Investigation of thermodynamic properties of trans-2-cyclohexylcyclohexanol

Article abstract of DOI:10.1006/jcht.1997.0189

A comprehensive study of thermodynamic properties of trans-2-cyclohexylcyclohexanol (t-2CCOL) was carried out in this work. The subject compound is a by-product from the synthesis of 2-phenylphenol. The standard molar enthalpy of combustion of t-2CCOL, found by the bomb calorimetry method, Δ_cH^o_m(cr,298.15 K) = - (7388.05 ± 1.37) kJ·mol^-1, and the standard molar enthalpy of formation Δ_fH^o_m(cr,298.5 K) = - (478.25 ± 2.13) kJ·mol^-1. The molar sublimation and vaporization enthalpies of t-2CCOL were measured with a heat-conduction differential microcalorimeter: Δ^g_crH^o_m(319.5 K) = (98.56 ± 0.52) kJ·mol^-1; Δ^g_JH^o_m(345.8 K) = (80.31 ± 0.34) kJ·mol^-1. Vapour pressure of t-2CCOL was measured by the integral effusion Knudsen method in the temperature range 293 K to 325 K for crystal: ln(p/Pa) = (37.30 ± 0.22) - (11616 ± 69)·T^-1, and in the temperature range 328 K to 364 K for liquid: ln(p/Pa) = (34.41 ± 0.44) - (10013 + 150)·T^-1. The heat capacity of t-2CCOL was measured by the vacuum adiabatic calorimetry (T = 5 K to T = 338 K). The fusion temperature of t-2CCOL is 325.8 K, and the molar enthalpy of fusion is Δ_fusH^o_m = (14.515 ± 0.029) kJ·mol^-1. Standard molar thermodynamic functions of t-2CCOL in the crystalline state at T = 298.15 K were obtained on the basis of these measurements: C^o_p,m = (248.68 ± 0.99); Δ^T₀S^o_m = (263.85 ± 1.18); Δ^T₀H^o_m/T = (130.52 ± 0.51); Φ^o_m = (133.33 ± 1.29) J·K^-1·mol^-1.

Full text of DOI:10.1006/jcht.1997.0189

J. Chem. Thermodynamics 1997, 29, 687–699
Investigation of thermodynamic properties of
trans-2-cyclohexylcyclohexanol
Yu. V. Maksimuk, G. J. Kabo,a A. A. Kozyro,
V. V. Simirsky, A. P. Krasulin, and V. M. Sevruk
Institute for Physical and Chemical Research, Belarussian State University,
Leningradskaya 14, Minsk 220080, Republic Belarus
A
comprehensive study of thermodynamic properties of trans-2-cyclohexylcyclohexanol
(t-2CCOL) was carried out in this work. The subject compound is a by-product from the
synthesis of 2-phenylphenol. The standard molar enthalpy of combustion of t-2CCOL, found
by the bomb calorimetry method, DcHm°(cr,298.15 K) = − (7388.05 2 1.37) kJ·mol−1, and the
standard molar enthalpy of formation DfHm°(cr,298.5 K) = − (478.25 2 2.13) kJ·mol−1. The
molar sublimation and vaporization enthalpies of t-2CCOL were measured with
a
g
heat-conduction differential microcalorimeter: DcrHm°(319.5 K)
= ;
(98.56 2 0.52) kJ·mol−1
g
Dl Hm°(345.8 K) = (80.31 2 0.34) kJ·mol−1. Vapour pressure of t-2CCOL was measured by the
integral effusion Knudsen method in the temperature range 293 K to 325 K for crystal:
ln(p/Pa) = (37.30 2 0.22) − (11616 2 69)·T−1, and in the temperature range 328 K to 364 K for
liquid: ln(p/Pa) = (34.41 2 0.44) − (10013 2 150)·T−1. The heat capacity of t-2CCOL was
measured by the vacuum adiabatic calorimetry (T = 5 K to T = 338 K). The fusion temperature
of t-2CCOL is 325.8 K, and the molar enthalpy of fusion is DfusHm° = (14.515 2 0.029) kJ·mol−1
.
Standard molar thermodynamic functions of t-2CCOL in the crystalline state at T = 298.15 K
were obtained on the basis of these measurements: Cp°,m (248.68 2 0.99);
=
T
T
0
D Sm° = (263.85 2 1.18); D Hm°/T = (130.52 2 0.51); F° = (133.33 2 1.29) J·K−1·mol−1. 7 1997
m
0
Academic Press Limited
KEYWORDS: trans-2-cyclohexylcyclohexanol; heat capacity; entropy; enthalpy of formation;
saturated vapour pressure
1. Introduction
2-cyclohexylcyclohexanol is formed as a by-product of the industrial hydrogenation
of phenol(1) to obtain cyclohexanol, and of oxidation of cyclohexanone.(2) In addition,
2-cyclohexylcyclohexanol is also a semi-product in the industrial synthesis of
2-phenylphenol.(3) All these facts necessitate a comprehensive study of the
thermodynamic properties of 2-cyclohexylcyclohexanol, which is important to
analyse the methods of its synthesis and processing.
It is known that cyclohexylcyclohexane(4) and cyclohexanol,(5) which have similar
structures, are characterized by complex thermal behaviour in the crystalline state.
Cyclohexanol forms a plastic crystal in the temperature range 265.5 K to 299.05 K
°
and has a low fusion entropy typical for plastic crystals {DfusSm(299.05 K) =
5.96 J·K−1·mol−1}. According to the results(4) of the d.s.c. investigations
cyclohexylcyclohexane forms four crystalline phases at the temperatures from 256 K
a To whom correspondence should be addressed.
0021–9614/97/060687 + 13 $25.00/0/ct970189
7 1997 Academic Press Limited

