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J. Chem. Eng. Data 2000, 45, 704-708
Low-Temperature Heat Capacities and Derived Thermodynamic Functions of Para-Substituted Halogen Benzenes. 1. p-Chlorobromobenzene and p-Chloroiodobenzene J. Cees van Miltenburg,* Harry A. J. Oonk, and Gerrit J. K. van den Berg Chemical Thermodynamics Group, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
Heat capacity measurements were made on p-chlorobromobenzene and p-chloroiodobenzene from 5 K to 360 K. The measurements were used to calculate the entropy and enthalpy relative to 0 K. The enthalpy of melting of p-chlorobromobenzene was found to be (18 696 ( 20) J‚mol-1 and the triplet point temperature (337.93 ( 0.01) Κ. For p-chloroiodobenzene these values were respectively (16 103 ( 20) J‚mol-1 and (326.72 ( 0.01) Κ. Α very small glass transition was found in p-chloroiodobenzene between 270 K and 283 K.
Introduction The para-substituted benzenes, with the substituting groups -Cl-, -Br-, and -I-, form an interesting family of compounds. The compounds have been used in binary systems to study thermodynamic aspects of mixing in the solid and liquid state. Examples of this work are to be found in the work of Campbell and Prodan1 and the thesis of van der Linde,2 which also contains thermodynamic data of the pure compounds p-dichlorobenzene and p-dibromobenzene. Correlations of the thermochemical and phase-diagram data for the binary systems were discussed by Calvet et al.3 The compounds that are the subject of this calorimetric study (p-chloroiodobenzene and p-chlorobromobenzene) have not been investigated with low-temperature calorimetry. Other data like DSC or microcalorimetry data are very scarce. The enthalpy of fusion of p-chlorobromobenzene has been measured;1,4 however, for p-chloroiodobenzene we did not find any data at all. Structural investigations of these compounds are more numerous.5,6 The two compounds give rise to just one crystalline form, which is the same for both. The space group is P21/a with two molecules per unit cell. The crystal structures show orientational disorder in that the positions of the two different halogens cannot be distinguished by X-ray diffraction.7,8 The issue of orientational disorder has recently been addressed again by Meriles et al.9 who applied nuclear quadrupole resonance. The purpose of this work is to obtain reliable thermodynamic data such as entropy and heat capacity values for the six possible para-substituted dihalobenzenes. Fluorinesubstituted benzenes were not taken into consideration, because it is very difficult to obtain these compounds. Experimental Section The two compounds were purchased from Aldrich, with a stated purity of 99%. Both compounds were vacuumsublimated before use. In this sublimation procedure, the first and last part (about 10%) of the sublimated compound were rejected. For most compounds, this method gives an improvement in purity. The calorimeter vessel was filled * Corresponding author. Fax: +31 302533946. E-mail: miltenb@ chem.uu.nl.
to the maximum, using 8.4 g for p-chlorobromobenzene and 9.88 g of p-chloroiodobenzene. After being filled, the vessel was evacuated and filled with about 1000 Pa of helium to improve heat conduction. The calorimeter used, laboratorydesignation CAL V, has been described before.10 More recent improvements in design and data handling were described in 1998 by van Miltenburg et al.11 Measurements were made in the intermittent mode. Stabilization periods from about 600 s to 1000 s were used between the heating periods. Below 30 K, the periods were on the order of 150 s. Below 30 K, the reproducibility