GEORGE -1. CASTELLION ASD 11.. - ~ L B E R TNOYES,J R .
290
ent in our measurements, and the heat capacity data show the typical sigmoid curve anticipated in the absence of anomalous behavior. The heat capacity hump and the dielectric constant anomaly previously reported by others may be attributable to the presence of water or other impurities in their preparations. This hypothesis is consistent with the preparative methods described, but cannot be tested further because of the scant analytical data provided. Although thermal analysis14 of the NH4F-H20 system indicated simple eutectic behavior with a eutectic temperature of 24GOK. involving the phases NHIF and NH4F-Hi0, more (14) V S E'atloi and E M Polyakova J Criz C h i n U S S R , 16, 714 (1945)
[ C O N T R I B U T I O N FROM THE
recent studies by Zaromb and Brill'; have indicated that solid solutions exist in the water-rich regioii of the system. No corresponding exarninatioii of the ammonium fluoride-rich region of the phnsi. diagram has been published. Acknowledgment.-The authors acknowledge with gratitude the partial financial support of the Division of Research of the United States A1toniic Energy Commission, and cooperation in the provision of liquid helium by Dr. D. I\'. Osborne of thc Chemistry Division of .irgonne Satioiial Lxboratory. (1.5) S . Zaromb and R . Brill, .I. Cheiii. Phvs., 24, 89.5 (I!l.j(;)
.-INS ARBOR,MICHIGAS
DEPARTMENT O F CHEMISTRY,
Photochemical Studies. LII.
VCJl. 79
UNIVERSITY O F ROCHESTER]
The Nitrous Oxide-Ethane System1
BY GEORGE4. C A S T E L L I O N
AND
1%'.
A L B E R T X O Y E S , JR.
RECEIVED AUGUST27, 1956 The ratio of nitrogen formed photochemically at about 1900 A. in pure nitrous oxide t o t h a t formed under identical corn tiitions in a nitrous oxide-ethane mixture is 1.4. This indicates t h a t the primary photochemical process is probably N 2 0 = Sz 0 and that oxygen atoms react much more rapidly with ethane than with nitrous oxide. Several products are forrnctl including ethylene, butane, carbon monoxide, hydrogen, methane and probably ethanol a n d acetaldehyde. A complete elucidation of the mechanism is not possible, due to the fact t h a t oxygen atoms seem t o react more rapidly with one or more o f the products than they do with ethane itself. More ethylene is formed than one would expect from the amount of butane. I h e to secondary reactions which must involve the initially formed products i t has not been possible to obtain precise inforinntion about the reactions of oxygen atoms and of hydroxyl radicals.
+
Experimental Introduction An aluminum spark, which gives several intense lines beThe absorption spectrum of nitrous oxide probably cponsists of a continuum extending from about tween 1850 and 1990 A., was used as a source of radiation. The general design of the spark was similar t o t h a t developed 3000 A. to shorter wave lengths.? by W i g and Kistiakowsky.s Tile transformer has a capacThe photochemistry has been studied with radia- ity of 10.4 KVA4with a 17600 v . secondary when operated tion directly absorbed by nitrous oxide3 as well as on 115 v. ilctually it was operated on 220 v. primary cirthrough mercury ~ensitization.~ The reaction cuit with 0.032 mfd. capacity in parallel with the spark. .lir played directly on the spark for cooling purposes and to products (at least of the unsensitized reaction) are jets increase steadiness of operation. nitrogen, oxygen and nitric oxide. Oxygen atoms The method of focal isolation was used to obtain approsimonochromatic radiation. The change in focnl must be formed in the primary p r o c e ~ s . ~ ~ , ~ , ~ mately ,~ One of the great gaps in the interpretation of length with wave length of a quartz lens 3 cm. in diameter with a focal length of about 18 cm. was used to isolate radiaoxidation reactions of organic molecules lies in the tion of the desired wave length. T h e center of the lens was behavior of hydroxyl radicals5 The present work blocked off. A camera iris was placed between the focus was started in the hope that oxygen atoms from and the lens and t h e size of opening adjusted to allow maid\nitrous oxide would react with hydrocarbons, such light of wave length below 2000 b. t o pass. The focus was as ethane, to give hydroxyl radicals and that the located either by a piece of canary glass (Corning No. 9750) spectrobehavior of the latter could be investigated. This or by a piece of glass "silvered" with mercury. gram showed t h a t the 1850 k . line of aluniinun~did enter hope has not been realized because oxygen atoms the cell. also react rapidly with some of the reaction prodT h e portion of the glass vacuum system of the reaction ucts. Thus the over-all reaction is complex but cell and the nitrous oxide and ethane purification, storage and measuring system were kept as free from mercury as certain conclusions about it are possible. (I) This work c,f
was supported in p a r t by Contract with t h e Office N a v a l Research, United States S a r y , and with the Office of Air
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