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Heat Capacities and Thermodynamic Properties of 3-(2,2-Dichloroethenyl)-2,2-dimethylcyclopropanecarboxylic Acid
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CHEM. RES. CHINESE U. 2007, 2 3 ( 4 ) , 4 6 0 4 6 4 Article ID 1005-9040( 2007) 4 4 4 6 0 4 5
ScienceDirect
Heat Capacities and Thermodynamic Properties of 3 - ( 2 ,2-Dichloroethenyl) -2 ,2-dimethylcyclopropanecarboxylicAcid XUE Bin"*' , WANG Jian-ya' , TAN Zhi-cheng3 and WU Tong-hao' 1. School of Petrochemical Engineering, Shenyang University of Technology, Liaoyang 111003 , P. R. China ; 2. College of Chemistry, Jilin University, Changchun 130021, P . R. China ; 3. Themchemistry Laboratory, Dalian Institute of Chemical Physics, Chinese Academy of Science, Dalian 116023 , P . R. China Received Nov. 17, 2006 The heat capacities of 3-( 2,2-dichloroethenyl) -2,2-dimethylcyclopmpaecarboxylic acid ( a racemic mixture, molar ratio of cis-/trans-structure is 35/65) in a temperature range from 78 to 389 K were measured with a precise automatic adiabatic calorimeter. The sample was prepared with a purity of 98.75% ( molar fraction). A solid-liquid fusion phase transition was observed in the experimental temperature range. The melting point, T,,, , enthalpy and entropy of fusion, A,,H, , A,,S, , of the acid were determined to be ( 33 1.48 0.03 ) K , ( 16.321 0.03 1 ) kJ/mol,
*
*
and (49.24 *O. 19) J/( K * mol) , respectively. The thermodynamic functions of the sample, H, - H298, S, Sm8, and G, - G,, Is , were reported at a temperature intervals of 5 K. The thermal decomposition of the sample was studied using thermogravimetric(TG) analytic technique, the thermal decomposition starts at ca. 418 K and ends at ca. 544 K , the maximum decomposition rate was obtained at 510 K. The order of reaction, preexponential factor and activation energy are n = 0.23, A = 7 . 3 x lo7 min - I , E = 70.64 kJ/mol , respectively. Keywords 3-( 2,2-Dichlome.thenyl)-2,2-dimethylcyclopropanecarboxylicacid ; Adiabatic calorimetry ; Heat capacity ; Thermodynamic function ; Thermal decomposition
Introduction 3-( 2 , 2-Dichloroethenyl ) -2, 2-dimethylcyclopropanecarboxylic acid is one of the important intermediates for the preparation of fenpropathrin pesticide, and many kinds of high-performance and activity fenpropathrin pesticides such as permethrin , alphamethrin , cfluthrin , fenpyrithrin have been synthesized with this"-31. Its formula is C, H,, 0, Cl,, and its structure is shown in Scheme 1. OH
Scheme 1 Molecular structure of 3 4 2,2-dichloroethenyl)2,2-dimethylcyclopropaneearboxylicacid
There are four isomers of the acid, the two isomers, 1R-cis- and 1R-trans-3-( 2,2-dichloroethenyl) 2,2-dimethyIcyclopropanecarboxylicacids, can be used as the materials for the preparation of fenpropathrin pesticides, but the other two isomers, 1s-cis- and 1Strans-3-( 2 , 2-dichloroethenyl ) -2, 2-dirnethylcyclopropanecarboxylic acids are not used for the synthesis of fenpropathrin pesticides"-31 . The thermodynamic data is one of the important
*
bases for improving the synthesis process of fenpropathrin pesticide and studying the reaction mechanisms of synthesizing fenpropathrin pesticides , and calorimetry is one of the effectual methods for these r e ~ e a r c h e s ' ~ . ~ ] . Stereoselective synthesis and separation of the isomers of product and intermediates can reduce the used amount of insecticide, improve economic performance and decrease environmental pollution. In this work, the heat capacities of 3-( 2,2-dichloroethenyl ) -2 ,2-dimethylcyclopropanecarboxylic acid ( a racemic mixture , the molar ratio of cis-/trans-structure was 35/65) of high purity( 98.75% , molar fraction) were measured in a temperature range of 78-389 K with an automatic adiabatic calorimeter. At the same time, the melting point, T,,, , enthalpy and entropy of fusion, A,,H, , AfusS, , of the acid were calculated. The thermal decomposition of the sample was studied using thermogravimetric( TG) analytic technique.
