694
J. Chem. Eng. Data 2008, 53, 694–703
Thermodynamics of Cyclohexanone Oxime Dzmitry H. Zaitsau, Yauheni U. Paulechka, Gennady J. Kabo,* and Andrey V. Blokhin Chemistry Faculty, Belarusian State University, Leningradskaya 14, 220030 Minsk, Belarus
Vladimir N. Emel’yanenko, Sergey P. Verevkin, and Andreas Heintz Department of Physical Chemistry, University of Rostock, Hermannstr. 14, 18051 Rostock, Germany
The heat capacity of cyclohexanone oxime in the interval of (5 to 370) K was measured in an adiabatic calorimeter. The triple-point temperature Tfus ) (362.20 ( 0.04) K and the enthalpy of fusion ∆crliqHm° ) (12454 ( 20) J · mol-1 were determined. The vapor pressure was measured by the Knudsen method over crystalline cyclohexanone oxime in the interval of (288 to 323) K and by the transpiration method over crystalline, T ) (286 to 348) K, and liquid, T ) (365 to 395) K, cyclohexanone oxime. Thermodynamic properties in the ideal-gas state were calculated based on the experimental molecular and spectral data and the results of DFT (B3LYP/6-311G(d)) calculations. The experimental and calculated values of the entropy of gaseous cyclohexanone oxime agree within 1 % in the interval of (310 to 362.2) K.
Introduction
Experimental
Cyclohexanone oxime (C6H11NO), which will be referred by the acronym (CHO) throughout the paper, is an intermediate in the caprolactam synthesis. In industry, isomerization of CHO is carried out with the use of oleum. This gives rise to technical and ecological problems related with utilization of sulfuric acid or its derivatives remaining after caprolactam separation. Nowadays, alternative schemes of the synthesis are being developed, e.g., with the use of ionic liquids.1
Sample. The commercial sample of CHO (Grodno Azot) with the initial mass fraction purity of 0.95 (water was the main impurity) was sublimed at T ) 338 K and p ) 0.3 kPa. Additionally, it was dried over P2O5 for 2 weeks. The mass fraction of CHO in the sample was found to be 0.9997 ( 0.0003 with a CHROM-5 chromatograph equipped with a katharometer as a detector. A column (Polysorb stationary phase) of 1 m length and 3 mm diameter was used. The temperature of the column during analysis was T ) 473 K. From the fractional melting experiments in an adiabatic calorimeter, the mole fraction purity of the sample was 0.9998 ( 0.0001. This sample was used in the calorimetric and effusion experiments. For the transpiration experiments, the commercially available CHO (Merck, mass fraction 0.98) was freshly sublimed prior to experiment. The degree of purity was determined using a Hewlett-Packard gas chromatograph 5890 Series II equipped with a flame ionization detector and a Hewlett-Packard 3390A integrator. A capillary column HP-5 (stationary phase crosslinked 5 % PH ME silicone) was used with a column length of 30 m, an inside diameter of 0.32 mm, and a film thickness of 0.25 µm. The standard temperature program of the GC was T ) 353 K for 60 s followed by a heating rate of 10 K · min-1 to T ) 523 K. No impurities (mass fraction greater than 0.0002) could be detected in the sample used for the transpiration measurements. Adiabatic Calorimetry. The heat capacity of CHO under saturated vapor pressure (Cs) in the interval of (5 to 370) K and the fusion enthalpy were determined in a Termis TAU - 10 adiabatic calorimeter. The apparatus and experimental procedures were described elsewhere.5 The sample was loaded in the calorimetric container in a drybox. The uncertainty of the heat capacity measurements was ( 0.4 % in the interval of (20 to 370) K and 1 % in the range of (10 to 20) K and did not exceed 2 % below 10 K.5 Spectrometry. The IR spectra for CHO in a CCl4 solution and in KBr pellets were recorded with a Bruker Vertex 70
The thermodynamic properties for CHO in the condensed and gaseous states were reported earlier.2 It was noted that the difference in the sublimation enthalpies obtained from the Knudsen method and by calorimetry was 2.5 kJ · mol-1 which is double the value of the combined uncertainty of both the methods. Afterward,3 it was shown that the isotropy failure of a gas in an effusion cell should be taken into account to obtain the reliable vapor pressure and the vaporization enthalpy from the Knudsen experiments. The heat capacity values from ref 2 also do not seem to be reliable enough. For example, the heat capacity for CHO2 was 1.5 J · K-1 · mol-1 at 5 K. This value is much higher than the heat capacity of crystalline caprolactam at the same temperature.4 There was a peak in the heat capacity curve at T ) 273 K probably caused by the presence of water in the sample.2 The above-mentioned reasoning together with the development of the new computational methods has brought us to a conclusion that a new comprehensive study of thermodynamic properties for CHO was necessary. The results of the study are reported in this work, and they include heat capacity and parameters of phase transitions from adiabatic calorimetry, vapor pressures over crystalline and liquid CHO, and thermodynamic properties of CHO in the ideal-gas state obtained from the statistical thermodynamic and quantum chemical calculations. * To whom correspondence should be addressed. Tel./fax: +375-172203916. E-mail:
[email protected].
