Vol. 78
COMMUNICATIONS TO THE EDITOR
5696
GH RCOO
w
VI11
+ Ho :
ESTE R(S)
VI
TRANS - DIESTER(S)
Inversion
H
CIS-HYDROXY
e
CIS - DIESTER(S)
H
I
VI1
-0-R'
R
IV R' = H, V R' = RCO-
159-160") m.m.p. 169-160". trans-1,3-Cyclopen- Utilizing Mosher's p o ~ t u l a t e ,RC02e ~ (11) or its tanediol'b also was obtained from the cleavage mix- equivalent, we account for the formation of I11 by ture as the di-p-nitrobenzoate, m.p. 184-185", re- attacks of I1 on CPD and for glycolic ester formaported?m.p. 186" and the diurethan, m.p. 172-173") tion by attack on the a-position of the diesters. reported? m.p. 173". Oxidation in anhydrous acetic Evidence of free radical attack was not f ~ u n d . l ~ . ~ acid gave cis and trans-3,4-diacetoxycyclopentene ,4n Armstrong Cork CO. Fellowship (F. J. V.) (37'%), proven as before. and a du Pont Co. Summer Faculty Fellowship Oxidation in dry acetic acid with one equivalent4 (F.V.B., Jr.) are gratefully acknowledged. Of potassium acetate added gave "% Of a product (8)Other ionic paths are under consideration. The 3,5-by-prodshown later by periodic acid titration t o be 97% U C t S may arise from a 3,5-cation, similar to 111, trans-3,4-diacetoxycyclopentene, b.p. 85" a t 1 mm. (9) M . s. Kharasch, H. N. Friedlander and w. H. Urry, J . Org. (Anal. Calcd. for CgH1204: C, 58.68; H, 6.57. Chem., 16, 533 (1951). Found: C, 58.85; H, 6.75), transformed similarly DEPARTMENT OF CHEMISTRY t o trans-l,2-di-p-nitrobenzoxycyclope~~~~e, m.p. HARRISON LABORATORY FREDERICK V. BRUTCHER, JR. FULVIO J. VARA 143-145") m.m.p. 143-145'. I n addition, a 3% yield of triester was obtained which was hydrolyzed t o RECEIVED AUGUST1, 1956 trans-3,4-cyclopentenediol and potassium glycolate.la Reaction of lead tetrabenzoate and CPDl'f: in AFFINITIES OF ETHYLENE, TETRAFLUOwet benzene gave a sufficient amount of benzoic METHYL ROETHYLENE AND TETRACHLOROETHYLENE' acid and a non-crystalline cis-hydroxybenzoate (41y0) transformed similarly to give cis-l-benzoxy- si7: I n the course of our studies of methyl affinities of 2-~-nitrobenzoxycyclopentane (64%)) m.p. 88-89' (Anal. Calcd. for CI9H1706N: C, 64.23; H, 4.82; aromatic and olefinic compounds we determined N, 3.04. Found: C, 64.13; H, 4.63; N, 3.91) and the relative rates of addition of methyl radicals to ethylene, tetrafluoroethylene and tetrachloroethylto give I, xn.p. 116-11S0, m.m.p. 116-118". I n interpreting this, we invoke a Winstein neigh- ene. The results obtained demonstrate some funboring ~ a t i o n111, , ~ which opens cis with water (I11 damental principles governing the rate of radical addition reactions thereby deserving further dis+ 1V + VI) or carboxylic solvent (111 + V + VII) and trans with carboxylate anion (I11 +- VIII) cussion. The methyl affinities are determined by a method utilizing the reactivity sequence, H20 > RCO,e > described e l ~ e w h e r e , ~and * ~ , ~represent the ratio RC02H. I n Criegee's experiments, the stereochemistry of kz/'kl. the 1,2-products was controlled by traces of water (1) This work was supported by a grant from the XCational Science until consumed (I11 + I V + VI), then by carbox- Foundation. (2) M . Szwarc, J Po'olymcr Sci., 1 6 , 367 (1955) ylic solvent (I11 + V + VII) until the effective (3) M. Levy and M Szwarc, THISJ O U R N A L , 7 7 , 2193 (1955). anion concentration from divalent lead salts be( 4 ) F Leavitt, M. Levy, A t . Siwarc and V Stannett, i b i d , 71 came dominant (I11 + VIII). 5493 (1955).
~~~~~~~~~::4~syL~.AN1A
COMMUNICATIONS TO THE EDITOR
Nov. 5, 1956 CHs CH,
+ isooctane +CHI + isooctyl radical
+ olefin +olefinCH8
k1
4,
- E1 - E1
= -0.6 kcal./mole
A ~ / A I= 13.0
= -2.8 kcal./mole
A2/A1 = 5.3
The reactivity of tetrachloroethylene is too low to determine the activation energy with any reasonable accuracy. We conclude t h a t the reactivity of tetrafluoroethylene is approximately ten times greater than t h a t of ethylene, while tetrachloroethylene is unreactive. The higher reactivity of tetrafluoroethylene is shown to result from the lower activation energy of the addition reaction (as compared with ethylene), while the AZ/A1 factor is lower for the reaction involving tetrafluoroethylene than that for ethylene. The methyl affinity of ethylene is comparable to that of vinylacetate, is approximately 80 times greater than t h a t of benzene and l / 2 6 as large as that of styrene. TABLEI Compound
T, ‘C.
kdki
Ethylene Ethylene Ethylene Ethylene Tetrafluoroethylene Tetrafluoroethylene Tetrafluoroethylene Tetrafluoroethylene Tetrachloroethylene
54.7 64.9 74.8 85.2 54.7 64.9 74.8 85.2 64.9
37 3 f 0.6 34.1 f 2 . 2 34.6 f 0.6: 35.5 f 1 . 5 400 f 7 342 f 14 307 rt 8 273 f 8
