5
875
NOTES
July, 1958
1
21
23 24 25 26 10-3 (cm.-I). Fig. 1.-Glyoxal in dioxane. 23
Y
x
27
Y I
7 6
6
22
23 24 25 26 27 .X. 10-8 (crn.-l). Fig. 4.-Glyoxal in heptane-ether, mole % ether: (1) o%, (2) 13.6010, (3) 37.6%, (4) 88.4%. 21
5
2
$4
om
4 3 2 1
21
22
23 24 25 26 27 10-3 (crn.-'). Fig. 2.-Glyoxal in heptane-dioxane, mole yo dioxane : (1) 0%, (2) 8.3%, (3) 16.2%, (4) 42.5%. Y
x
7
It has been suggested2bthat the biacetyl solvent effects might be related to an increase in the frequency of the acetyl torsional vibration.6 The mixed solvent spectra for glyoxal do not support this speculation. A thorough vibrational analysis of the glyoxal vapor spectrum has been made.' It is possible to identify these transitions with the several largest peaks in the heptane solution spectrum as indicated: I (Fig. 2), 21977-22292 cm.-l (frequency range in gas spectrum corresponding to peak I in heptane spectrum); 11, 22441-23015 cm.-'; 111, 23167-23876 cm.-l. In all of these regions much of the intensity is due t o transitions involving the torsional mode with a ground-state frequency of 127 em.-'. At 273'K. a substantial fraction of the molecules will populate the higher torsional vibrational levels. Any interaction that simply increases the vibrational separation will increase the fraction of molecules in the zero level. Transitions from the zero level are as intense as those from excited levels.6 This doesn't imply a decrease in intensity in the bands 1-111. No other vibration is involved in all three bands yet the intensity of all is reduced to about the same extent. (6) J. Sidman and D. 8. McClure, ibid., 77, 6461 (1955). (7) J. C. D. Brand, Trans. Faraday Soc., 60, 431 (1954).
6 ai5
THE CRITICAL CONSTANTS AND VAPOR PRESSURE OF CYCLOPROPANE'
3 f 4 8
BY HAROLD S. BOOTH^
AND
WILLIAMC. MORRIS^
Received February $6,1968
$3
A study of the physical constants of cyclopropane, including the vapor pressure data above one atmosphere and the critical constants, was completed in 1935, shortly after cyclopropane was introduced to the market as an anesthetic. These
2 1
21
Fig. 3.-Glyoxal
23 24 25 26 Y x 10-3 (cm.-l). in heptane-chloroform, mole form: (1) O%, (2) 55%. 22
27
70 chloro-
(1) This work was done in the Research Laboratoriea of the Western Reserve University and was supported by the Ohio Chemical & Manufacturing Co. (now the Ohio Chemical & Surgical Equipment Co.). (2) Now deceased. Formerly Department of Chemistry, Weatern Reserve University, Cleveland, Ohio. (3) Harshaw Chemical Co., Cleveland, Ohio.
876
NOTES
data are of importance in connection with the handling and administration of this agent. Cyclopropane has become extremely important as an inhalation anesthetic and since a survey of the literature reveals that similar data have not been published, it seems worthwhile to make the data obtained in this study available at this time. Experimental The critical constants and vapor pressures of cyclopropane at high pressures were investigated utilizing a very accurate type of apparatus described by Booth and Swinehart.* The procedure was t o transfer fractionally distilled cyclopropane which exhibited a constant density at constant temperature and pressure to a manifold to which Cailletet tubes were sealed. The manifold and cells were rinsed 20 times with dry air and 15 times with cyclopropane, and the tubes finally were filled to a pressure of slightly less than one atmosphere. The cells were then broken under mercury and placed in the pressure well which was connected to the pump and dead weight gauge. The assembly was placed in the thermostat and a determination was made. The critical temperature was determined by raising the temperature of the sample gradually, keeping the pressure high enough to maintain a liquid until the meniscus disappeared on stirring. The temperature was held constant a t this point for 15 to 20 minutes to attain equilibrium. The temperature was t,hen lowered and the pressure raised to liquefy the sample and the process was repeated. The highest temperature at which there were two phases visible and at which the meniscus did not reform after disappearing on stirring was taken as the critical temperature. The critical pressure was determined a t this temperature as the pressure a t which the mercury thread in the capillary did not move after standing for a long enough period to assure equilibrium.