of the calorimeter is about 1%, between 30 K and 100 K, 0.05-0.1%, and above 100 K, 0.03%. Checking the calorimeter with standard materials (n-heptane and synthetic sapphire) showed no deviations larger than 0.2% from the recommended values. Results and Discussion p-Chlorobromobenzene. The experimental data series are given in Table 1. First, the sample was melted (series 1) and then cooled in about 2 h to 80 K and in 1 more hour to 5 K. Series 2 and 3 give the measurements between 5 K and 30 K, and series 4-6 form a continuous set with increasing temperature. In between these series, measurements were stopped for about 12 h. No solid-solid-phase transitions were observed. The measured heat capacity curve is shown in Figure 1. There are a few points that deviate by more than that expected from the reproducibility of the measurements. Inspection of the files did not reveal any irregularity in the measurements. Melting Behavior. Assuming that a small concentration of impurity in the sample causes a eutectic melting behavior, the impurity can be calculated using the law of van’t Hoff for freezing point depression. The impurity is solvable in the liquid phase and the actual concentration in the liquid during the melting process becomes x/F in which x is the molar fraction of the impurity of the sample and F is the melted fraction. The van’t Hoff relation then becomes
T ) T* -
( )
RT*2 x F ∆liq solH
(1)
A plot of the equilibrium temperature of the melt versus
10.1021/je990311t CCC: $19.00 © 2000 American Chemical Society Published on Web 06/21/2000
Journal of Chemical and Engineering Data, Vol. 45, No. 4, 2000 705 Table 1. Experimental Data Series for p-Chlorobromobenzene T
Cp
K
J‚K-1‚mol-1
series 1 298.17 300.18 303.19 306.18 309.17 312.17 315.16 318.15 321.14 324.12 327.11 330.09 333.08 335.97 337.62 337.87 337.89 337.90 337.91 339.56 342.54 345.51 348.48 351.43 354.38 357.33 360.27 363.20 366.12 369.04 series 2 5.57 6.47 7.57 8.89 10.24 11.83 13.61
145.53 146.25 147.52 148.72 149.95 151.22 152.53 153.80 155.09 156.44 157.88 159.45 161.93 187.35 2302 39952 122338 158651 326294 182.99 183.79 184.41 185.04 185.74 186.42 187.08 187.82 188.56 189.15 189.88 0.63 1.02 1.68 2.83 4.26 6.24 8.51
T
Cp
T
Cp
T
Cp
K
J‚K-1‚mol-1
K
J‚K-1‚mol-1
K
J‚K-1‚mol-1
15.57 17.72 20.03 22.40 24.57 26.43 28.11 29.64 series 3 5.59 6.76 7.83 9.28 10.74 12.26 14.09 16.09 18.25 20.58 22.91 24.99 26.79 28.42 29.90 series 4 31.05 32.02 33.77 36.34 38.81 41.31 43.83 46.37 48.94 51.54 54.17 56.83 59.50 62.20
11.15 14.07 17.17 20.34 23.30 25.40 26.46 28.26
64.92 67.66 70.42 73.19 75.98 78.78 81.59 84.42 87.26 90.11 92.97 95.84 98.72 series 5 101.55 103.20 105.48 108.41 111.31 114.22 117.13 120.05 122.97 125.89 128.82 131.74 134.67 137.61 140.55 143.49 146.45 149.41 152.35 155.29 158.24 61.19 164.14 167.09 170.04
52.86 54.15 55.54 56.90 58.15 59.29 60.71 61.91 63.11 64.36 65.66 66.86 68.00
172.99 175.94 178.90 181.86 184.82 187.78 190.74 193.70 196.66 199.62 202.58 205.54 208.49 211.46 214.43 217.40 220.37 223.34 226.31 229.26 232.21 235.19 238.15 241.09 244.04 247.01 249.99 252.95 255.92 258.89 261.86 264.83 267.79 270.75 273.71 276.68 279.64 series 6 281.56
97.29 98.51 99.64 100.75 101.77 102.92 104.00 105.12 106.09 107.32 108.15 110.96 110.80 111.91 113.06 114.18 115.31 114.66 117.86 119.81 118.01 120.81 122.09 126.47 124.59 125.71 126.91 127.89 128.49 129.66 130.87 132.10 133.24 134.49 135.85 136.94 138.19
0.88 1.49 1.96 3.24 4.84 6.76 9.15 11.90 14.89 17.88 21.01 23.83 25.57 26.82 28.61 29.25 30.92 32.75 35.08 36.42 38.35 40.19 41.88 43.55 45.44 46.97 48.46 49.91 51.50
Figure 1. Experimental heat capacity data of p-chlorobromobenzene.
