NOTES
430
Acknowledgment. The authors acknowledge Professor P. Goldfinger's interest in this work. They thank the Union Mini&-e du Haut Katanga for the germanium used in this investigation.
Table I : "Heat Capacity of AZBN. T
CP A H Run A Series I
Heat Capacities and Thermodynamic Properties of Globular Molecules. XI.
Melting of
3-Azabicyclo[3.2.2]nonane
459,54 464.94 466.33 469.53
[Units: cal., mole,
T
CP
T
CP
467.57
148.3
430.63 438.92 447.07 455.06
63.42 64.22 66.44 67.64
Series I11
74.5 290 1442 113.2
By Claus A. Wulff and Edgar F. Westrum, Jr.'
AH Run
B
Department of Chemistry, Unizersity of Michigan, Ann Arbor, Michigan (Eeceited September 3. 1963)
A H Run
C
OK.]
470.86 475.41 479.88 484.59 489.43
72.18 72.95 73.17 74.13 74.53
Series V 329.79 338.85 347.88 356.87 365.80 374.31
AH Run D
56.53' 56.59 56.77 57.09 57.60 58.17
AH Run E
Series I1
Fusion Runs G
A previous paper in this series2 presented the lowtemperature heat capacity of 3-azabicyclo 13.2.21nonane (AZBK) and revealed a solid-solid transition at 297.78"K. with an entropy increment of 11.68 cal./ (mole OK.). The transition was ascribed to a rotational reorientation process leading to a plastically crystalline phase (crystal I), Further evidence for the plastically crystalline nature of this phase has been obtained by determination of the thermodynamics of melting and the heat capacities of crystal I and the liquid. The thermal properties of AZBX were determined between 280 and 490OK. by adiabatic calorimetry using the previously described3 hIark IV intermediate range thermostat, a silver calorimeter (laboratory designation W-22)' and a capsule-type platinum-resistance thermometer (laboratory designation A-7). Also described elsewhere are the quasi-adiabatic calorimetric method4 and the computer program for the conversion of data to thermodynamic functions.6 The measurements were made on a single loading of 55.1265 g. (in vacuo) of an AZBPU' sample previously.characterizedI2 which contained 0.21 mole % impurity as determined by fractional melting. The heat capacity of the sample exceeded 75% of the total measured over the entire range. All calculations are based upon a calorie defined as 4.1840 j., an ice point temperature of 273.15OK., and a gram formula mass of 125.216 g. The heat capacity data presented in Table I have been adjusted for curvature and for vaporization into the free volume of the calorimeter on the basis of a preliminary survey of the sublimation pressuree6 The data agree to O.lyc with the low-temperature results over the common range between 285 and 350°K. Comparison of enthalpy-type runs with the integration of the heat capacity data given in Table I1 indicates good accord. Five determinations of the enthalpy The Journal of Physical Chemistry.
459.61 462.37 464.47 465.56 466.08 466.35 466.50
A H Run F
71.8 96.5 205 487 924 1822 2309
Series VI Series IV
406.17 413.75 422.25
~
~~~~~~~~
~
Table 11: Enthalpy Runs for AZBN. Run
Ti
A
284,43
B
319.12 432.38 400.58
C D
383.60 392.77 401.84 410.80
60.86 61.59 62.52
58.86 59.64 60.45 61.27
~~
[LTnits: cal., mole, OK.]
Tz
AH
325.60 403.30 458.21 447.27
6647 4868 1693 2933
SC,dT
5650 4865 1693 2930
of melting, including two fractional melting series, are summarized in Table 111. The sample melted under its own vapor pressure at 466.55OK. Assuming the T o whom correspondence concerning this work should be addressed. C. M . Barber and E F. Westrum, Jr., J . Phye. Chem., 67, 2373 (1963). E. F. Westrum, Jr., and J. C. Trowbridge, Ret. Sci. Instr., in press. E. F. Westrum, J r . , J. B. Hatcher, and D. W. Oshorne, J . Chena. Phys., 21, 419 (1953). B. H . Justice, A4ppendix to Ph.D. dissertation, University of Michigan; c f . U. 9. Atomic Energy Commission Report T I D . 12722, 1961. Three series of static sublimation pressure measurement8 made by James R. Trudell as an undergraduate research problem accord with the equation, log P(cm.) = 7.907 - 2 7 2 7 / T , within 1% over the range 303 to 443'K. and were used as the basis for the vaporization corrections. These values indicate a triple point pressure of 1.28 atm. which accords with the reported sublimation of this substance prior to melting (cf. Technical Data Report No. X-119, Eastman Chemical Products, Inc., Kingsport, Tennessee, May, 1962).