688
Yu. V. Maksimuk et al.
to 278 K, but it has a higher fusion entropy {DfusS°(277.2 K) = 24.26 J·K−1·mol−1}
than the majority of plastic crystals. The investigation of i.r. and Raman spectra of
cyclohexylcyclohexane at different temperatures(6) showed that solid-to-solid
transformations are accompanied by considerable changes in conformational
composition and molecular symmetry (C2h to C2). The study of low-temperature heat
capacity and measurement of phase transition enthalpies in 2-cyclohexylcyclohexanol
also permits estimation of to what extent crystal polymorphism of different
compounds can be predicted from simple structure analogies for molecules.
2. Experimental section
Trans-2-cyclohexylcyclohexanol was synthesized by the following manner:
The starting reactant cyclohexanone was condensed under atmospheric pressure
at T = 373 K in 5 mass per cent NaOH solution.(7) The obtained mixture 40.9x·2-(1'-
cyclohexenyl)cyclohexanone(I) + 0.1x·2-(1-cyclohexyliden)cyclohexanone(II)5 was
hydrogenated in the autoclave at p = 11.15 MPa and T = 373 K using 0.5 mass per
cent Pt on the graphite as a catalyst. The hydrogenation products (0.9x·trans-2-
cyclohexylcyclohexanol + 0.06x·cis-2-cyclohexylcyclohexanol + 0.04x·impurities)
were crystallized for a long time. The separation of the trans-isomer was made at
consecutive seven-fold recrystallizations from petrol ether (fraction boiling in the
temperature range from 313 K to 323 K). The final purification of sample was carried
out in a sublimator at p = 0.4 kPa and T = 350 K. Vapour was condensed on the
surface of a glass trap, forming crystals. The trap was cooled by water. The purest
middle crystal fractions were taken for measurements.
The relative content of components in mixtures was determined by gas
chromatograph CHROM-5 (carrier gas N2) with a flame ionization detector. The
condensation products were analysed using a glass column (1.7 m long, 4 mm i.d.),
filled with polysorb W on 30 per cent PPMS. The 2-cyclohexylcyclohexanol
diastereomers were separated in steel column (3 m long, 4 mm i.d.), containing 5 per
cent polyethylene glycol-1500 on inerton AV-DMCS. The mass fraction purity of
2-cyclohexylcyclohexanol was 0.9948 of the trans-isomer and 0.0052 of the cis-isomer
according to chromatographic analysis. We found, on the basis of gravimetric
analysis of combustion products in a calorimetric bomb, that the total mass fraction
of isomers was (0.9996 2 0.0005). Prior to use, the samples were kept in a desiccator

Thermodynamic properties of trans-2-cyclohexylcyclohexanol
689
over P2O5. The density of crystalline sample d = 0.987 g·cm−3 at T = 293 K was
determined by the picnometric method using as a reference liquid the saturated
solution of the studied sample in petrol ether.
The low-temperature heat capacity was measured in the vacuum adiabatic
calorimeter TAU-1, fabricated by VNIIFTRI (National Scientific and Research
Institute for Physical-technical and Radio-technical Measurements) in Moscow. The
studied sample (m = 0.46212 g) was put into a stainless steel container filled with
heat-exchange helium gas and sealed with an indium gasket. The container was
tightly inserted into the calorimetric sleeve and provided with a manganin heater. The
sleeve was suspended by three nylon cords within the adiabatic shield, which was also
provided with a manganin heater. The temperature difference between the adiabatic
shield and the calorimetric sleeve was determined by a four-junction differential
thermocouple: 4(0.999 Cu + 0.001 Fe)-to-Chromel5. The electric potential of the
thermocouple after preliminary amplification went to the terminals of an analogue
regulation block, which assured automatic adiabatic shield control with proportional
integral/differential action. The thermometric measurements were made by a capsule
type (iron + rhodium) resistance thermometer (Ro = 45.32 V) installed on the inner
surface of the adiabatic shield. The thermometer was fabricated and calibrated by
VNIIFTRI. The reliability of the calorimetric apparatus was established by
measuring the heat capacities of standard benzoic acid K-1 and high-purity copper.
The probable error of the heat capacity values is considered to be 0.4 per cent at
the temperatures 40 K to 321 K; this error increases at T Q 40 K and it is 2 per cent
at the helium temperatures.
The sublimation and vaporization enthalpies were determined in a differential heat
conducting microcalorimeter of Calvet type using special calorimetric cells. A
detailed description of the cells appears elsewhere.(8) The investigated samples
4m = (0.040 to 0.075 g)5 were put into stainless steel hermetic ampoules supplied with
an aluminium membrane. After preliminary thermostatting of the calorimeter the
membrane was pierced by a special demountable rod and a heating flux needed for
evaporation was recorded. The calorimeter was calibrated by sublimation of benzoic
acid (trade mark K-1), naphthalene (twice sublimed from the sample ‘‘pure for
analysis’’) and by vaporization of n-decane (sample ‘‘for chromatographic analysis’’),
twice-distilled water. As a result it was found that the evaporation enthalpy
measurement error does not exceed 1.0 per cent.
The saturated vapour pressure over crystalline and liquid trans-2-
cyclohexylcyclohexanol was determined by integral effusion Knudsen method. The
sample was located in a stainless steel chamber, which was sealed with a Teflon
gasket. The chamber was placed in a copper block, which was placed in a water
thermostat. The thermostatting accuracy was within 0.005 K. The temperature was
measured with accuracy of 0.01 K by a Pt-resistance thermometer using the
potentiometric method. The copper block was filled with heat exchange gas helium
to accelerate the establishment of thermal equilibrium. At the beginning of the
experiment helium was pumped out, and the sample mass diminution during the
non-steady evaporation period was determined by the method described earlier.(9)
Membranes of nickel foil with thickness 0.05 mm and diameters of effusion orifices

