~VILLIAMJ. BAILEYAND ROBERTL. HUDSON
"SO6
t h a t 05% o f tlie thcoretical amouiit of acetic acid had hccn liberated.) Distillation of the dried organic layer through a 12-inch, helix-packed column produced 28.5 g. (9x70) of 3-methylenecycloliexene ( I ) , b.p. 108", Z z 5 D 1.4897. ilnel. Calcd. for C ~ H I OC, : 50.20; H, 10.71. Found: C, 59.46; H , 10.67. B. By Pyrolysis of 2-Methylenecyclohexyl Acetate (VII). -By t h e use of t h e apparatus described above, 57 g . (0.37 mole) of 2-methylenecyclohexyl acetate (VII) was pyrolyzed a t 500" at the rate of 0.5 g. per minute. T h e pyrolysate was washed, dried and distilled through a 12-inch, helispacked column, as described, to yield 27 g. (7870) of 3methylenecyclohesene ( I ) , b.p. 109', n 2 5 1.4891. ~ (Titration of an aliquot of t h e aqueous aashiiigs indicated t h a t 9570 of the theoretical aniount of acetic acid had been liberated.) C. By Pyrolysis of 2-Acetoxymethylcyclohexyl Acetate (VIII).-Pyrolysis of 95 g. (0.44 mole) of 2-acetoxymethJ-I-tcyclohexyl acetate (17111) was carried out a t 515' over a 3 . 5 hr. period in the apparatus described above. The pyrolysate \vas washed, dried arid distilled through a 12-inch. helix-packed column t o yield 32.5 g. (787,)of 3-methylenecyclohexene ( I ) , b.p. logo, 1.4808, and 12 g . (17%) ( i f 3-cyclohexenylniethyl acetate ( I X ) , b.p. 10O-10lo ( 2 5 nini. 1 , T Z ~ 1.4576. ~ D (Titration of a n aliquot of tlic aqueous washings indicated t h a t 87% of two molar equivalents of acetic acid had been liberated.) Anal. Calcd. for C9HL40?:C, 70.10; H , 9.15. Found: C, 70.13; H, 9.20. Ozonolysis of 3-Methvlenecvclohexene (1).--ilt the rate of 6 litersper hour, a stceam of oxygen coiitaining 0.7 milli-
[COSTRIBUTION FROM
Cyclic Dienes.
THE
1701.
78
mole of ozone per liter WAS passed for 7 hr. through a solution of 1.7 g . (0.018 mole) of 3-methplenecyclohesene ( I ) in 100 ml. of ethyl acetate cooled in a Dry Ice~-methyl Cellosolve-bath. The ethyl acetate solution was then eoncentrated t o a volume of 10 ml. b y evaporation of the solvent a t room temperature under a pressure of 40 mm. A 1-nil. aliquot of this concentrate, mixed with 0.5 g . of zinc dust, mas carefully added with stirring t o 25 ml. of 1 S hydrochloric acid. This solution was filtered and t h e filtrate was mixed with a n equal volume of a saturated aqueous solution of methone. Recrystallization of t h e resultant precipitate from cyclohexane yielded white needles of the methone derivative of formaldehyde, n1.p. 189-1917" (reported's n1.p. 191-191.5'). T h e remaining concentrate was heated on a steam-bath with 15 ml. of 30Y0 hydrogen peroxide solution until the mixture became homogeneous. -4fter the mixture had been heated for an additional hour, the excess hydrogen peroxide \vas decomposed by vigorous agitation of thc hot solution with a platinum wire for 5 h r . T h e solution was evaporated to dryness and the residue was reerystallizetl from henzciie to J-ield 1.6 g . (67%) of glutaric acid, ni.13. 95-06' (reported'!' n1.p. 97"). -4mixed melting point determination with a n authentic sample of glutaric acid sl1owi.d no depression.
-
(1s) E. C . Horning and 11, G. Horning, J . O r g . Chein., 11, 9%: (194G). (IS) R. L. Shriner a n d R. C . Fuson, "Identification of Organic Compounds," John \Tiley a n d Sons, Inc., New Y o r k , S-. Y . , 1948.
COLLEGE PARK, ~IARYLAXD
DEPARTMENT O F CHEMISTRY, L X I V E R S I T Y
OF
h'fARYLASD]
XVIII. 3,6-Dimethyl-l ,Z-dimethylenecyclohexanel
BY ~ Y I L L I A M J. BAILEYASD ROBERT L. HUDSOX? RECEIVEDXOVEMBER 14, 1955 3,6-Dimethyl-l,2-dimethyleiiecyclolie~ane was synthesized in essentially four steps from 2,4-hexadieiie in an over-all yielti of 30%. I n the final step a diacctate was pyrolyzed t o produce the diene in an 88% yield, based on unrecovered material. The structure of the diene was proved by ultraviolet arid infrared absorption spectra and conversion t o a solid derivative through a Dieis-Alder reaction.
Poly- 1,2-dimethplenecyclohexane, even C I ~ S though it is related in structure to natural rubber, possesses no rubbery properties a t room temperature but is a white crystalline solid melting a t 165'. h research program was initiated in order to determine which structural CH, l ~ . features were responsible for the striking differences in the properties of these two all-czs diene 1 s i + H+ polymers. ?he- polyditnethylenecycloliexane 92'0 . possessed a t least four structural features that cII, CI1 are not present in natural rubber, increased symmetry, added bulk, presence of a ring and ,q/cJ'20-'c /\ p 2 520 increased hindrance to rotation. In an at- , - 1 tempt to determine the effect of steric hindrance ' ) '\CH20Xc on the properties of all-cis polymers, 1,2-diCH>@.-\c methylenecycl~pentane~ and 3-methyl-l,?-di- CH, CH? methylenecy~lohexane~ were preuiouslv pre- Y \.I pared. I n brcier to prepare ai; all-cis polyiier (127; recovcry) (11' yicltl) 42%. convcrsioll 88y0 yield based 011 with a very large amount of steric hindrance, unrecovered 1- atid \.I it was of interest to prepare a substituted 1,2-dimethylenecyclohexanewith substituents in polymer froin this substituted diene indicated that both the 3- and the 6-positions. Models of the rotation would be almost completely restricted. X,(i-Dimethyl-l,~-tliinetliylcnecyclohelc~i~~e (I) ( 1 ) Previous paper i n this series, TITIS J U U R N A I . , 78, 3804 (1956) ( 2 ) O f f ~ c rof E d v a l Research Fellw,1'JT,i-l!13T, W;LS syrithesizcltl iii csscntinlly f o i i r steps iroin ?;I( 3 ) \V. J. Ilailey and I1 12. (:olden. ' l r r ~JorJRxnL., s 76, i l l s ( l ! l j t ] , h(.sa~Iic.iic.i l l :L ;;(If'; yivlti. ' t l u s ;L i i i i s t u r r (.is(4) W. J . Bailey a n d IV. I t Sorens,ni, ibid., '76, 5421 11!131).
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