the reciprocal of the melted fraction (1/F) was used to calculate the purity and the triple-point temperature (T*). The results of the second melting experiment are given in Figure 2. From this curve, a mole fraction of impurity of 0.000 25 was calculated, corresponding to a purity of 99.97%. The triple-point temperature is (337.93 ( 0.01) K. The two melting experiments gave for the enthalpy of melting 18 691 J‚mol-1 and 18 701 J‚mol-1, respectively. No significant difference between the first and second melting experiment was found. The mean value of the enthalpy of fusion is (18 696 ( 20) J‚mol-1. This value corresponds well with the value reported by Cambell and Prodan1 of 18 761 J‚mol-1. They reported a melting temperature of 337.73 K. Adjusting this
69.82 70.23 71.07 72.29 73.37 74.50 75.71 76.80 77.92 79.21 80.42 81.56 82.67 83.79 84.86 86.23 84.92 88.28 89.53 90.63 91.79 92.85 93.93 95.08 96.17
T
Cp
K
J‚K-1‚mol-1
282.54 284.29 286.78 289.27 291.76 294.23 296.70 299.15 301.60 304.04 306.47 308.89 311.31 313.71 316.11 318.49 320.87 323.24 325.60 327.95 330.28 332.58 334.80 336.62 337.54 337.79 337.86 337.89 337.90 339.73 341.94 344.15 346.36 348.56 350.75 352.95 355.14 357.32
139.82 141.09 143.39 142.99 144.03 145.08 146.24 147.22 148.21 149.25 150.20 151.25 152.37 153.48 154.56 155.75 157.00 158.36 159.92 161.87 164.92 171.11 194.05 402.56 2179 8602 22965 60299 322975 183.37 183.85 184.42 184.90 185.35 185.82 186.37 186.91 187.38
139.06
Figure 2. Melting behavior of p-chlorobromobenzene. The equilibrium temperature in the melt is plotted versus the reciprocal of the melted fraction.
temperature for the changes in the international temperature scales12 gives a value of 337.77 K. The liquid heat capacity data of the two series can be represented by a linear function, Cp,l(T) ) {(106.71 ( 1.32) + (0.225 32 ( 0.0037)(T/K)} J‚K-1‚mol-1, and the standard error of this fit is 0.14 J‚K-1‚mol-1, corresponding to about 0.08%. The low-temperature data were fitted according to the Debye low-temperature limit for the heat capacity curve, Cp ) RT3. The value for R was determined to be 0.004 06 J‚K-4‚mol-1, using this value to calculate the starting values of S° and H(T) - H(0), Table 2 was calculated by numerical integration of the interpolated heat capacity and enthalpy data. In Table 2, the derived
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Journal of Chemical and Engineering Data, Vol. 45, No. 4, 2000
Table 2. Thermodynamic Properties at Selected Temperatures for p-Chlorobromobenzene T
C°p,m
∆S°m
∆H°m
Φ°m
T
C°p,m
∆S°m
∆H°m
Φ°m
K
J‚K-1.mol-1
J‚K-1.mol-1
J‚mol-1
J‚K-1.mol-1
K
J‚K-1.mol-1
J‚K-1.mol-1
J‚mol-1
J‚K-1.mol-1
10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200
4.01 17.14 28.71 37.34 44.32 50.19 55.33 59.9 64.31 68.82 72.88 76.78 80.89 84.66 88.53 92.42 96.16 100.05 103.73 107.45
1.35 8.07 17.37 26.94 36.04 44.67 52.8 60.5 67.81 74.81 81.57 88.08 94.39 100.52 106.5 112.34 118.06 123.66 129.17 134.58
10 114 348 683 1092 1566 2094 2671 3292 3957 4667 5415 6203 7031 7898 8803 9746 10727 11746 12802
0.34 2.34 5.77 9.87 14.20 18.57 22.88 27.11 31.23 35.24 39.15 42.95 46.67 50.30 53.85 57.32 60.73 64.07 67.35 70.58
210 220 230 240 250 260 270 280 290 298.15 300 310 320 330 337.92a 337.92b 340 350 360 370
111.36 115.17 119.08 122.88 126.91 130.11 134.16 138.34 143.29 146.82 147.56 151.83 156.09 160.36 163.73 182.85 183.32 185.57 187.83 190.08
139.92 145.18 150.39 155.54 160.64 165.67 170.66 175.61 180.58 184.60 185.51 190.42 195.30 200.17 204.01 259.39 260.52 265.86 271.12 276.30
13895 15027 16200 17408 18657 19941 21263 22626 24040 25222 25494 26991 28531 30113 31396 50110 50490 52335 54202 56092
73.75 76.88 79.96 83.00 86.01 88.97 91.91 94.81 97.68 100.00 100.53 103.35 106.15 108.92 111.11 111.11 112.02 116.34 120.56 124.70
a
Solid. b Liquid phase.
