IODINEAS h RADICAL DETECTOR IN HYDROC.~RBON RADIOLYSIS
Jan. 20, 19.57
Although no pure 6-HCC was recovered, the evidence for the presence of this isomer is fairly conclusive. The absence of all other HCC isomers has not been established. It is impossible to give a simple mechanism for the formation of the 6-HCC a t this time; however, two possibilities can be discussed. First, it is possible that 6-HCC is formed from the a-HCC previously produced from the r-HCC by the “flipping over” of chlorine 4. I t is also possible that the delta isomer is formed from the gamma directly. When one of the 2,G-biaxial chlorines is removed, chlorine 1 is in the proper trans position to form a bridge between carbons 1 and either 2 or G.13 A chlorine ion may then be picked up in either of two positions as illustrated
1
c1
I
AlClr
)C-$(
__t
AlC13
I
+
>Cc‘CC--C
J
c1
c1
beta
c1+ C1-
’
alpha ( MIRROR IMAGES
c1
1
AlClal C1-
-+
c1
>C!--C > R1 (and R1*), the (C14N-)/(CN-) ratio is the TABLE I EXPERIMENTAL AND CALCULATED APPARENT EQUILIBRIGM CONSTANTS FOR THE REACTION CNI C14NC"NI C S - AT 30.6'
+
Vol. % dioxane in solvent
0 20 28 40 40 40 60
No. of deReactant terratio minaf = a/b tions
0.9 .9 .9 .1
.9 12.2 0.9
12 22 22 8 40 12 22
e
KW (av. =tstd. dev.)
Kenid.
1.08 rt 0 . 0 2 1.15 .02 1 . 1 8 i: .03 1.15 =t , l o " 1 . 2 8 =t .02 1.63 & .11" 1 . 2 9 zt .03
1.086 1.l.5b 1.18h 1.23" 1.29" 1.58' 1.29'
+
Reac. rate ratio s = Ri*/Rz
0.19 0 . 75h 1.25'' Large Largc Large Large
Results and Discussion The values of K e x p obtained for a number of solvent compositions and a/b ratios are summarized in Table I. The reactions involved are
Errors greater in these instances since determination is much less precise forf values far from unity. * From Fig. 1, Calculated by eq. 2. curve E.
(1) A preliminary report was made of this work in THIS JOURNAL, 77, 4438 (1955). (2) F. E. Jenkins and G. M. Harris, t o be published. (3) D. R. Stranks a n d G. M. Harris, THISJOURNAL, 75, 2015 (1953). (4) I t was found impossible t o achieve this high a degree of reproducibility by means of the zinc cyanide precipitation procedure used b y Ariamson and co-workers ( i b i d . , 73, 4786 (1951); 74, 1590 (1952)).
same in the precipitate as in the original equilibrated aliquot of solution. Then Kexpas determined by eq. 1 is in fact the true equilibrium constant K = R,/RI". (2) If R1 (and Rl*) > > RB (and R2*), equilibrium is continuously maintained during precipi-
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