Low-temperature heat capacity and thermodynamic properties of endo-Tricyclo[5.2.1.02,6]decane

Article abstract of DOI:10.1016/j.jct.2003.08.013

Endo-Tricyclo[5.2.1.0^2,6]decane (CAS 6004-38-2) is an important intermediate compound for synthesizing diamantane. The lack of data on the thermodynamic properties of the compound limits its development and application. In this study, endo-Tricyclo[5.2.1.0^2,6]decane was synthesized and the low temperature heat capacities were measured with a high-precision adiabatic calorimeter in the temperature range from (80 to 360) K. Two phase transitions were observed: the solid-solid phase transition in the temperature range from (198.79 to 210.27) K, with peak temperature 204.33 K; the solid-liquid phase transition in the temperature range from 333.76 K to 350.97 K, with peak temperature 345.28 K. The molar enthalpy increments, ΔH _m, and entropy increments, ΔS_m, of these phase transitions are ΔH_m, = 2.57 kJ · mol^-1 and ΔS_m = 12.57 J · K^-1 · mol ^-1 for the solid-solid phase transition at 204.33 K, and, Δ_fusH_m = 3.07 kJ · mol^-1 and Δ_fusS_m = 8.89 J · K^-1 · mol^-1 for the solid-liquid phase transition at 345.28 K. The thermal stability of the compound was investigated by thermogravimetric analysis. TG result shows that endo-Tricyclo[5.2.1.0^2,6]decane starts to sublime at 300 K and completely changes into vapor when the temperature reaches 423 K, reaching the maximal rate of weight loss at 408 K.

Full text of DOI:10.1016/j.jct.2003.08.013

J. Chem. Thermodynamics 35 (2003) 1897–1904
www.elsevier.com/locate/jct
Low-temperature heat capacity
and thermodynamic properties
2
;6
of endo-Tricyclo[5.2.1.0 ]decane
a,b
a,
Li-Guo Kong , Zhi-Cheng Tan , Jie Xu ,
c
*
a
Shuang-He Meng , Xin-He Bao
b
a
Thermochemistry Laboratory, Dalian Institute of Chemical Physics,
Chinese Academy of Sciences, Dalian 116023, China
b
State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics,
Chinese Academy of Sciences, Dalian 116023, China
c
Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
Received 27 March 2003; accepted 20 August 2003
Abstract
2
;6
Endo-Tricyclo[5.2.1.0 ]decane (CAS 6004-38-2) is an important intermediate compound
for synthesizing diamantane. The lack of data on the thermodynamic properties of the com-
2;6
pound limits its development and application. In this study, endo-Tricyclo[5.2.1.0 ]decane
was synthesized and the low temperature heat capacities were measured with a high-precision
adiabatic calorimeter in the temperature range from (80 to 360) K. Two phase transitions were
observed: the solid–solid phase transition in the temperature range from (198.79 to 210.27) K,
with peak temperature 204.33 K; the solid–liquid phase transition in the temperature range
from 333.76 K to 350.97 K, with peak temperature 345.28 K. The molar enthalpy increments,
ꢁ
1
DH
DS
m
, and entropy increments, DS
m
, of these phase transitions are DH
m
¼ 2:57 kJ ꢀ mol and
ꢁ1
ꢁ1
m
¼ 12:57 J ꢀ K ꢀ mol
¼ 3.07 kJ ꢀ mol and Dfus
at 345.28 K. The thermal stability of the compound was investigated by thermogravimetric
for the solid–solid phase transition at 204.33 K, and,
ꢁ1
ꢁ1
ꢁ1
D
fus
H
m
S
m
¼ 8.89 J ꢀ K ꢀ mol for the solid–liquid phase transition
2;6
analysis. TG result shows that endo-Tricyclo[5.2.1.0 ]decane starts to sublime at 300 K
and completely changes into vapor when the temperature reaches 423 K, reaching the maximal
rate of weight loss at 408 K.
Ó 2003 Elsevier Ltd. All rights reserved.
*
Corresponding author. Tel.: +86-411-4379215; fax: +86-411-4691570.
E-mail address: tzc@dicp.ac.cn (Z.-C. Tan).
0
021-9614/$ - see front matter Ó 2003 Elsevier Ltd. All rights reserved.
doi:10.1016/j.jct.2003.08.013

