4304
~ 7 ~ 73 1 .
NOTES
suspensions were dissimilar only in the region from 8 to 12 microns, possibly due to the differences in crystal structure. Biological assays of the two forms showed no significant difference in estrogenic activity.3
bromide in the presence of oxygen was irradiated for 0.5-1 hour the tube was filled with brown vapors, which became more deeply colored as the time of irradiation increased. The mechanism by which the oxidation of aluminum bromide proceeds was not studied. It is very likely that the promoting ( 3 ) Modified Kahnt-Doisy method, by S. Margohn and M T. effect of the oxygen is due to the oxidation of Spoerlein, Biological Laboratories of this Company aluminum bromide with formation of bromine. QUALITYCONTROL DEPARTMEXT SCIIERINC CORPORATION The latter then reacts with methylcyclopentane BLOOMFIELD, N. J. RECEIVED MAY9, 1950 to form bromomethylcyclopentaane, which is a chain initiator for the isomerizati~n.~The oxidation of aluminum bromide in solution in hydroIsomerization of Saturated Hydrocarbons. carbons seems to proceed even in diffused light. VII1.I The Effect of Oxygen and The inhibiting effect of benzene upon the isomthe Isomerization of Methylcyclopen erization of methylcyclopentane is not entirely Presence of Aluminum Bromide unexpected; it is most likely due to the removal of BY HERMAN PINES,EUGENE ARISTOFF~ AND V. N. IPATIERF the chain initiator through the reaction with benzene, as has been shown previously.'~5 The promoting effect of oxygen upon the isomTABLE I erization of n-butane and n-pentane in the ISOMERIZATION OF METHYLCYCLOPENTANE presence of either aluminum chloride or aluminum Methylbromide has been reported previously.5 This cycloReactant charged Cyclopentane moles per 100 moles hexane study has now been extended to determine Irradi- Reac- used, of methylcyclopentane prowhether oxygen in the presence of aluminum ation, tion moles duced, Expt hours tube6 X 102 AlBrr Oz CSHs yo bromide but in .the absence of added hydrogen 1 18" P 2 22 2 01 0.18 0 0 bromide promotes the isomerization of saturated 2 18" P 3 10 4 00 1.05 0 15 cyclic hydrocarbons such as methylcyclopentane 3 18 P 2 11 2 . 0 2 0 18 0 6 to cyclohexane. The experiments were con4 IS Q 1.37 199 17 0 13 ducted in either quartz or Pyrex reaction tubes. 5 18 Q 1.04 4 02 .96 0 42 It was noticed that in diffused light, and a 6 I8 Q 2.60 2 04 .20 0.037 0 Pyrex reaction tube, with methylcyclopentane, 7 18 Q 1 00 3.98 .96 0.039 6 aluminum bromide and oxygen in a molal ratio a In experiments 1 and 2 the reaction tubes were not of 100:2 :0.2, isomerization of methylcyclopentane I, P, Pyrex reaction tube; Q, quartz reaction to cyclohexane does not occur. When the re- irradiated. tubc . action tube was exposed for eighteen hours to a Experimental quartz cadmium-mercury arc lamp 6y0 of the The high vacuum apparatus and procedure have been methylcyclopentane was isomerized; the extent of described previously.1,6 Linde oxygen was introduced into isomerization was increased to 13% when a quartz the apparatus through a phosphorus pentoxide drying tube. After being measured in the calibrated portion of reaction tube instead of a Pyrex one was used. the Topler pump, the oxygen was transferred to an amThe introduction of a larger amount of oxygen poule having a thin walled break-off. The sealed aminto a Pyrex reaction zone, namely, 1 mole equiv- poule was carefully placed in the reaction tube, then the alent of oxygen per 100 moles of methylcyclo- latter evacuated. After the other reactants had been the reaction tube was sealed off then shaken, in pentane and 4 moles of aluminum bromide, caused added, order to break the thin bulb of the ampoule containing the isomerization of 15% of methylcyclopentane; oxygen. The composition of the hydrocarbons obtained when a quartz reaction tube was used and irradi- from the reaction was determined by means of infrared absorption spectra. ated, 42% of cyclohexane was formed. In line with previous 0bservations1*~~5 it was (6) H. Pines, B. M Abraham and V. N. Ipatieff, ibid., 70, 1742 noticed that the presence of about 0.04 mole per (1948). cent. of benzene in methykyclapentane greatly THEIPATIEPFHXG3 PRESSUREAND LABORATORY reduces the degree of isomerization. The experi- CATALYTIC DEPARTMENT OF CHEMISTRY mental results are summarized in Table I. UNIVERSITY During the course of this study it was observed NORTHWESTERN EVANSTON, ILLINOIS RECEIVED MARCH 22, 1950 that aluminum bromide per se placed in a quartz tube and irradiated did not change coloration. It was noticed however that when aluminum The Structure of Methyl Acetylacrylate] (1) For paper V I 1 of this series see H. Pines, E. Aristoffand V. N. Ipatieff. THIS JOURNAL, 78,4055 (1950). (2) Universal Oil Products Company Predoctoral Research Fellow 1947-1949. (3) H Pines and R. C. Wackher, Tzus JOURNAL, 66,599 (1946). (4) J. M . Mavrty, H. Pines, R. C. Wackher and J. A. Brooks, I d . En;. Chcm., 10, 2374 (1948). (5) E. Pines, E. Ariatoff m d V. ET. Xpaficff, T a a JOWRNAL, T I , 749 (19491.
BY SAMUEL RAYMOND
Methyl acetylacrylate was first prepared in 1914 by Pauly, Gilmour and Willla by the dehydro(1) This work waa supported by a grant from the National Institutes of Hedth and from the John and Mary R. Mar!& Poundation. 1.1( Pfial~,Wmour nnd Will, Ann., 408,1x9 (1814).