690
Yu. V. Maksimuk et al.
0.8254 mm and 0.2453 mm were used in experiments with crystal and liquid,
respectively. The correction coefficients k to calculate saturated vapour pressure p
from Knudsen pressure data pk, according to the equation p = k·pk, were found in
preliminary experiments using membranes with different effusion orifice diameters.(10)
Errors in measurements of saturated vapour pressure did not exceed 5 per cent, as
it was established on the base of comparison of our result for urea and benzoic
acid with reliable literature data.(11, 12) The saturated vapour pressure of
trans-2-cyclohexylcyclohexanol in the studied temperature range 293 K to 364 K
being rather low (p Q 130 Pa), the equilibrium of reaction ‘‘monomer-associates’’ is
almost completely displaced to the side of the monomer. That is why, from
calculating the Knudsen vapour pressure, we supposed that the vapour has a
monomolecular composition.
The combustion enthalpy was determined in two bomb calorimeters with
isothermal shields. Their temperatures were maintained constant within 2 0.0015 K.
The measurements error for combustion energies is 0.02 per cent.(13) The calorimetric
bomb was filled with purified oxygen under pressure 3.04 MPa. Thermometric
measurements were carried out by the 100 V Pt-resistance thermometers with
recording of amplified signal by digital voltmeter. The compound was burnt in the
form of tablets pressed in the air without auxiliary substances. Samples were ignited
by passing electrical current from a capacitor battery, (capacity = 0.01 F) through
a
platinum wire (diameter = 0.05 mm). Energy equivalents of calorimeters
(14954.2 2 5.6) J·K−1 and (14938.6 2 5.3) J·K−1 were determined from a reference
sample of benzoic acid (trade mark K-1) with combustion energy =
− (26434.6 2 4.5) J·g−1 based on weight in a vacuum. The sample masses were
reduced to vacuum, taking into consideration the density value of crystalline
trans-2-cyclohexylcyclohexanol. The completeness of combustion was checked by
gravimetric analysis of combustion products using the Rossini method.(14) The
Washburn corrections were calculated by the Prosen method and recommendations
given in reference 15. The molar mass of trans-2-cyclohexylcyclohexanol
(M = 182.3052 g·mol−1) was evaluated from the relative atomic masses of
elements.(16)
3. Thermodynamic properties of trans-2-cyclohexylcyclohexanol
Experimental heat capacity Cs,m values of crystalline trans-2-cyclohexylcyclohexanol,
measured in five experimental series in the temperature range from 5.10 K to
337.73 K are represented in table 1. To extrapolate the heat capacity to T Q 5 K the
Debye equation was used:
C
s,m = 3·R·D·(uD·T−1),
(1)
where the characteristic temperature uD = 68.2 K was obtained from experimental
measurements of Cs,m between T = 5.10 K and T = 12.72 K.
No anomaly was discovered on the Cs,m = f(T) curve (figure 1) in the whole
temperature interval studied, excluding the fusion region.

