fling in the process by which cyclic phthalate is formed from peroxide and olefin. ll-e see no plausible path for isotopic shuffling in the process of formation of peroxide and exclude the first possibility on this basis. Earlier work3 has shown that the lactonic ortho-ester I1 and cyclic phthalate I have high thermal stability and are izot interconverted, excluding the second possibility. T h e third possibility represents an interconversion that might take place by way of an ion-pair process ( a ) or a molecular S N i process (b). Although
the reaction of phthaloyl peroxide with carboncarbon unsaturation. Experimental Phthaloyl Chloride-018.-A mixture of 11 g . of phtlialoyl chloride (Eastman Kodak 01. white label, redistilled, b . p . 86-88" a t 0.1 r n m . ) and 100 nil. of water containing 1.1 :itom c; ox>-gen-18(Stuart Oxygen Co.) w a s heated a t rcflus in-ernight. From the cooled mixture 9.4 g. of phthalic acid was obtained, dec. 11. 207-208". This inaterial was converted to phthaloyl chloride-0'8 by nie;ins of phosphorus pentachloride. Phthaloyl peroxide-coiboiz~l-0'" was prepared from thc above acid chloride by the procedure described previously. Reaction of Phthaloyl Peroxide-carbonyZ-018 with transStilbene.-This reaction was carried out under two sets of conditions. The oxygen-18 analyses are reported in Table
I.
s\y neither of these possibilities is excluded by the evidence a t hand, the resistance of simple esters t o this type of i n t e r c o n ~ e r s i o nand ' ~ the slowness of isomerization of tosylates under conditions t h a t are f a r more conducive to ionization" do not lend encouragement to the acceptance of alternatives a or b as the mechanism of oxygen transposition.';' On the other hand, isotopic shuffling in the olefin reaction itself is consistent with kinetic and product evidence.' This matter will be discussed in detail in a forthcoming publication in conjunction with additional information bearing on the mechanism of (13) 6. B. \Tiberg, T. 1%'. Shryne and R . R . Kintner. THISJ O U R X A L , 79, :3l(iO (19Z7). (14) D . B. Denney a n d B. Goldstein, ibid., 79, 4918 (1957). ( 1 5 ) Although processes of t h e t y p e a and b are consldered unlikely under t h e experimental conditions employed here, these processes m a y occur under other circumstances.
By Direct Reaction.--Peroxide :ind olefin were heated a t reflux in carbon tetrachloride f(ir 16 h r . anti worked u p 21s descrihed p r e v i o ~ s l y . ~The cyclic phthalate melted a t 206207' after recrvstallizatioxi from carbon tetmchloritlc (reported3 m.p. 206-21)i'0). .Alkaline hydrolysis of the cyclic plitliahte3 :tff(irdcd d1,2-diplien\.letlianediol o f 1n.p. 119.5-120" after recr1.stalliza-titinn from hexane. solutitm After Prior Heating of Phthaloyl Peroxide.-.\ o f 1.OO E. of uhthalovl Deroxide-cai.bonvl-Ol6 in 100 1111. of carbon tetraciiltiride k a i sealed in a flask under nitrogen and heated a t 80" for 96 lir. Iodometric analysis nf a 5ml. aliquot indicated oniy 137; destruction of peroxide in this time period. T:I the remainder o f the phthaloyl pcroxide solution TWS added :in equimol:ir amount of transstilbene, and the sr>lutiiin was heated a t reflux for 18 h r . .-I &mi. piirtiiin KIS evap(ir;tteti to dryness for spcctral :inalysis. The infrared ahsiirption spectrum o f this xtmplc in clilriroform was the s i m e a s t h a t iihtained Ixeviously from direct re:iction of the peroxide ant1 frans-stilbeiie.3 The cyclic phthalate was isolated a s before, n1.p. %Oii-207°. Alkaline h\-drolysis of the c\.clic phthalate :ifforded di1,2-dipIien!-lethanedii,l, 1n.11. i19.5-12U0 after recrystallizntion from liesnne.
Acknowledgment.---lye are indebted to Professor 11yron L. Bender for the oxygen-18 analyses and for his encouragement in this problem. CAMBRIDGE :39,~~IASSACIIUSETTS
[ C O S ? . R I U L T I O S F R U X T I E 1)EPAKT.\IEST UI: C H E A f I X R T OF THE P O L T T E C H S I C
ISSl Il'Ll'E
CIF ~ROOKLTS]
The Thermal Decomposition of Substituted !-Butyl N-Phenylperoxycarbamates' BY EUGENE L. O'BRIEN, F.I I A R S H X L L BERINGERAND KOBERTB.
IIESROBIAX4
RECEIVED J U L Y 30, 1958 ildditioii of t-butyl hydroperoxide to substituttd phenyl isocy:itiates gavc substituted t-but>.]S - p l i e r i y l p e r o s y c a r b ~ i i i i a t ~ ~ . Their ultraviolet and infrared absorption spectra and their rates of deconiposition in toluene over a 30' range of temperatures mere nieasured. First-order rate constants increased with t h e electron-releasing power of the substituents; a Hamrnctt plot with H. C . Brown's u+-values had a slope of -2.2. This ma)- explain the observation that pcroxycarbamates benring p-lriethyl or p-rnethosyl groups could not be isolated.
In a previous paper3 the first-order therinal decuiiipositions of t-butyl and cuniyl K-phenylperoxy11) P a r t of thib work wab suiiported by t h e Otlicc of S a \ al Research under Contract SIjunr-2630