Experimental 1 Sample Preparation and Analysis 3-( 2 , 2-Dichloroethenyl ) -2, 2-dimethylcyclopropanecarboxylic acid ( a racemic mixture, molar ratio of
Supported by the Education Bureau Science Foundation of Liaoning Province, China( No. 20040261 ) . To whom correspondence should be addressed. E-mail: xue-b@ 163. com
**
XUE
No.4
Bin et
al.
46 1
*
cis-/trans-structure is 35/65 ) was prepared by the hydrolysis of 3- (2,2-dichloroethenyl) -2 ,2-dimethylcyclopropanecarboxylic ester after the reaction of 1 ,1-dichloro4-me-thyl-l,3-~entadieneand diazoacidic ester"]. The crystal product of 3-( 2,2-dichloroethenyl) - 2 , 2 dimethylcyclopropanecarboxylic acid was filtered and recrystallized thrice. Finally, the sample was obtained. The molecular structure was verified using nuclear magnetic resonance( Bruker DRX4OO). The purity of the sample was determined to be 98.75% ( molar fraction) by high performance liquid chromatography( HPLC ) l6] (Shimazu 10A).
0 . 2 % compared with those"] of curacy was within the National Institute Science and Technology ( formerly the National Bureau of Standards, NBS ) in the whole temperature range. The heating rate was controlled in a range of 0 . 2 4 . 4 Wmin while the sample was in solid and li-quid phases. The interval of temperature rising was 2 4 K generally and the interval was reduced a little during sample melting. The duration of heating was mea-sured by means of a digitally displayed electronic timer-controller with an accuracy of s. The data were read and calculated automatically by a computer on the real time.
2 Adiabatic Calorimetry
3 TG Analysis
The heat capacity measurements were carried out Thermogravimetric analysis was performed with a with an automatic calorimeter over a temperature range TG 951 thermal balance in a temperature range of of 8 0 4 0 0 K. The equipment was based on the 340-550 K. A nitrogen gas flow rate of 150 m u m i n Nernst's step-heating method. The adiabatic calorimeand a heating rate of 3 Wmin were used. ter and the principle of the automatic adiabatic control Results and Discussion circuits have been de~cribed"'~] . 1 Heat Capacity To verify the reliability of the calorimeter, the moThe experimental molar heat capacities of 3-( 2 , 2 lar heat capacities of a-Al,O, were measured from 80 to dichloroethenyl) -2 , 2-dimethylcyclopropane carboxylic 400 K. The deviations of the experimental results from acid of a typical run are listed in Table 1 and shown in the smoothed curve are within 0. 1% , while the inacFig. 1. Table 1 Experimental molar heat capacities of 3-(2,2-dichloroethenyl) -2,2-dimethylcyclopropanecarboxylic acid
*
T/K 77.996 78.884 79.761 80.912 82.324 84.345 86.954 90.165 93.956 97.646 101.246 104.766 108.217 111.604 114.934 118.210 121.438 124.621 127.761 130.861 133.924 137.386 141.240 145.041
cF..rn
86.346 88.901 90.810 92.560 93.212 95.671 98.622 101.910 105.540 108.900 111.982 114.833 117.882 120.606 122.796 125.411 127.613 129.861 131.985 134. 116 136.248 138.797 141.318 144.010
T/K 148.792 152.498 156. 159 159.779 163.360 167.448 172.009 176.503 180.968 185.397 189.782 194.124 198.421 202.677 206.894 211.070 215.208 219.306 223.368 227.364 231.276 235. 180 239.044 242.817
CP*m
T/K
cP,m
146.632 149. 182 151.425 153.447 155.535 156.554 162.125 164.299 167.039 170.052 173.020 175.470 178.702 180.798 183.521 185.900 189.196 191.945 194.757 199.788 204. 139 207.885 210.664 215.015
246.610 250.4 14 254. 149 257.823 261.722 265.848 269.952 274.044 278.112 282. 156 286.176 290.165 294.114 298.020 301.875 305.669 309.397 313.227 316.945 320.085 322.690 324.969 326.852 328.296
218.882 222.021 223. 169 228.482 231.639 234.184 236.577 238.855 241.643 244.337 247. 129 250.585 256.141 260.938 270.263 280.754 293.781 315.789 382.31 1 494.825 598.628 696.532 987.054 1267.090
In the solid region, the heat capacities of the sample were measured for 60 points in a temperature range from 78 to 290 K and for eight points in the liquid re-
T/K
Cp.m
329.422 330.274 330.926 331.445 331.907 332.733 334.651 337.516 340.666 343.896 347.147 350.408 353.699 357.077 360.578 364.132 367.670 371.194 374.712 378.232 381.745 385.236 388.690
1712.696 2252.312 2780.153 3004.934 2436.495 1040.347 485.273 429.940 421.514 415.292 399.679 387.076 375.051 361.784 360.724 355.978 358.475 360.753 362.667 364.295 366.771 368.558 371.281
gion between 361 and 390 K. In fusion region, the heat capacities of the sample were determined for 27 points in temperature range from 290 to 360 K. NO
CHEM. RES. CHINESE U.