Thermodynamic properties of trans-2-cyclohexylcyclohexanol
691
TABLE 1. Experimental molar heat capacities Cs,m at vapour saturation pressure for
trans-2-cyclohexylcyclohexanol
in
temperature
range
DT
and
at
mean
temperature
ꢀTꢁ(R = 8.31451 J·K−1·mol−1
)
ꢀTꢁ
K
Cs,m
R
DT
K
ꢀTꢁ
K
Cs,m
R
DT
K
Series 1
0.0971
0.121
0.131
0.151
0.170
0.195
0.217
0.238
0.261
0.273
0.315
0.333
0.362
0.390
0.418
0.449
0.490
0.563
0.602
0.633
0.691
0.712
0.750
0.806
0.843
0.901
0.933
0.984
1.079
1.149
1.176
1.263
1.327
1.390
1.457
1.508
1.564
1.647
1.704
1.805
1.902
1.947
2.024
2.103
2.167
2.260
2.331
2.446
2.550
2.680
2.781
2.916
25.08
3.042
3.163
3.270
3.426
3.531
3.668
Series 2
4.024
4.186
4.375
4.553
Series 3
2.755
2.894
3.351
3.518
3.703
4.227
4.445
4.624
4.838
5.002
5.196
5.393
5.534
5.667
5.926
6.107
6.311
6.498
6.752
6.968
7.212
7.419
7.690
7.955
8.255
8.561
9.093
9.344
9.602
9.854
10.10
10.35
10.64
10.97
11.28
11.56
11.93
12.32
12.69
13.04
13.37
0.76
0.90
0.85
0.80
0.77
0.73
5.10
5.45
5.64
5.84
6.09
6.37
6.63
6.88
7.18
7.34
7.59
7.86
8.10
8.33
8.58
8.84
9.14
0.18
0.16
0.21
0.20
0.29
0.27
0.25
0.24
0.22
0.21
0.28
0.25
0.23
0.22
0.27
0.26
0.32
0.28
0.27
0.25
0.24
0.23
0.34
0.32
0.31
0.30
0.29
0.43
0.39
0.36
0.36
0.45
0.42
0.41
0.39
0.38
0.36
0.50
0.48
0.46
0.44
0.42
0.41
0.39
0.38
0.56
0.54
0.51
0.70
0.66
0.85
0.80
25.92
26.81
27.64
28.44
29.19
31.41
32.45
33.55
34.59
0.95
1.13
1.06
1.01
23.27
24.13
27.23
28.28
29.33
32.73
34.02
35.36
36.75
38.18
39.65
41.04
42.52
44.08
45.71
47.41
49.00
50.71
52.54
54.51
56.60
58.79
61.11
63.72
66.57
69.28
74.33
76.93
79.68
82.22
84.59
87.35
90.48
93.50
96.72
100.12
103.82
107.81
111.68
115.43
119.08
0.88
0.82
1.08
1.01
1.06
1.33
1.24
1.42
1.33
1.51
1.42
1.34
1.61
1.52
1.73
1.63
1.54
1.86
1.79
2.14
2.02
2.35
2.27
2.93
2.77
2.63
2.41
2.80
2.69
2.39
2.33
3.19
3.07
2.97
3.45
3.34
4.06
3.92
3.80
3.70
3.60
9.76
10.04
10.30
10.55
10.79
11.08
11.42
11.75
12.06
12.35
12.72
13.13
13.51
13.88
14.29
14.73
15.15
15.55
15.94
16.31
16.75
17.25
17.72
18.17
18.61
19.02
19.43
19.82
20.30
20.85
21.38
22.00
22.69
23.46
24.29

692
Yu. V. Maksimuk et al.
TABLE 1—continued
ꢀTꢁ
K
Cs,m
R
DT
K
ꢀTꢁ
K
Cs,m
R
DT
K
Series 4
13.58
13.91
14.27
14.55
14.63
14.82
15.15
15.32
15.96
16.29
16.50
16.79
Series 5
17.11
17.40
17.67
18.39
18.67
18.98
19.29
19.51
19.81
20.14
20.47
21.18
212.20
215.92
219.62
223.63
227.94
232.22
236.47
240.70
244.91
249.09
253.25
257.39
261.51
265.71
269.71
273.79
277.86
281.92
285.97
290.01
21.52
21.89
22.23
22.63
23.01
23.39
23.87
24.29
24.64
25.08
25.50
25.93
26.32
26.74
27.15
27.61
27.91
28.34
28.71
29.12
Series 6
50.89
51.39
51.65
52.11
52.65
3.69
3.66
3.62
4.26
4.22
4.19
4.15
4.11
4.08
4.05
4.02
3.98
3.95
3.92
3.90
3.86
3.84
3.82
3.79
3.77
122.30
125.76
129.15
132.47
133.95
135.74
138.92
142.06
148.19
151.19
154.08
157.22
3.50
3.42
3.36
3.29
3.26
3.21
3.15
3.11
3.07
2.96
2.84
3.43
159.68
163.22
166.71
173.57
177.29
181.31
185.29
189.23
193.14
197.02
200.86
208.44
3.55
3.51
3.47
3.39
4.94
3.98
3.94
3.91
3.86
3.83
3.79
3.72
328.26
330.95
332.35
334.83
337.74
3.05
3.60
3.61
3.58
3.56
Smoothing of experimental heat capacity values was realized with following
polynomials:
n
Cs,m(T) = s ai·Ti.
(2)
i = 0
To diminish the error at smoothing experimental results the whole temperature range
was divided into six intervals. The coefficient values of ai, calculated by the method
of least squares for all temperature intervals, are given in table 2. In the overlapping
regions of temperature intervals the Cs,m values, calculated from the coefficient of the
polynomials for preceding and subsequent intervals coincided within
0.05 J·K−1·mol−1. The linear extrapolation of heat capacity of solid and liquid phases
in the heterogeneous region was carried out on the basis of heat capacity
measurements at temperatures from 275 K to 290 K, and from 330 K to 340 K,
respectively.
The thermodynamic fusion parameters were obtained by averaging
three experimental determinations: Tfus
=
(325.80
2
0.05) K, DfusHm°
=
(14515 2 29) J·mol−1, and DfusSm° = (44.55 2 0.20) J·K−1·mol−1.
Thermodynamic functions of trans-2-cyclohexylcyclohexanol in the range from
T:0 to T = 335 K (table 3) were calculated on the basis of smoothing polynomials