Table 3. Experimental Data Series for p-Chloroiodobenzene T
Cp
T
Cp
T
Cp
T
Cp
T
Cp
K
J‚K-1‚mol-1
K
J‚K-1‚mol-1
K
J‚K-1‚mol-1
K
J‚K-1‚mol-1
K
J‚K-1‚mol-1
series 1 111.30 113.04 115.37 118.30 121.22 124.14 127.06 129.98 132.91 135.84 138.78 141.71 144.65 147.59 150.53 153.47 156.42 159.36 162.30 165.24 168.19 171.13 174.08 177.04 179.98 182.93 185.88 188.83 191.78 194.73 197.69 200.64 203.59 206.54 209.50 212.44 215.39 218.34 221.28 224.23 227.17 230.12 233.07 236.04 239.00 241.96
76.31 76.95 77.81 78.89 80.00 81.07 82.38 83.47 84.51 85.62 86.70 87.76 88.84 89.93 91.08 92.27 93.30 94.37 95.41 96.57 97.54 98.63 99.71 100.86 101.98 103.01 104.08 105.15 106.23 107.29 108.35 109.53 110.58 111.71 112.75 113.95 115.00 116.03 117.21 118.36 119.56 120.61 121.43 122.90 124.01 125.15
244.93 247.90 250.87 253.84 256.82 259.80 262.78 265.75 268.71 271.66 274.62 277.30 series 2 297.28 299.37 302.38 305.35 308.32 311.28 314.24 317.20 320.13 322.87 324.82 325.73 326.08 326.24 326.33 326.39 327.42 329.83 332.95 335.99 338.96 341.92 344.89 347.86 350.82 353.79 356.76 359.72 362.68 365.64 368.61 series 3 5.86 7.28
8.50 9.82 11.28 12.82 14.48 16.28 18.19 20.18 22.25 24.37 26.54 28.79 31.10 series 4 6.83 8.89 10.17 11.57 13.27 15.05 16.92 18.90 20.96 23.07 25.22 27.42 29.70 32.02 series 5 33.57 34.69 36.54 39.11 41.61 44.10 46.63 49.19 51.78 54.39 57.03 59.70 62.39 65.10 67.83 70.58 73.34 76.13
4.20 5.89 7.96 10.34 12.81 15.50 18.16 20.82 23.68 26.59 28.92 30.80 33.28
78.92 81.73 84.55 87.39 90.24 93.09 95.95 98.82 series 6 101.34 103.00 105.77 109.63 113.46 117.29 121.13 124.98 128.85 132.72 136.59 140.47 144.35 148.24 152.13 156.04 159.93 163.84 167.75 171.66 175.58 179.51 183.43 187.35 191.28 195.21 199.14 203.05 206.93 210.78 214.60 218.40 222.17 225.91 229.62 233.31 236.98 240.63
62.47 63.89 65.10 66.26 67.49 68.74 69.93 71.03
244.25 247.85 251.43 254.99 258.54 262.07 265.57 269.05 272.50 275.92 279.32 282.70 286.07 289.41 292.74 296.06 299.35 series 7 296.38 297.49 299.55 302.53 305.51 308.49 311.45 314.42 317.38 320.32 323.06 324.97 326.60 326.63 327.65 330.22 333.35 336.41 339.40 342.38 345.36 348.35 351.33 354.32 357.31 360.30
126.36 127.45 128.62 129.32 130.15 131.41 132.63 134.05 135.48 137.06 138.58 138.32 147.75 148.91 150.14 151.47 152.80 154.20 155.53 157.30 164.67 220.57 688 2493 6499 12505 18082 29339 562 185.43 185.99 186.59 187.40 188.13 188.59 189.05 189.64 190.33 190.91 191.61 192.21 192.91 193.45 1.62 3.03
2.38 4.68 6.42 8.53 11.03 13.63 16.38 19.20 21.90 24.87 27.65 29.47 31.87 34.33 36.08 37.12 38.47 39.86 41.78 43.54 45.29 46.84 48.73 50.20 51.80 53.21 54.79 56.12 57.39 58.79 60.13 61.36
72.69 73.08 74.13 75.60 77.03 78.49 79.94 81.42 83.02 84.43 85.88 87.31 88.75 90.43 91.67 92.76 93.73 95.97 97.36 98.80 100.35 101.83 103.28 104.69 106.19 107.56 108.98 110.45 111.93 113.29 114.73 116.15 117.55 118.96 120.46 121.88 123.27 124.66
126.05 127.42 128.81 129.48 130.83 132.32 133.84 135.50 137.35 138.99 140.74 142.38 144.03 145.34 146.74 148.06 149.11 148.47 149.10 149.79 151.00 152.52 153.91 155.26 156.48 158.19 165.99 223.26 754 46405 50215 431 185.53 186.23 186.89 187.60 188.19 188.83 189.32 190.12 190.57 191.31 192.07
Journal of Chemical and Engineering Data, Vol. 45, No. 4, 2000 707 Table 4. Thermodynamic Properties at Selected Temperatures for p-Chloroiodobenzene def
(M ) 238.45 g·mol-1, Φ°m ) ∆Τ0 S°m - ∆Τ0 H°m/T)
Figure 3. Experimental heat capacities of p-chloroiodobenzene.
