2252
WILLIAM D. HUNTShlAN
Compound D was identified as gallic acid chromatographically and spectrally. Paper chromatograms of D showed a weak ellagic acid spot and an intense spot whose Rr values were identical with those of gallic acid (Rr 0.50 in lOy0 aqueous acetic acid; Rr 0.74 in 1-butanol-acetic acid-water. Two-dimensional co-chromatograms of D and authentic gallic acid in these solvents showed only one major spot. The spectrum of the intense spot in a two-dimensional chromatogram of X was determined directly on the paper strip.'O It had Am, 279 mp. After dipping it into alcoholic sodium acetate and drying i t had Amax 264 nip. Gallic acid, simi278 and 263 mp, respeclarly chromatographed, had A,, tively. Alkaline Hydrolysis of Juglank--Aqueous sodium hydroxide (50.0 ml., 10%) was added to a solution of juglanin (5.0 g.) in water (50.0 ml.) under au atmosphere of nitrogen. The stoppered reaction flask was allowed to stand at room ( I O ) A. E. Bradfield a n d A . E Flood, J . C h c m . Soc., 4740 (1952).
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temperature for 5 days during which time a yellow sodium salt crystallized. The sodium salt was collected, suspended in warm water and treated with excess of hydrochloric acid. Ellagic acid,m.p. >360",was thereby obtained(l.;g., 347,). .After removal of the sodium ellagate, the sodium hydroxide filtrate was acidified with dilute sulfuric acid. -1dark tar was precipitated. The aqueous acid solution was decanted from the tar and extracted with ether for 6 hours in a colitinuous liquid-liquid extractor. The ether extract was dried ( SalS04) and evaporated. X slightly brown, crystalline solid, identified chromatographically and spectrally as gallic acid, was obtained (0.645 g., 12.97;). RecrJ-stal. lized from water the product had m.p. 258-259", uiidepressed on admixture with gallic acid.
Acknowledgments.-The author is indebted t o L. 11.White for the elementary analyses. PASADESA,
CALIF.
DEPARTMEXT OF CHEMISTRY, OHIO UNIVERSITY]
Reactions of Diolefins at High Temperatures. I. Kinetics of the Cyclization of 3,7-Dimethyl-l,6-octadiene BY WILLIAM D. HUNTSMAN A N D THOMAS H. CURRY RECEIVED SOVEMBER 14, 1957 The cyclization of 3,7-dimethyl-1,6-octadiene a t 382 5' and 409" is first-order, and the rate is not affected by the presence of nitric oxide or ethylene oxide. The Arrhenius energy of activation is 35.2 kcal./niole and the entropy of activation is -18 e.u. An intramolecular mechanism is proposed.
Pinane (I) isomerizes a t 450-500' to give a mix(11) and 1,2ture of 3,7-dimethyl-l,B-octadiene dimethyl-3-isopropenylcyclopentane(111).2 . 3 Furthermore, it has been shown that I11 arises by
mixture if a radical chain mechanisni were opera. tive.5 It was felt that the cyclization of 1,6-diolefins warranted further study, with the particular goal of substantiating or ruling out a free radical chain mechanism. Xccordingly, an investigation of the kinetics of cyclization of 3,'T-dimethyl-1,6-octadiene was undertaken. Several preliminary experiments were coiiductcd to gain an estimate of the effect of free radical chain I I1 111 initiators. The results of some of these expericyclization of 11. Under siinilar conditions, 6,6- ments are summarized in Table I. t-Butyl peroxide dimethylnorpiiiane (IT.') isomerizes to l-methyl-2- and ethylene oxide have been widely used as initiaisopropenylcyclopentane (17) , presumably ~ ~ 7i a tors for reactions which occur by radical chain methyl- 1,G-octadiene (VI). mechanisms. They are observed to accelerate reactions, and to induce reactions a t temperatures where the reactants are normally stable. For example, t-butyl peroxide sensitizes the polymerization of olefins, and the decarbonylation of aldehydes6; ethylene oxide has been used as an initiator for the decomposition of alkanes, ethers and IV v VI aldehydes.' It was suggested that the cyclization step in Inspection of Table I reveals that these initiators these reactions proceeds by a free radical chain exerted little if any effect on the cyclization of 11, mechanism. Several points, however, argue the major effect being to increase the extent of polyagainst such a mechanism. Among them may be merization. The small amount of cyclization obmentioned the virtual absence of polymeric prod- served in run 1 probably does not signify that the ucts. Also the reactions are surprisingly specific peroxide sensitized the cyclization reaction. Mixas compared with most hydrocarbon-pyrolysis re- tures of I1 and I11 were used in these experiments actions. One would expect a much more complex (1) This research was supported by t h e United S t a t e s Air Force, through t h e Ofice of Scientific Research of t h e Air Research a n d Development command. (2) V. S . Ipatieff, \V. 11. H u n t s m a n and 1%.Pines, THISJ O I . R N A I . , 76, 6222 (1953). (3) H. Pines, S. E. H o f f m a n a n d V. S . Ipatieff, ibid.. 76, 4412 (1954). ( 4 ) €I. Pines and S. Ii Huffman. z b > d . , 76, ,4417 i l ( l i 1 ) .
( 5 ) J . E. LeRIer, "The Reactive Interniediates of Organic Chemii193ti, 11 242. try." Interscience I'ubliihers, Inc.. h-cw I'ork, S .I-., ( L j ) F.F. R u s t , F. H. Seubold and IV. IS. Vaughan, THISJ O U R N A L 70, 9,5, 4253 ( 1 9 l 8 ) ; E. H. Farmer and C. C:. Moore, J . Chpni. S o c . , 1 3 1 (1951): I t . S.Ha?!-l-arda n d I\Simpson, '. T r ~ i i s F. a i u 212 (1951). (71 C. J. 11. Fletcher, T H I S J O U R N A L , 58, 534 (193ti); C . J . h l . Fletcher and G. K. Rollefson, i b i d , 58, 213; , l Y 3 l j ) , L. S. Echols and I