Thermodynamic properties of trans-2-cyclohexylcyclohexanol
693
FIGURE 1. Experimental molar heat capacity Cs,m of trans-2-cyclohexylcyclohexanol in condensed
state.
for the heat capacity. At temperature 298.15 K molar heat capacity Cp°,m, entropy
T
T
D0 Sm°, enthalpy D0 Hm°·T−1, and molar Gibbs free energy function
T
T
F°
=
D0 Sm°
−
D0 Hm°·T−1 for crystalline trans-2-cyclohexylcyclohexanol
m
are:
(248.68
2
0.99) J·K−1·mol−1,
(263.85
2
1.18) J·K−1·mol−1,
(130.52 2 0.51) J·K−1·mol−1, and (133.33 2 1.29) J·K−1·mol−1, respectively.
Calorimetric measurements of sublimation and vaporization enthalpies of
trans-2-cyclohexylcyclohexanol are given in table 4. The average values of
sublimation and vaporization enthalpies, determined from six experiments,

694
Yu. V. Maksimuk et al.
g
g
are: DcrHm°(319.5 K)
=
(98.56 2 0.52) kJ·mol−1 and Dl Hm°(345.8 K)
=
(80.31 2 0.34) kJ·mol−1. Conversion of these values to fusion temperature
g
Tfus
=
325.8 K gives: DcrHm°(325.80 K)
=
(98.47 2 0.52) kJ·mol−1 and
g
Dl Hm°(325.80 K) = (83.73 2 0.34) kJ·mol−1. The fusion enthalpy DfusHm°(325.80 K) =
(14.74 2 0.62) kJ·mol−1 was obtained on the basis of Hess’s law. This value,
determined indirectly is in satisfactory agreement with the result of direct
measurements: DfusHm°(325.80 K) = (14.515 2 0.029) kJ·mol−1.
The experimental values of saturated vapour pressure over crystalline and liquid
trans-2-cyclohexylcyclohexanol at temperatures from 293 K to 325 K and from
328 K to 364 K, respectively, are represented in table 5. The experimental results
fitted by the least-squares method can be approximated for crystal by the equation:
ln(p/Pa) = (37.30 2 0.22) − (11616 2 69)·(T/K)−1,
(3)
and for liquid:
ln(p/Pa) = (34.41 2 0.44) − (10013 2 150)·(T/K)−1.
(4)
The thermodynamic parameters of sublimation and vaporization at the
average temperatures of the measurements, obtained from equations (3) and (4)
g
g
respectively, are: DcrHm°(309.1 K)
=
(96.58 2 0.57) kJ·mol−1 DcrSm°(309.1 K) =
g
(214.3 2 1.9) J·K−1·mol−1, Dl Hm°(346.1 K)
=
(83.25 2 1.25) kJ·mol−1, and
g
Dl Sm°(346.1 K) = (156.3 2 3.6) J·K−1·mol−1. Conversion of the sublimation enthalpy,
found by calorimetric method, to the temperature T = 309 K with allowance for the
temperature dependence of the heat capacities of crystalline and gaseous phases gives
g
the value: DcrHm°(309 K) = (98.78 2 0.52) kJ·mol−1.
For the following thermodynamic calculations the weighted average sublimation
g
enthalpy value at T = 309 K was used: DcrHm°(309 K = (97.78 2 0.77) kJ·mol−1,
found from both these results. This value was converted to the temperature 298.15 K,
g
DcrHm°(298.15 K) = (98.01 2 0.77) kJ·mol−1.
The standard molar entropy of C12H22O(g) at T = 309 K: Sm°(g, 309 K) =
(491.1 2 2.8) J·K−1·mol−1 was derived from the entropy of the crystalline phase at
T = 309 K, the weighted average sublimation enthalpy value and the vapour pressure
at T = 309 K.
TABLE 2. Values of polynomials coefficients (ai) to describe the temperature dependence of heat capacity
of trans-2-cyclohexylcyclohexanol
Temperature interval
ai
(5 to 25) K (20 to 80) K (75 to 180) K (180 to 275) K (275 to 290) K (330 to 340) K
a0
a1
a2
−1.0214
0.6130
−0.1728
3.4885
−24.760
80.334
9.0698
−1.1698
0.1351
−0.3321
0.3626
−260.42
18.630
−0.4872
0.7248
−0.6302
0.3190
−0.8692
0.9839
548.24
6.4738
0.8124
−84.118
1.5453
−7.5204
0.04783
−0.01215
0.00115
a3·102
a4·104
a5·106
−0.1481
a6·109 −997.85
a7·1012