1898
L.-G. Kong et al. / J. Chem. Thermodynamics 35 (2003) 1897–1904
Keywords: Endo-Tricyclo[5.2.1.02;6]decane; Heat capacity; Phase transition; Adiabatic calorimetry;
Thermodynamic property
1
. Introduction
Diamantane has been widely used in medicine, dye and pesticide industries. An
important route to synthesize the compound is the isomerization of endo-Tricy-
2;6
clo[5.2.1.0 ]decane (molecular formula: C H , CAS 6004-38-2), which is produced
16
10
through hydrogenation of dicyclopentadiene, the main component of C distillates
5
2;6
of oil plants [1]. Endo-Tricyclo[5.2.1.0 ]decane, as one important intermediate com-
pound of synthesizing diamantine, has been studied recently. But the thermody-
namic properties of the compound has not been reported sufficiently. In order to
increase understanding of the properties of the compound, we measured some ther-
modynamic properties of this compound.
In the present study, the low-temperature heat capacities of the compound have
been measured in the temperature range from (80 to 360) K. Two phase transitions
were observed. The enthalpy and entropy increments of the two phase transitions
have been determined. In addition, the thermal behavior of sublimation and evapo-
ration was further investigated through thermogravimetric analysis.
2
. Experimental
2
.1. Sample preparation and purity analysis
5
C distillates of oil plants were separated to obtain dicyclopentadiene. Then dicy-
clopentadiene reacted with hydrogen in an autoclave for 10 h at the temperature 393
K with the pressure 1.0 MPa using Raney Ni as the catalyst. Then the mixture was
filtered to get liquid mixture. Then the liquid mixture was fractionated to produce
2;6
endo-Tricyclo[5.2.1.0 ]decane with high purity. The process is
ð1Þ
The sample was dissolved in ethanol and analyzed to test the purity and the anal-
ysis was conducted on an Agilent 4890D gas chromatograph with FID. No impurity
was found in the sample in the present experiment.
2
.2. Adiabatic calorimetry
Heat capacity measurements were carried out in a high-precision automatic adi-
abatic calorimeter described in detail previously [2]. The sample amount used for

L.-G. Kong et al. / J. Chem. Thermodynamics 35 (2003) 1897–1904
1899
the heat capacity measurement is 2.5168 g, equivalent to 15.840 mmol, based on a
ꢁ
1
molar mass of 136.236 g ꢀ mol .
Prior to the heat capacity measurements on the sample, the reliability of the ca-
lorimetric apparatus was verified by heat capacity measurements of the reference
2 3
standard material a-Al O . The deviations of our calibration results from the recom-
mended values reported by Ditmars et al. [3] of the former National Bureau of Stan-
dards are within of ꢂ0.2% in the temperature range from (80 to 400) K.
2
.3. TG analysis
Thermogravimetric analysis of the sample was carried out by a TG analyzer
Model: TA2950, Du Pont, USA) under high purity nitrogen (99.999%) with the flow
(
ꢁ
1
rate of 60 ml ꢀ min . The mass of the sample used for TG analysis was 7.8 mg. The
heating rate was 0.17 K ꢀ s .
ꢁ
1
3
. Results and discussion
3
.1. Heat capacity
2;6
The experimental molar heat capacities of endo-Tricyclo[5.2.1.0 ]decane are
shown in figure 1. and tabulated in table 1. The molar heat capacities were fitted to
the following polynomials in reduced temperature (X), by means of least square fitting.
In the temperature range of (78 to 198) K
700
600
500
400
300
C10H16
p
C
200
100
0
100
150
200
250
300
350
2;6
FIGURE 1. Experimental molar heat capacities Cp;m of endo-Tricyclo[5.2.1.0 ]decane as a function of
temperature T.

1900
L.-G. Kong et al. / J. Chem. Thermodynamics 35 (2003) 1897–1904
TABLE 1
The experimental molar heat capacity of endo-Tricyclo[5.2.1.0 ]decane molar mass M ¼ 136.236 g ꢀ molꢁ1
2;6
T/K
Cp;m
T/K
Cp;m
T/K
Cp;m
J ꢀ Kꢁ ꢀ molꢁ1
1
J ꢀ Kꢁ1 ꢀ molꢁ1
J ꢀ Kꢁ1 ꢀ molꢁ1
7
8
8
8
9
9
9
9
8.33
53.694
53.857
54.589
55.981
56.482
57.809
58.990
60.069
61.205
62.140
63.074
64.894
66.520
67.849
68.794
70.560
72.724
73.586
75.835
76.980
78.634
79.978
81.225
82.561
84.803
85.456
87.306
88.357
90.513
91.386
93.266
95.158
97.358
99.964
102.01
104.84
107.51
110.10
113.74
308.06
434.85
530.79
609.54
614.96
569.67
497.11
365.20
215.39
210.27
212.79
215.31
217.82
220.32
222.79
225.24
227.67
230.11
232.79
235.71
238.56
241.37
244.22
247.08
249.93
252.74
255.51
258.22
260.92
263.59
266.25
268.88
271.50
274.08
276.65
279.20
281.74
284.25
286.73
289.19
291.61
294.03
296.44
298.82
301.17
303.51
305.81
308.09
310.35
312.59
314.82
317.03
319.22
321.38
323.53
325.68
327.77
156.35
159.13
160.09
162.43
163.46
164.28
164.98
166.98
167.48
168.28
169.68
170.58
171.38
172.38
173.78
174.49
176.60
177.12
178.04
179.66
180.79
182.63
183.08
185.13
186.78
188.94
190.61
192.78
193.46
195.34
197.42
199.60
200.09
202.57
204.85
206.93
208.81
209.29
211.06
213.42
214.08
216.92
217.07
219.17
220.91
221.72
222.32
223.30
329.83
331.62
333.76
338.65
339.71
340.69
345.28
346.09
348.52
350.97
353.38
355.79
358.21
223.86
224.31
224.60
352.06
380.36
425.28
706.96
534.02
350.75
239.32
242.85
244.57
248.54
0.96
4.11
7.15
0.11
2.98
5.78
8.52
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
01.19
04.03
07.03
09.97
12.86
15.69
19.09
22.96
26.75
30.49
34.15
37.79
41.38
44.88
48.35
51.78
55.16
58.52
61.81
65.01
68.27
71.47
74.66
77.8
80.91
83.98
87.01
90.01
92.98
95.91
98.79
01.29
02.59
03.21
03.89
04.33
05.01
05.80
07.16
08.66