10.1021/je700546r CCC: $40.75 2008 American Chemical Society Published on Web 02/16/2008
Journal of Chemical & Engineering Data, Vol. 53, No. 3, 2008 695 Table 1. Experimental Heat Capacities for CHO (M ) 0.113159 kg · mol-1) T
Csa
T
Csa
T
Csa
T
Csa
K
J · K-1 · mol-1
K
J · K-1 · mol-1
K
J · K-1 · mol-1
K
J · K-1 · mol-1
214.38 216.30 218.21 220.14 222.06 224.01 225.92 227.85 229.78 231.71 233.64 235.57 237.50 239.43 241.36 243.30 245.25 247.18
126.63 128.63 130.69 132.72 134.69 136.62 138.42 140.09 141.60 143.03 144.32 145.51 146.68 148.81 153.60 148.43 149.53 150.98
310.43 312.22 314.11 316.00 317.89 319.77
193.00 193.77 194.56 195.45 196.42 197.45
121.72 123.73 125.75 127.76 129.79 131.81 133.83 135.86 137.88 139.90 141.92 143.95 145.97 148.00 150.03 152.05 154.08 156.10 158.12 160.13 162.15 164.16 166.17 168.18 170.18 172.19 174.19 176.19 178.20 180.20 182.19 184.18 186.16 188.14 190.12 192.10 194.08 196.05 198.02 199.97 202.00 203.92 205.74 207.56 209.36 211.17 212.97 214.76 216.54 218.32 220.09
75.080 75.978 76.855 77.722 78.601 79.494 80.384 81.282 82.162 83.046 83.955 84.852 85.734 86.671 87.591 88.519 89.422 90.343 91.274 92.237 93.182 94.145 95.080 96.066 97.045 98.050 99.046 100.08 101.13 102.17 103.23 104.31 105.44 106.57 107.71 108.92 110.15 111.36 112.60 113.87 115.31 116.79 118.31 119.91 121.66 123.38 125.27 127.11 128.94 130.87 132.70
Series 1 Crystal 79.94 81.67 83.39 85.10 86.83 88.55 90.28 92.01 93.75 95.49 97.23 98.97 100.72 102.52 104.37 106.23 108.09 109.95 111.81 113.68 115.55 117.41 119.29 121.16 123.03 124.91 126.79 128.67 130.55 132.43 134.31 136.20 138.09 139.98 141.87 143.76 145.65 147.54 149.44 151.34 153.24 155.13 157.03 158.93 160.83 162.73 164.63 166.54 168.44 170.35 172.26 174.17 176.08 177.99 179.90 181.81 183.72 185.64 187.55 189.46 191.37 193.29 195.20 197.13 199.05 200.97 202.89 204.81 206.72 208.63 210.55 212.46
56.264 57.037 57.845 58.585 59.395 60.203 61.007 61.805 62.621 63.419 64.210 65.031 65.829 66.597 67.436 68.291 69.080 69.916 70.758 71.569 72.371 73.203 74.027 74.846 75.633 76.462 77.293 78.113 78.910 79.754 80.585 81.418 82.254 83.084 83.927 84.770 85.617 86.492 87.350 88.171 89.045 89.889 90.765 91.646 92.535 93.455 94.346 95.254 96.201 97.126 98.073 99.058 100.02 101.03 102.04 103.07 104.11 105.14 106.25 107.37 108.48 109.62 110.84 112.05 113.28 114.62 116.00 117.51 119.13 120.93 122.71 124.68
Series 2 Crystal 217.00 218.98 220.87 222.75 224.62 226.48 228.33 230.18 232.03 233.87 235.71 237.54 237.54 239.36 241.18 242.99 244.82 246.66 248.48 250.29 252.11 253.91 255.71 257.50 259.28 261.05 262.82 264.58 266.34 268.08 269.82 271.56 273.28 275.02 276.74 278.45 280.15 281.85 283.54 285.24 286.93 288.61 290.29 291.97 293.65 295.32 297.00 298.66 300.33 301.99 303.67 305.36 307.05 308.74
129.41 131.50 133.52 135.43 137.24 138.92 140.45 141.86 143.15 144.33 145.65 146.94 146.94 148.90 153.75 148.41 149.34 150.69 152.19 153.82 155.49 157.22 159.00 160.82 162.64 164.53 166.41 168.33 170.21 172.13 174.08 175.95 177.73 179.53 181.37 183.01 184.62 186.12 187.50 188.79 189.90 190.97 191.83 192.78 193.64 194.51 195.34 196.34 197.85 196.75 191.89 191.49 191.78 192.41
Series 3 Crystal 305.83 307.60 309.38 311.16 312.94 314.72 316.49 318.27 320.04 321.81 323.58 325.35 327.11 328.87 330.63 332.40 334.15 335.91 337.67 339.42 341.17 342.93 344.68 346.43 348.18 349.93 351.67 353.42 355.16
191.51 191.89 192.47 193.22 194.04 194.70 195.61 196.48 197.43 198.43 199.58 200.52 201.48 202.64 203.71 204.63 205.60 206.77 207.80 208.77 209.83 210.86 212.10 213.18 214.14 215.30 216.38 217.49 218.64 Melt