Thermodynamic properties of trans-2-cyclohexylcyclohexanol
695
T
T
TABLE 3. Standard molar thermodynamic functions Cp,m, D0 Hm°, D0 Sm°, F°m for crystalline and liquid
trans-2-cyclohexylcyclohexanol (R = 8.31451 J·K−1·mol−1
)
T
T
a
T
K
Cp°,m
R
D0 Hm°
D0 Sm°
F°
R
m
RT
R
0
5
10
15
20
25
30
35
40
45
50
60
70
80
90
0.0000
0.0930
0.6005
1.363
2.196
3.019
3.811
4.558
5.242
5.867
6.447
7.549
8.650
9.635
10.62
11.58
12.51
13.42
14.31
15.22
16.15
17.09
18.01
18.84
19.58
20.42
21.31
22.25
23.22
24.20
25.19
26.17
27.15
28.14
29.11
29.91
30.09
31.07
32.04
32.61
50.48
51.22
52.14
0.0000
0.0000
0.0000
0.0077
0.0598
0.1757
0.3459
0.5572
0.7984
1.061
1.340
1.629
1.926
2.531
3.143
3.757
4.368
4.975
5.577
6.174
6.764
7.349
7.929
8.503
9.073
9.638
10.20
10.76
11.31
11.85
12.40
12.94
13.48
14.01
14.55
15.08
15.61
16.04
16.13
16.66
17.18
17.49
17.49
17.77
18.12
0.0231
0.1684
0.4362
0.7707
1.140
1.519
1.901
2.276
2.641
2.993
3.661
4.295
4.903
5.484
6.046
6.592
7.124
7.642
8.151
8.653
9.151
9.645
10.13
10.61
11.08
11.55
12.01
12.48
12.95
13.42
13.89
14.36
14.83
15.31
15.70
15.79
16.26
16.74
17.02
22.38
22.74
23.17
0.0308
0.2283
0.6119
1.117
1.697
2.318
2.962
3.616
4.270
4.919
6.192
7.438
8.660
9.852
11.02
12.17
13.30
14.41
15.50
16.58
17.65
18.72
19.77
20.81
21.84
22.85
23.87
24.88
25.89
26.89
27.90
28.91
29.91
30.92
31.73
31.92
32.92
33.92
34.50
39.86
40.52
41.29
100
110
120
130
140
150
160
170
180
190
200
210
220
230
240
250
260
270
280
290
298.15
300
310
320
325.80(cr)
325.80(l)
330
335
T
T
a F° = D Sm° − D Hm°·T−1
.
m
0
0
The results of the combustion experiments are summarized in table 6. The standard
molar energy of combustion DcUm° and standard molar enthalpy of
combustion DcHm° were calculated, according to the reaction:
C12H22O(cr) +17O2(g) = 12CO2(g) + 11 H2O,
(5)

696
Yu. V. Maksimuk et al.
where DcUm°
=
− (7375.65 2 1.37) kJ·mol−1 and DcHm°
=
− (7388.05 2
1.37) kJ·mol−1.
As
a result, the standard molar enthalpy of formation of crystalline
trans-2-cyclohexylcyclohexanol
was
determined:
DfHm°(cr,298.15 K)
=
− (478.25 2 2.13) kJ·mol−1. The standard molar enthalpies of formation CO2(g)
and H2O(1) taken from reference 17 were used for the calculation. Taking into
account the entropy of crystalline trans-2-cyclohexylcyclohexanol, its sublimation
enthalpy and literature data for entropies of elements,(17) it was found that
DfGm°(cr,298.15 K)
=
− (77.59 2 2.83) kJ·mol−1, and DfHm°(g,298.15 K)
=
− (380.24 2 2.27) kJ·mol−1.
4. Some regularities in entropies of phase transitions of cyclohexylcyclohexane
derivatives
Thermodynamic functions of solid-to-solid transitions and fusion for compounds
with a similar structure are represented in table 7. Trans-2-cyclohexylcyclohexanol,
in contrast to cyclohexanol and cyclohexylcyclohexane, does not possess
solid-to-solid transitions.
TABLE 4. Calorimetric results for the sublimation and evaporation of trans-2-cyclohexylcyclohexanol.
g
g
The sublimation and evaporation enthalpy DH of a specimen and the molar enthalpies DcrHm° and Dl Hm°
were calculated from the expression:
t = t
DH = K−1
·
2DEdt; DHm° = DH·M·m−1
g
t = 0
where m is the specimen mass corrected to vacuum; M is the molar mass; K is the calorimeter constant;
DE is the thermocouple potential difference corresponding to the temperature imbalance between cell and
calorimeter thermostat at the time t; t2 is the experiment duration; T is the temperature of the calorimeter
g
m
g
T
K
t2
s
K·DH
mV·s
DH
J
Dcr, lHm°
Type
of cell
N
kJ·mol−1
1
2
3
4
5
6
0.07461
0.03972
0.04081
0.05064
0.04360
0.05195
319.4
319.4
319.5
319.3
319.4
319.6
10175
7945
7230
8445
7055
7840
7728.9
4158.2
4285.5
5152.4
4444.9
5273.9
B
B
B
A
A
A
39.948
21.492
22.149
27.427
23.661
28.073
97.61
98.64
98.94
98.74
98.93
98.52
g
DcrHm°(319.5 K)ꢁ = (98.56 2 0.52) kJ·mol−1
1
2
3
4
5
6
0.06536
0.06857
0.06593
0.06535
0.05381
0.07458
346.5
345.2
346.0
346.3
344.9
345.9
5915
5165
5580
4985
4225
4800
5363.6
5587.0
5379.4
5271.2
4297.0
5981.2
A'
A'
A'
B'
B'
B'
28.934
30.140
29.020
28.922
23.576
32.817
80.71
80.13
80.24
80.68
79.87
80.22
g
Dl Hm°(345.8 K)ꢁ = (80.31 2 0.34) kJ·mol−1
The
K
values for cells A, B, A', and B' were: (187.86, 193.48, 185.37, and
182.26) mV·s: J−1, respectively. Uncertainties of the enthalpies were estimated with allowances for the
Student coefficient t = 2.571 for 95 per cent confidence interval.