L.-G. Kong et al. / J. Chem. Thermodynamics 35 (2003) 1897–1904
1901
4
Cp;mðJ ꢀ Kꢁ ꢀ mol Þ ¼ 77:179 þ 24:686X ꢁ 2:9365X þ 4:9479X þ 8:8659X ;
1
ꢁ1
2
3
ð2Þ
where X ¼ ðT ꢁ 138Þ=60, and T is the absolute temperature. The correlation coef-
2
ficient of the fitted curve and R ¼ 0:9998.
In the temperature range of (211 to 333) K
C
p;mðJ ꢀ Kꢁ ꢀ mol Þ ¼ 185:61 þ 36:593X þ 19:319X ꢁ 3:0765X ꢁ 13:956X ;
1
ꢁ1
2
3
4
ð3Þ
2
where X ¼ ðT ꢁ 272Þ=62 and R ¼ 0:9996.
From figure 1, it can be seen that the heat capacities of the sample vary with in-
creasing temperature in a smooth and continuous manner from 78 K to 198 K and
from 211 K to 333 K. No thermal anomaly was observed in these temperature
ranges. Therefore, the sample is stable in the above temperature ranges. However,
thermal anomalies were observed in the temperature range from 199 K to 210 K
and from 334 K to 351 K. The peak temperatures at the highest point of the peaks
were found to be 204.33 K and 345.28 K, respectively. The two thermal anomalies
are ascribed to a solid–solid phase transition and solid–liquid phase transition,
respectively.
The molar enthalpy increments, DH , and the entropy increments, DS , of the two
m
m
phase transitions derived by the literature method [4] are for the solid–solid phase
ꢁ1
1
ꢁ1
transition, DH
m
¼ 2:57 kJ ꢀ molꢁ and DS
m
¼ 12:57 J ꢀ K ꢀ mol at 204.33 K, and,
¼ 3:07 kJ ꢀ mol and Dfus ¼ 8:89
ꢁ
1
for the solid–liquid phase transition, Dfus
H
m
S
m
ꢁ
1
ꢁ1
J ꢀ K ꢀ mol at 345.28 K. The melting point and the molar enthalpy of fusion of
2;6
exo-Tricyclo[5.2.1.0 ]decane, stereoisomer of the compound under study, are 182
K and 4.6 kJ ꢀ molꢁ [5], respectively. Although the two compounds are structurally
1
2;6
similar, the melting point of exo-Tricyclo[5.2.1.0 ]decane is far below that of
endo-Tricyclo[5.2.1.0 ]decane and the molar enthalpy of fusion of exo-Tricyclo-
2;6
2;6
2;6
[
5.2.1.0 ]decane is higher than that of endo-Tricyclo[5.2.1.0 ]decane.
3
.2. Thermodynamic functions
Through the polynomials of heat capacity and the relationship of thermodynamic
functions, the thermodynamic function data were calculated in the temperature
range from (80 to 330) K with a temperature interval of 5 K, based on the reference
temperature 298.15 K. The values of thermodynamic function H ) H298:15,
T
ST ) S298:15 are listed in table 2.
3
.3. The results of TG and DTG analysis
2;6
The TG and DTG curves of endo-Tricyclo[5.2.1.0 ]decane are shown in figure 2.
2;6
It can be seen that endo-Tricyclo[5.2.1.0 ]decane begins to lose weight at 300 K
and reaches the maximal rate of weight loss at 408 K. The sample completely loses
its weight when the temperature reaches 413 K. The product collected during the