356.90 358.64 360.36 361.67
220.12 222.02 229.30 646.2 Liquid
364.59 366.16 367.73
273.00 273.91 274.96 Series 4 Liquid
363.80 365.34 366.88 368.42
272.42 273.22 274.16 275.12 Series 5 Crystal
82.20 84.24 86.15 88.07 90.00 91.95 93.89 95.85 97.81 99.77 101.74 103.72 105.70 107.69 109.68 111.68 113.68 115.69 117.70 119.71
57.238 58.198 59.049 59.960 60.852 61.754 62.671 63.556 64.447 65.369 66.248 67.142 68.037 68.921 69.811 70.687 71.558 72.449 73.346 74.215
Series 6 Crystal 217.73 219.50 221.26 223.02 224.76 226.50 228.24 229.98 231.71 233.43 235.14 236.85 238.56 239.79 241.48 243.42 245.37 247.07 248.78 250.48 252.36
130.26 132.12 133.99 135.78 137.52 139.12 140.60 141.91 143.15 144.26 145.41 146.62 147.84 150.04 154.07 148.52 149.83 151.16 152.63 154.01 155.81
696 Journal of Chemical & Engineering Data, Vol. 53, No. 3, 2008 Table 1 Continued
a
T
Csa
T
Csa
T
Csa
T
Csa
K
J · K-1 · mol-1
K
J · K-1 · mol-1
K
J · K-1 · mol-1
K
J · K-1 · mol-1
254.12 255.80 257.47 259.14 260.80 262.46 264.11 265.75 267.39 269.02 270.64 272.26 273.87 275.47 277.08 278.67 280.26 281.85 283.43 285.01 286.58 288.15 289.72 291.28 292.85 294.41 295.97 297.53 299.09 300.64 302.19 303.76 305.34 306.91 308.49 310.07 311.68 313.36 315.03 316.71 318.38 320.11 321.98 323.80 325.62 327.43 329.24
157.42 159.11 160.79 162.49 164.29 166.09 167.84 169.58 171.43 173.27 175.04 176.79 178.52 180.26 181.92 183.43 185.03 186.38 187.69 188.93 189.97 191.00 191.92 192.69 193.59 194.19 194.99 195.76 196.66 198.30 195.88 191.84 191.58 191.81 192.20 192.72 193.28 194.05 194.86 195.66 196.46 197.40 198.37 199.44 200.47 201.55 202.56
331.06 332.88 334.70 336.52 338.35 340.17 341.99 343.81 345.63 347.45 349.27 351.09 352.91 354.73 356.54 358.35
203.58 204.71 205.74 206.77 207.86 209.00 210.15 211.29 212.36 213.43 214.58 215.74 217.26 219.00 221.91 227.53
334.74 336.49 338.25 339.99 341.74 343.49 345.25 346.99 348.74 350.48
14.03 14.64 15.26 15.98 16.81 17.65 18.49 19.34 20.19 21.32 22.74 24.16 25.59 27.02 28.49 30.12 31.73 33.50 35.28 37.06 38.84 40.63 42.51 44.49 46.48 48.47 50.46 52.45 54.45 56.45 58.46 60.47 62.48 64.50 66.51 68.52 70.54 72.56 74.59 76.61 78.65 80.68 82.71 84.75
6.5715 7.1526 7.7959 8.6012 9.4967 10.365 11.280 12.181 13.084 14.349 15.894 17.456 18.999 20.499 21.997 23.630 25.216 26.876 28.484 30.012 31.474 32.894 34.381 35.899 37.344 38.758 40.107 41.416 42.643 43.840 45.024 46.162 47.276 48.369 49.443 50.507 51.546 52.586 53.590 54.603 55.597 56.576 57.543 58.471
Melt 352.41 354.55 356.67 358.75 360.64 361.76
Liquid 367.52 368.96
274.57 275.31
364.48 365.92 367.36 368.79
Series 7 Crystal 292.14 293.70 295.26 296.81 298.36 299.91 301.45 303.01 304.57 306.14 307.71 309.27 310.95 312.72 314.48 316.25 318.01 319.77 321.54 323.30 325.05 326.81 328.56 330.32 331.23 332.98
205.77 206.75 207.78 208.85 209.95 210.94 212.02 213.12 214.13 215.24
192.79 193.66 194.41 195.24 196.04 197.34 198.75 192.59 191.66 191.69 191.96 192.53 193.22 193.93 194.70 195.55 196.38 197.36 198.27 199.26 200.28 201.27 202.22 203.27 203.73 204.75
4.900 5.136 5.378 5.624 5.878 6.165 6.485 6.812 7.147 7.488 7.836 8.187 8.542 8.902 9.268 9.636 10.00 10.48 11.06 11.64 12.23 12.83 13.43
216.96 219.52 222.61 231.68 314.35 1583.1 Liquid 272.66 273.48 274.33 275.25 Series 8 Crystal 0.33898 0.39671 0.46488 0.54188 0.62777 0.73332 0.86213 1.0064 1.1673 1.3381 1.5301 1.7352 1.9562 2.1896 2.4377 2.7078 2.9809 3.3609 3.8301 4.3255 4.8537 5.4079 5.9918
Average heat capacity at the mean temperature of an experiment.