Thermodynamic properties of trans-2-cyclohexylcyclohexanol
697
TABLE 5. The experimental values of saturated vapour pressure p for trans-2-cyclohexylcyclohexanol.
Dm and t are the decrease in specimen mass and the duration of each experiment, respectively
T
K
p
Pa
106·Dm
Kg
t
s
Crystal
293.27
298.16
302.91
308.40
313.19
318.44
322.45
324.87
0.091
0.175
0.316
0.639
1.12
2.07
3.28
7.46
8.73
7.81
12.75
13.65
25.09
19.90
17.36
47334
28854
14454
11754
7264
7269
3654
4.28
2454
Liquid
328.29
333.21
338.18
343.61
348.39
353.35
358.23
363.87
6.58
10.7
16.3
26.3
39.4
59.7
86.1
8.09
10.12
11.53
14.38
16.85
18.54
27.45
29.97
9354
7254
5454
4254
3354
2454
2534
1854
130
It should be noted that the values of fusion entropy for cyclohexylcyclohexane
derivatives are very different, and lie within the bounds of 24.45 J·K−1·mol−1 and
65.02 J·K−1·mol− 1. A considerably greater constancy is observed for S (the sum of
the entropies of all the phase transitions between low-temperature crystal and liquid).
The lower value of the above-mentioned sum for trans-2-cyclohexylcyclohexanol is
a characteristic of cyclic alcohols. It is confirmed by the values of S for cyclohexane
and its derivatives, given in table 7. Probably, the transition from ‘‘rigid’’
TABLE 6. Experimental determination of the standard massic energy of combustion Dcum° of crystalline
trans-2-cyclohexylcyclohexanol at T = 298.15 K, where m is the mass of the substance; d is the correction
for the heat exchange between the calorimeter vessel and surroundings; K is the cooling constant of the
calorimeter; DT is the corrected temperature rise; qi is the correction for ignition; q(HNO3) is the correction
for nitric acid formation; Sq is the sum of the Washburn corrections
m
g
d
K
K·103
DT
K
qi
J
q(HNO3)
Sq
J
− Dcum°
N
−
A−1
J
J·g−1
1
2
3
4
5
6
7
8
0.42601
0.42399
0.43069
0.46400
0.41427
0.45487
0.56027
0.46418
0.048
0.056
0.050
0.034
0.040
0.037
0.023
0.043
1.05
1.07
1.06
1.11
1.08
1.09
1.07
1.10
1.1543
1.1483
1.1673
1.1673
1.1227
1.2331
1.5175
1.2572
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
7.2
6.6
7.3
8.1
7.5
8.7
13.7
11.2
5.4
5.3
5.4
6.0
5.2
5.8
7.5
6.0
40441.9
40466.4
40452.9
40468.6
40449.7
40460.6
40461.0
40460.8
40457.7 J·g−1
The average square deviation of the average arithmetic value = 3.2 J·g−1
.