Figure 4. Heat capacity values (b) and drift (2) for p-chloroiodobenzene around the solid glass transition. The drift (see text) is plotted on the right axis.
T
C°p,m
∆S°m
∆H°m
Φ°m
K
J‚K-1.mol-1
J‚K-1.mol-1
J‚mol-1
J‚K-1.mol-1
10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 298.15 300 310 320 326.71a 326.71b 330 340 350
6.15 20.57 32.18 40.53 47.43 53.38 58.50 63.01 67.39 71.80 75.74 79.51 83.44 87.13 91.03 93.75 98.19 102.02 105.71 109.30 113.00 116.75 120.61 124.42 128.26 131.45 136.00 141.07 145.59 149.15 150.00 154.60 159.26 162.39 184.80 185.51 187.64 189.77
2.41 11.20 21.94 32.50 42.31 51.51 60.14 68.25 75.93 83.26 90.29 97.04 103.56 109.88 116.02 121.99 127.82 133.54 139.16 144.67 150.09 155.44 160.71 165.92 171.08 176.17 181.21 186.25 191.28 195.37 196.29 201.28 206.23 209.55 258.82 260.67 266.24 271.71
17 152 421 790 1 232 1 737 2 297 2 906 3 558 4 253 4 992 5 768 6 583 7 436 8 326 9 251 10 213 11 214 12 253 13 327 14 439 15 588 16 775 18 000 19 263 20 560 21 896 23 282 24 716 25 917 26 194 27 716 29 285 30 364 46 461 47 071 48 936 50 823
0.65 3.56 7.89 12.74 17.68 22.56 27.32 31.93 36.40 40.72 44.91 48.98 52.93 56.77 60.52 64.17 67.75 71.24 74.67 78.03 81.34 84.58 87.78 90.93 94.03 97.09 100.11 103.10 106.05 108.44 108.98 111.87 114.72 116.61 116.61 118.04 122.31 126.50
a
Figure 5. Melting behavior of p-chloroiodobenzene. The equilibrium temperature in the melt versus the reciprocal of the melted fraction is given.
thermodynamic properties S(T), H(T) - H(0), and -{H(T) - H(0) - T.S}/T are given. p-Chloroiodobenzene. The method of measurement and the thermal history of this compound are identical to the description for p-chlorobromobenzene. The experimental data are given in Table 3 and are plotted in Figure 3. In Figure 4 the heat capacity data between 160 K and 300 K are shown, together with the observed temperature drift multiplied by the total heat capacity of the vessel and its contents in the stabilization periods. The latter value is called drift and is plotted in microwatts. The combination of these curves gives a strong indication that a small glass transition in the solid phase took place. When approaching the glass transition, the drift increases because of relaxation of the glass. Both at and after the glass transition, the drift decreases when the relaxed energy is recovered. A glass transition in the solid is not uncommon in the 1,4disubstituted benzenes and the chloro-, bromo-, and iodotoluenes all show this behavior.13 For p-chloroiodobenzene, the transition takes place between 270 K and 283 K; we estimate the heat capacity jump to be 2.8 J‚K-1‚mol-1
Solid. b Liquid phase.
