ~ ) / =A D 6.5) without overlapping with the normal CD3(I) (g = 2.003, A D ~ ~ I ( ~3.5 ) G, A * C H ~ ( I ) / A ~ C D=~ ( I ) 6.5). The esr signal of the CD3(II)is shown in Figure 1 along mith that of the CDz(1). Experimental methods were similar t o those of previous reports.2r6 This technique to obtain the pure and large signal of abnormal methyl radical has been extended to the photolysis of homologous alkyl hydrocarbons at 77"1