spectrometer in a wavenumber range of (4000 to 400) cm-1 with resolution of 2 cm-1. Knudsen Method. The vapor pressure (psat) for CHO in the interval of (291 to 323) K was measured by the integral Knudsen method. The apparatus and the experimental technique were described elsewhere.3 The combined uncertainty of the measurements was established to be ( 5 %. Three nickel membranes were used in the effusion experiments: membrane 1 with thickness l ) (50 ( 1) µm and diameter d ) (0.1833 ( 0.0004) mm, membrane 2 with l ) (84 ( 1) µm and d ) (0.4467 ( 0.0005) mm, and membrane 3 with l ) (50 ( 1) µm and d ) (0.8370 ( 0.0005) mm. The vapor pressures were calculated according to the equation4
psat )
(
)
1 ∆m 1 + RγSsamp kWSorif τ
2πRT M
(1)
where psat is the vapor pressure for CHO; ∆m is the mass loss during the vacuum exposure time τ; Sorif is the cross sectional
area of the orifice; T is the temperature of the heat carrier in the thermostat where the copper block with an effusion cell is placed; M is the vapor molar mass (M ) 113.16 g · mol-1 was assumed);6 Ssamp is the exposed sample surface; R ) 8.31447 J · K-1 · mol-1; and Rγ is the product of the condensation coefficient (Langmuir) and the roughness coefficient for the sample surface. The kW transmission coefficient was determined according to Wahlbeck’s theory of isotropy failure of a gas in the Knudsen cell.7 The calculation technique was described earlier.3 The effective diameter for the CHO molecule (σ ) 0.578 nm) was calculated from its excluded volume8 assuming the molecule to be spherical. The excluded volume was calculated in the Tinker 4.0 package8 using the molecular geometry obtained in the quantum chemical calculations and the van der Vaals radii from ref 9. The kW coefficient depends on the vapor pressure in the effusion cell and the Knudsen number. The vapor pressure in the effusion cell can deviate from the equilibrium value due to
Journal of Chemical & Engineering Data, Vol. 53, No. 3, 2008 697 Table 3. Determination of the Molar Enthalpy of Fusion for CHO
a
Tstart
Tend
Q
liq 0 ∆cr Hm
K
K
J · mol-1
J · mol-1
354.41 350.75 349.77 350.41 348.93 average
363.44 365.41 364.46 364.23 363.06
14516 15851 15780 15607 15573
12461a 12464 12442a 12469 12436 (12454 ( 20)
From the fractional melting experiments.
Table 4. Thermodynamic Properties of CHO in the Condensed State ° Cp,m
T K
Figure 1. Temperature dependence of the heat capacity for cyclohexanone oxime. The broken curve shows the baseline used to calculate the thermodynamic properties for the anomalies. Table 2. Comparison of the Thermodynamic Properties Obtained in the Previous Study2 and This Work ° ∆T0 Sm (298.15K)
origin ref 2 this work
-1
J·K
-1
· mol
185.1 ( 0.5 185.8 ( 0.8
° ∆T0 Sm (g, 320 K)
° Cp,m (g, calc)
J · K-1 · mol-1
J · K-1 · mol-1
exptl
calcd
298 K
500 K
371.5 ( 1.0 373.5 ( 1.6
379.22 370.6
137.0 135.7
217.8 228.7
a high effusion flow through the orifice or Rγ