Melting Behavior. Two melting experiments were performed. The second experiment was used to calculate the purity. The plot of the equilibrium temperature versus the reciprocal of the melted fraction is shown in Figure 5. The calculated purity is 99.83% and the triple-point temperature is (326.72 ( 0.01) K. The enthalpies of fusion measured were 16 109 J‚mol-1 and 16 097 J‚mol-1. The average value is (16 103 ( 20) J‚mol-1. The derived thermodynamic data are given in Table 4. A fit of the data below 12 K gave the value for R ) 0.0081 J‚K-4‚mol-1. Heat Capacity of the Liquid. The heat capacity data of two series in the liquid phase (25 data points) were fitted to a linear function,
Cp,l(T) ) {(116.95 ( 0.78) + (0.2077 ( 0.0022)(T/K) } J‚K-1‚mol-1 (2) The standard error of this fit is 0.12 J‚K-1‚mol-1, corresponding to 0.06% of the absolute value. Literature Cited (1) Campbell, A. N.; Prodan, L. A. An Apparatus for Refined Thermal Analysis Exemplified by a Study of the System p-Dichlorobenzene-p-Dibromobenzene-p-Chlorobromobenzene. J. Am. Chem. Soc. 1948, 70, 553-561.
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Journal of Chemical and Engineering Data, Vol. 45, No. 4, 2000
(2) van der Linde, P. R. Molecular Mixed Crystals from a Thermodynamic Point of View. Ph.D. Thesis, Utrecht University, Utrecht, The Netherlands, 1992. (3) Calvet, M. T.; Cuevas-Diarte, M. A.; Haget, Y.; van der Linde, P. R.; Oonk, H. A. J. Binary p-Dihalobenzene SystemssCorrelation of Thermochemical and Phase-Diagram Data. Calphad 1991, 15, 225-234. (4) Narbutt, J. Die Spezifischen Warmen und Schmeltzwarmen der Dichloro-, Chlorbrom-, Dibrom-, Bromjod-, und Dijodbenzole. Z. Electrochem. 1918, 339-342. (5) Meriles, C. A.; de Almeide Santos, R. H.; do Prado Gambardella, M. T.; Ellena, J.; Mascarenhas Y. P.; Brunetti, A. H. Crystal Structures of p-Chlorobromobenzene and p-Chloroiodobenzene J. Mol. Struct. 1999, 513, 245-250. (6) Calvet, T.; Cuevas-Diarte, M. A.; Tauler, E.; Labrador, M.; Haget, Y.; Oonk, H. A. J. Molecular Alloys in the Series of ParaDisubstituted Benzene Derivates. Part VII. J. Chim. Phys. 1995, 92, 2038-2047. (7) Klug, A. Crystal Structure of p-Bromochlorobenzene. Nature 1947, 160, 570. (8) Britton, D. The Crystal Structure of p-Chloroiodobenzene. Acta Crystallogr. 1976, B32 (3), 976. (9) Meriles, C. A.; Pe´rez, S. C.; Wolfenson A. E.; Brunetti, A. H. ShortRange Orientational Correlation in the Disordered Crystal of 1-Chloro-4-iodobenzene. J. Chem. Phys. 1999, 110, 7392-7402.
(10) Van Miltenburg, J. C.; van den Berg, G. J. K.; van Bommel, M. J. Construction of an Adiabatic Calorimeter. Measurements of the Molar Heat Capacity of Synthetic Sapphire and of n-Heptane. J. Chem. Thermodyn. 1987, 19, 1129-1137. (11) Van Miltenburg, J. C.; van Genderen, A. C. G.; van den Berg, G. J. K. Design Improvements in Adiabatic Calorimetry. The Heat Capacity of Cholesterol between 10 and 425 K. Thermochim. Acta 1998, 319, 151-162. (12) Goldberg, R. N.; Weir, R. D. Conversion of Temperatures and Thermodynamic Properties to the Basis of the International Temperature Scale of 1990. Pure Appl. Chem. 1992, 10, 15451562. (13) Van Miltenburg, J, C.; Alvarez-Larena, A.; Labrador, M.; Palacios, L.; Rodriquez-Romero, J.; Tauler, E.; Estop, E. The Thermal Properties of Three (Cl-, Br-, I-) Para-Halotoluenes. Formation of Glassy Crystals. Thermochim. Acta 1996, 273, 31-42.
Received for review December 8, 1999. Accepted April 28, 2000.
JE990311T