698
Yu. V. Maksimuk et al.
TABLE 7. Thermodynamic properties of solid-to-solid transitions and fusion of cyclohexane and some of its derivatives
(R = 8.31451 J·K−1·mol−1). S is the sum of entropies of all phase transitions between low-temperature crystal and liquid
Phase transitions
S
R
Compound
Property
References
crIV–crIII
crIII–crII
crII–crI
crI–liq
cyclohexylcyclohexane
T/K
DHm/R
DSm/R
256.1
185.2
0.72
267.5
89.0
0.33
273.5
851.5
3.11
277.2
815.4
2.94
4
7.11
5.36
7.82
trans-2-cyclohexylcyclohexanol
2-cyclohexylcyclohexanone
2-(1'-cyclohexenyl)cyclohexanone
cyclohexane
T/K
DHm/R
DSm/R
325.8
1746
5.36
this work
T/K
DHm/R
DSm/R
277.0
2165
7.82
18
18
19
5
T/K
DHm/R
DSm/R
278.8
2076
7.45 a 7.45
T/K
DHm/R
DSm/R
186.09
810.6
4.36
279.694
322.0
1.15
5.51
4.72
5.37
cyclohexanol
T/K
DHm/R
DSm/R
265.50
1062
299.05
214.4
0.72
4.00
cyclohexanone
T/K
DHm/R
DSm/R
220.83
1042
245.21
159.7
0.65
20
4.72
a
DtrsSm + DfusSm.
crystal to liquid in cyclohexanol and in trans-2-cyclohexylcyclohexanol is
accompanied by the formation of associated species in a liquid phase, leading to a
significant reduction in entropy of liquid cyclic alcohols at a temperature near Tfus.
An additive diminution of the liquid entropy for trans-2-cyclohexylcyclohexanol, in
comparison with cyclohexanol, is probably caused by the restriction of internal
rotation of the C6H11-tops in association, or by the formation of intramolecular
H-bonds.
The authors express their thanks to the International Science Foundation ISF (Grant
MW 4000) and Foundation of Fundamental Research of the Republic of Belarus
(Grant MP 37) for sponsoring this work. G. J. Kabo and A. A. Kozyro are grateful
to the International SOROS Science Education Program for the SOROS Professor
Grant (Agreement No. 9/P-95) and for the SOROS Docent Grant (Agreement No.
9/D-95), respectively.

Thermodynamic properties of trans-2-cyclohexylcyclohexanol
699
REFERENCES
1. Upadyasheva, A. W.; Zelmenova, Z. I.; Ustyukoba, L. I. Proizvodstvo Organicheskih Produktov, 1983,
66–72.
2. Proizvodstvo Kaprolactama. Ovchinnikov, V. I.; Rychinsky, V. R.: editors. Khimiya: Moscow. 1977.
3. Chalmers, L. Domestic and Industrial Chemical Specialities. Leonard Hill: London. 1966.
4. O’Rourke, D. F.; Mraw, S. C. J. Chem. Thermodynamics, 1983, 15, 489–502.
5. Adachi, K.; Suga, H.; Seki, S. Bull. Chem. Soc. Japan, 1968, 45, 1073–1087.
6. Horn, A.; Klaeboe, P.; Myrvold, B. O. Spectrochim. Acta, 1986, 42A, 1141–1154.
7. Kennet, H.; Kelly, K.; Mattens J. J. Chem. Eng. Data, 1969, 14, 276–277.
8. Sevruk, V. M.; Simirsky, V. V.; Kabo, G. J. Zh. Fiz. Khim. 1990, 64, 3402–3404.
9. Krasulin, A. P.; Kozyro, A. A.; Kabo, G. J. Zh. Prykl. Khim. 1987, 60, 104–108.
10. Krasulin, A. P.; Kozyro, A. A. Vestnik Beloruss. Gos. Universiteta Ser. 2 1987, 3, 20–23.
11. de Wit, H. G. M.; van Miltenburg, J. C.; de Kruif, C. G. J. Chem. Thermodynamics 1983, 15, 651–663.
12. de Kruif, C. G.; Blok, J. G. J. Chem. Thermodynamics 1982, 14, 201–206.
13. Frenkel, M. L.; Kaler, G. V.; Simirsky, V. V. Zh. Fiz. Khim. 1989, 63, 2277–2279.
14. Rossini, F. D. Experimental Thermochemistry, Vol. 1, Chap. 4. Rossini, F. D.: editor. Interscience:
New York, London. 1956.
15. Aleksandrov, Yu. J.; Oleynik, B. N.; Usvyatseva, T. R. Trudy Metrolog. Inst. SSSR Izd. Standartov.
Moscow-Leningrad. 1971, 189, 155–177.
16. Pure Appl. Chem. 1976, 47, 75–95.
17. CODATA Key Values for Thermodynamics. Cox, J. D.; Wagman, D. D.; Medvedev, V. A.: editors.
Hemisphere: New York. 1989.
18. Marachuk, L. I.; Kozyro, A. A.; Simirsky, V. V. Zh. Prykl. Khim. 1992, 64, 875–880.
19. TRC Thermodynamic Tables. Hydrocarbons. Marsh, K. N.: Director. The Texas A & M University
System: College Station. 1993, m-tables.
20. Nakamura, N.; Suga, Y.; Seki, S., Bull. Chem. Soc. Japan 1980, 53, 2755–2761.
(Received 7 September 1996; in final form 1 February 1997)
WA049/96