NOTES
43 1
impurities to be liquid-soluble solid-insoluble, the triplie point of the pure substance is 467.12 f 0.01OK. The five determinations of the enthalpy of melting yield a mean value of 1653 f 2 cal./mole and 3.549 cal./ (mole OK.) for the enthalpy and entropy of melting.
Acknowledgment. The authors gratefully acknowledge the partial financial support of the Division of Research of the United States Atomic Energy Commission and C. A. W. acknowledges the support of the Institute of Science and Technology of the University of Michigan in the form of a postdoctoral fellowship.
Table 111: Melting Data for AZBN.
(7)
[Units: cal., mole, "K ]
Designation
TI
Ta
Serien I Series I1 Fusion Run E Fusion Run F Fusion Run G
455.31 458.21 455.61 457.05 454.75
472.53 473.14 479,72 474.30 476.46 Av.
Hi75
=
AHm =
Cf. J. Timmermans, J . Phys. Chem. Solids, 18, 1 (1961).
- H46sa
3040.4 3037.1 3039,l 3036.6 3038.5 3038.3 f 1 . 5 1653 f 2
Corrected for enthalpy increments between T I and 455"K., Tz and 475"K., and for quasi-adiabatic drifts. a
The Synthesis and Infrared and Nuclear Magnetic Resonance Spectra of Ammonium Dicyanamide
by JameB W. Sprague, Jeanette G. Grasselli, and William M. Ritchey T h e Standard Oil Company (Ohio),Research Department, Cleveland. Ohio (Received October 2, 1963)
Since the value of ASm is below the (arbitrary) limit of 5 cal./(mole "K.) prescribed by Timmermans' for the definition of a plastic crystal phase, AZBK meets all the macroscopically observable criteria for plastic crystallinity, i e . , solid-solid transition, low entropy of fusion, high melting temperature, and high vapor pressure. The substance is one of a number of compounds related to bicyclooctane that are being investigated in this laboratory. Discussion of the molecular disordering process leading to the plastic crystal phases mill be deferred until more experimentall evidence becomes available. A brief summary of the thermodynamic properties, is made in Table I V ; those for the gaseous phase also involve the sublimation pressure data.6
The metallic salts of dicyanamide have been known in well characterized forms for many years.' Their infrared spectra, have recently been described. hletallic salts are prepared by methods such as the alkali fusion of cyanamide with melon (or other highl-y condensed members of this carbon-nitrogen system) or the reaction of disodium cyanamide with cyanogeii halide followed by metathetical exchange with an appropriate salt. These reactions were not appropriate to the ammonium salt although a crude sample had been prepared.'^^ We have found that the salt may be obtained by the addition of concentrated solutions of cyanogen bromide to liquid ammonia. Over a period of 1.5 hr. 150 ml. of a glyme (1,2dimethoxyethane) solution containing 100 g. of cyano gen bromide was added to 250 ml. of liquid ammonirt with vigorous stirring. The ammonia evaporated slowly from the reaction mixture which then stood over a weekend. Two phases separated. The super.natant solution was decanted from the solids and dis-. carded. The solids which consisted primarily of ammonium bromide and ammonium dicyanamide were extracted with a mixture of 200 nil. of e;chyl acetate and 200 ml. of acetone which was evaporated to about ~
Table IV : Thermodynamic Properties of AZBN. cal., mole, "K.] T
CP
S"
H o - Roo
[Units:
-(Uo
-
Hoo)/T
Crystal I 65.61 12992 28.49 73.40 15809 33.63 80.79 19052 38.46 ... 83.30 20201 40.05 Liquid 467.12 ... 86.84 21854 40.05 500 (75.92)" (91.86) (24281) (43.30) Vapor ... 101,0' 28290' 30.3' 400 a Values in parentheses are extrapolated from ca. 495°K. * Not corrected for deviation from ideality; L e . , S,,,,, -. Sary.tal 1 = R In P f A H s / T = R In 0.1629 atm. 12480/400. 350 400 450 467.12
56.83 60.28 65.84
+
(1) W. Madelung and E. Kern, Ann., 427, 1 (1922). ( 2 ) M. Kuhn and R.Mecke, Chem. Ber., 3010 (1961). (3) The synthesis of the ammonium salt and its infrared spectrum a8 a KBr pellet have been presented recently by M. B. Frankel, et al., J . Org. Chem., 28, 2428 (1963). The bands listed by these authors in the C=N saretching frequency region differ slightly from ours, but it is not possible to determine if.partial cation exchange has occurred in their pellet without data in the 900950 cm. -1 region.
Volume 68, Number 2
February, 1964