1902
L.-G. Kong et al. / J. Chem. Thermodynamics 35 (2003) 1897–1904
Table 2
Calculated thermodynamic function data of endo-Tricyclo[5.2.1.0 ]decane
2
;6
T/K
Cp
H ꢁ H
kJ ꢀ mol
ST ꢁ S
T
298:15
ꢁ1
298:15
J ꢀ Kꢁ ꢀ molꢁ1
1
J ꢀ K ꢀ molꢁ1
ꢁ1
Solid–solid phase transition at 204.33 K
8
8
9
9
0
5
0
5
53.844
55.069
56.649
58.497
60.536
62.701
64.937
67.197
69.447
71.662
73.826
75.937
77.999
80.029
82.053
84.107
86.240
88.507
90.978
93.728
96.846
100.43
104.59
109.44
)29.150
)28.877
)28.598
)28.310
)28.013
)27.705
)27.386
)27.056
)26.714
)26.361
)25.997
)25.623
)25.238
)24.843
)24.438
)24.022
)23.597
)23.160
)22.711
)22.250
)21.773
)21.280
)20.768
)20.233
)149.95
)146.65
)143.45
)140.32
)137.27
)134.26
)131.3
)128.37
)125.47
)122.60
)119.75
)116.92
)114.12
)111.35
)108.59
)105.86
)103.15
)100.46
)97.78
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
00
05
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
)95.11
)92.43
)89.73
)87.01
)84.23
Solid–liquid phase transition at T ¼ 345.28 K
156.71
210
215
220
225
230
235
240
245
250
255
260
265
270
275
280
285
290
295
298.15
300
305
)15.718
)14.926
)14.118
)13.297
)12.465
)11.623
)10.772
)9.911
)9.042
)8.163
)7.273
)6.371
)5.456
)4.526
)3.581
)2.618
)1.638
)0.639
0.000
)62.06
)58.34
)54.62
)50.93
)47.27
)43.64
)40.06
)36.52
)33.01
)29.53
)26.07
)22.64
)19.21
)15.80
)12.39
)8.980
)5.570
)2.155
0.000
160.16
162.99
165.37
167.44
169.32
171.12
172.93
174.83
176.89
179.16
181.67
184.43
187.46
190.73
194.23
197.91
201.71
204.13
205.56
209.38
0.379
1.416
1.267
4.694

L.-G. Kong et al. / J. Chem. Thermodynamics 35 (2003) 1897–1904
1903
TABLE 2 (continued)
T/K
Cp
H ꢁ H
kJ ꢀ mol
T
298:15
ꢁ1
ST ꢁ S
298:15
J ꢀ Kꢁ ꢀ molꢁ1
1
J ꢀ K ꢀ molꢁ1
ꢁ1
Solid–solid phase transition at 204.33 K
3
3
3
3
3
10
15
20
25
30
213.06
216.48
219.52
222.02
223.82
2.473
3.546
4.637
5.741
6.856
8.127
11.56
15.00
18.42
21.83
100
80
60
40
20
0
2
TG
DTG
C10H16
0
280
300
320
340
360
380
400
420
440
FIGURE 2. Thermogravimetric analysis (TG) and differential thermal analysis (DTG) curve of endo-
Tricyclo[5.2.1.0 ]decane.
2;6
heating until 425 K proves to be the same substance as the initial sample judging
from its color, melting point and morphology. Considering that endo-Tricy-
2;6
clo[5.2.1.0 ]decane is in solid state at room temperature and melts at 345.236 K,
2
;6
we can deduce that endo-Tricyclo[5.2.1.0 ]decane sublimes before melting at first
and then melts with subliming as the temperature increases. When the temperature
2
;6
reaches 423.15 K, endo-Tricyclo[5.2.1.0 ]decane completely changes into vapor un-
der the present experimental conditions.
Acknowledgements
The authors gratefully acknowledge the National Natural Science Foundation of
China for financial support to this work under Grant No. 20073047.

1904
L.-G. Kong et al. / J. Chem. Thermodynamics 35 (2003) 1897–1904
References
[
[
1] J. Yang, Z.T. Mi, C. Liu, Petrochem. Technol. 27 (1998) 475–478.
2] Z.C. Tan, G.Y. Sun, Y. Sun, A.X. Yin, W.B. Wang, J.C. Ye, L.X. Zhou, J. Therm. Anal. 45 (1995) 59–
6
7.
3] D.A. Ditmars, S. Ishihara, S.S. Chang, G. Bernstein, E.D. West, J. Rev. Natl. Bur. Stands. 87 (1982)
59–163.
[
1
[
[
4] B. Xue, Z.C. Tan, S.W. Lu, S.H. Meng, X.H. Yuan, Acta Chim. Sinica 57 (1999) 881–886.
5] C.T. Moynihan, H. Sasabe, D.S. Czaplak, U.E. Schnaus, J. Chem. Eng. Data 23 (1978) 107–111.
JCT 03/040