Vol. 62 log P,,
= ___ - 1063.8
+ 7.261
This expression is in good agreement with the results of Ruehrwein and Powell6 who determined the vapor pressure of cyclopropane at pressures below one atmosphere. (5) R. A. Ruehrwein and T. Powell, ibid.. 68, 1063 (1946). ~~~
HEAT OF FUSION AND HEAT CAPACITY OF INDIUM ANTIMONIDE BY NORMAN H. NACHTRIEB AND NORIKOCLEMENT Institute for the Study of Metals, University of Chicago, Chicago, Illinoia Received February $6, 1968
The latent heat of fusion of indium antimonide is sufficiently large that it could be determined with fairly high accuracy and precision by a simple drop calorimetric method. The heat capacity was also determined for several temperature intervals in the range 20-500", although with lower accuracy. Analysis of the material for antimony gave 51.44 f 0.16%, as compared with the theoretical value of 51.48%. Semi-quantitative spectrographic analysis revealed Fe (0.001%), Pb (0.001%), Sn (O.OOl%), Mg (0.001%), Si (0.0001%) and Cu (0.0001%). A weighed quantity of InSb, sealed in an evacuated Vycor bulb of known weight, was heated in a tube furnace; the temperature was controlled by a Leeds and Northrup Micromax with four chromel-alumel thermocouples in series to permit regulaResults.-The critical temperature and critical tion to h0.5". For the latent heat of fusion, drops were made from temperatures just above and just pressure of cyclopropane are given in Table I. below the melting point (525").' (The melting point of the material was verified to lie within 1' TABLE I Critical Critical of its reported value by trial inspections on withSample temp., pressure drawing it quickly from the furnace at temperaOC. atm. No. tures close to 525O.) The calorimeter was a 11 124.65 54.22 liter glass Dewar vessel equipped with a stirrer, 2 124.66 54.24 Beckman thermometer, and a brass tube for guid3 124.65 54.22 ing the specimen from the furnace. A copper Av. 124.65 54.23 gauze liner in the calorimeter gave protection The vapor pressure of cyclopropane as a func- against breakage even though the specimen fall tion of temperature was determined during the was almost free. About 825 g. of water was used critical constant experiments on the same samples in the calorimeter, and weight losses by evaporation of cyclopropane. The results of these determina- did not exceed 0.2 g. The water equivalent was determined by mixing weighed quantities of water tions are given in Table 11. of different temperature, and found to be 86.8 g. Two series of runs were made, with 0.2104 and TABLE I1 0.1620 mole of InSb. The average of six determiVAPORPRESSURE OF CYCLOPROPANE nations was 11.2 h 0.4 kcal.mole-' and the enSample Temp., Pressure, Sample Temp., Pressure, no. OC. atm. atm. no. OC. tropy of fusion is accordingly 14.1 cal.mole-'deg.-'. C 115.34 16.66 45.26 C 61.32 Measurements of the heat capacity were made in 15.25 B 40.98 110.02 B 52.42 a similar manner for the temperature intervals 12.15 105.30 39.20 A C 43.28 20-go", 90-170', 170-350" and 350-500'. CorB 9.60 34.14 101.31 B 36.25 rections for the heat capacity of Vycor were made 7.82 A 91.10 A 32.42 30.13 from runs with an evacuated bulb filled with 5.30 88.29 B 27.18 B 16.78 crushed Vycor. The measurements are of lower 4.01 81.19 25.79 A A 11.02 accuracy than the heat of fusion because the heat 3.62 76.38 C 23.48 B 7.56 content of the Vycor was about equal to the heat 71.42 B 2.38 22.32 A 3.00 content of the InSb. For the four temperature 64.92 A 18.08 intervals above the heat capacity of InSb was When the data in Table I1 are plotted as a func- found to be 0.052, 0.056, 0.062 and 0.062 ca1.g.-'deg. -l, respectively. tion of temperature they yield the expression Acknowledgments.-The work described was in (4) H. 6. Booth and C. F. Swinehart, J . A m . Cham. Sac., 67, 1337 (1935).
(1) T. S. Liu and E. A. Peretti, Trans. J . Metals, 3, 791 (1951).
