NOTES
826
and measuring the evolved gas at 140" a value of k of 0.00025 see. - l was obtained, a result which agrees with that reported by J. Laskin.la Therefore, at this temperature, malonic acid decomposes about five times as fast in glycerol, and 37 times as fast in dimethyl sulfoxide, as it does alone.
BOILING POINT-COMPOSITION DIAGRAM FOR THE SYSTEM 1,4-DIOXANE-n-BUTYL ALCOHOL BY JAMESB. MCCORMACK, JOHNH . WALKUPAND
Vol. 60
carried out in an Othmer equilibrium stilL2 The pressure was maintained a t 760 mm. of mercury by means of a Cartesian m a n ~ s t a t . ~ Equilibrium was assumed to be attained when samples checked on the refractometer had a constant reading, and the composition of the samples was determined from a refractive index-composition curve. The boiling point was read with an accuracy of 10.05O. The data secured are given in Table I and also presented graphically. ( 2 ) D. F. Othmer, Anal. Chem., 80, 763 (1948). R. Gilmont, Ind. Eng. Chem., Anal. Ed., 18, 633 (144R).
(3)
R. I. RUSH
Chemistry Laboratory, Centre College of Kentucky, D a n d l e . K y . Received January 23, 1966
I n order to extena information previously obtained in this Laboratory' the boiling point-composition diagram for the system 1,4-dioxane-n-
RADIOLYSIS OF ETHANE: MOLECULAR DETACHMENT OF HYDROGEN BY LEONM. DORFMAN Qeneral EEectric Research Laboratory Schenectady, New York Received January S4# 1966
118
The chief products in the radiolysis of ethane are hydrogen and a polymeric liquid,lp2 the yield for hydrogen formation being approximately 3.9 molecules/lOO e . ~ . This ~ , ~note reports the results of experiments which show that a large fraction of the 112 hydrogen is formed intramolecularly by direct de9 tachment of molecular hydrogen without the apparent intermediate formation of single atoms of a hydrogen. ri Molecular detachment of hydrogen is inherent 106 in one of the seven primary processes suggested by Williams and E s s ~ xnamely, ,~ direct formation of hydrogen and ethylene ion, based on the observed5 mass spectral pattern of ethane. The hydrogen may be released from an excited ethane molecule or ion. It may originate from more com100 I I I I I 0 20 40 60 80 100 plex ions which can be formed in ion-molecule reactions which occur with high efficiency as shown n-Butyl alcoli,l, T . Fig. I -Boiling point-cwnposition diagram for the system recently by Steverison and Schissler.6 1,Pdiosane-n-butyl alcohol. The data which follow provide no information concerning the nature of the transitory entity butyl alcohol has been determined. The dioxane from which the hydrogen is released. They indiand n-butyl alcohol were purified by methods de- cate only the fraction of the total hydrogen formed scribed elsewhere, ' and the determinations were by molecular detachment. In these experiments a number of mixtures of TABLE I BOILINGPOINT-COMPOSITION DATA FOR THE n-BuTYL deuteroethane and normal ethane have been irALCOHOL-1,4-DIOXANE SYSTEM AT ONE ATMOSPHERE radiated in a 1 MeV. electron beam and the hydrogen isotope fraction analyzed mass spectrometriPRESSURE cally. The degree of isotopic randomization of the Composition Composition !.p.. (wt. % alcohol) B.p (wt. Sr, alcohol) hydrogen is a measure of the relative occurrence C. Vapor Liquid Vi' Vapor Liquid of single-atom reactions and molecular detachment 101.1 0.0 0.0 109.3 48.9 ti5.4 if it is known that secondary exchange produces no 101.5 3.0 4.5 110.55 55.4 73.2 appreciable isotopic mixing. 101.8 4.9 6.7 110.8 57.8 74.2 Experimental 102.2 7 . 5 10.7 111.25 59.8 75.8 105.0 106.25 106.5 106.95 107.35 107.4 107.55 108.5 108.8
22.2 31.9 31.6 33.8 38.0 38.8 37.2 43.8 45.6
36.8 47.5 46.1 52.1 54.4 54.4 53.6 60.8 62.2
111.65 112.3 112.65 113.8 115.1 116.0 116.5 117.5
62.3 67.0 67.0 75.8 85.0 90.6 94.2 100.0
76.3 80.1 81.1 85.9 91.2 94.2 96.4 100.0
(1) R. I. Rush, D. C. Ames, R. W. Horst and J. R. McKay, THIS JOUBNAL,
in press (18513).
The deuteroethane was obtained from Tracerlati, Inr. It contained 98 f 1 isotopic per cent. deuterium as determined mass spectrometrically . The deuteroethane was degassed at - 195", then fractionated twice by bulb-to-bull) (1) W. M u n d a n d W. Koch, BdE. 8 0 0 . chim. Belg., S4, 119 (1925). ( 2 ) S. Lind and Bardwell, J . A m . Chem. Soc.. 48, 2335 (142G).
C.
D. C.
(3) L. M. Dorfinan, F. J. Shipko and C. F. Pachucki, to be publiahed. (4) N. T. Williams and H. Esaex, J . Chem. Phgs., 17, 995 (1949). ( 5 ) J. A. Hipple, Jr., Phys. Rev., S3, 530 (1938). ( G ) D. P. Stevenson and D. 0. Schissler. J . Chem. Phys.. 2 3 , 1353 (1955).
c
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