462
-g
3500 3000 2500-
e
.. $
%
20001500-
' .1000-
n-
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where, X = ( T - 184. 1)/106. 1 and T ( K ) is temperature. For liquid region( 361-390 K ) : CP,,=363.5381 + 6.57942X + 0.06604X2 + 1. 07814X3 (2) where, X = ( T - 376.4)/12.3 and T ( K ) is temperature. The deviation of the experimental data from the smoothed values in all the regions is within * O . 2 % .
c
500-
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I
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1
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Vol. 23
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100 150 200 250 300 350 TK
I 400
Fig. 1 Heat capacity curve of 3-( 2,2-dichloroethenyl)2,2-dimethylcycloproparbo~y~c acid
thermal anomaly was observed in solid and liquid regions, it shows that the structure of the compound is stable in the temperature range. The values of heat capacities were fitted with the following polynomial expressions using least squares method. For solid region( 78-290 K ) : Cp,m= 168.28729 + 72.12045X + 19. 1887X2 + 9. 3298X3 - 18. 331X4
(1)
2 Melting Point, Enthslpy and Entropy of Fusion, and Purity Determination To determine the melting point ( T , ) and molar enthalpy( AfusHm) , a step heating method was used. It is based on the following principle. The sample was heated with less heat once to measure the equilibrium temperature. The increment of the energy required to heat the sample from the temperature T, , below the melting point, to the temperature T, , above the melting point, was measured. With multiple heating, the melting point was approached and the enthalpy of fusion of the sample was derived from the following equation.
where n is the molar number of the sample; Q is the place from about 290 to 365 K . The determination of total amount of heat introduced into the sample; temperature of fusion T , and that of the enthalpy of fuCP,,,( S) , CP,,( L ) , and Ho are the heat capacity of sion A,,H, for the sample were carried out from three the sample in solid state, the sample in the liquid series of heat capacity measurements in this temperastate, and the empty cell, respectively. The entropy of ture range. The three runs of experimental and calcufusion Afu,S, of 3-( 2,2-dichloroethenyl) -2,2-dimethlated results are listed in Table 2. The averaged melylcyclopropane carboxylic acid was derived from Afu,H, ting point T , was determined to be (331.48 0.03 ) divided by T,. K , the averaged enthalpy A,, H, was ( 16.322 During the heat capacity experiment, we found 0.062) kJ/mol, and the averaged entropy A,,S, was: that the fusion from solid phase to liquid phase took A,,S, = Afu,H,/Tm= (49.24 * O . 19) J/( K * mol) . Table 2 Experimental and calculated results of temperature of fusion and enthalpy
*
Ti/K
T,/K
T,/K
Q/J
290.165 292. 151 291.653
360.578 362.358 361.865
331.445 331.492 331.487
5450.85 5460.32 5443.18
THodT/n Ti
nl:C,,,(S)dT
1482.64 1479.41 1479.23
1154.67 1107.43 1117.96
Aru,H,/(kJ
nl:C,,,(L)dT 1030.39 1089.02 1072.25 ~
The purity of the sample is determined using fractional melting method. The values of melting temperatures in the solid-liquid two-phase region are determined through a series of fraction melting. The basic principle is as the following. At the temperature several degrees below the melting point, an enough amount of energy is supplied to the sample cell for melting a small fraction of the sample, and the melting temperature is observed until equilibrium is reached. After the attainment of equilibrium, another amount of energy is supplied to the sample and another portion of sample is
*
- mol-')
16.346 16.358 16.260 ~~
melted, and a second equilibrium melting temperature is observed. By this means, the values of melting temperatures in the solid-liquid region are determined through a series of fraction melt. Then the sample is completely melted and a final equilibrium temperature a few degrees above the melting point is determined. With the plot of equilibrium temperatures T / K us. melting fractions, the melting points of sample and pure substance could be obtained. Then, the purity of 3-( 2 , 2-dichloroethenyl ) -2, 2-dimethylcyclopropane carboxylic acid can be obtained according to the follow-
XUE Bin et Q.Z.
No. 4
ing Van' t Hoff equation. To - T,,,= R ~ d A , , H , (4) where T, is the melting point of a sample and To is the melting point of pure compound. AfusH , is the molar melting enthalpy of a pure compound, and x is the molar fraction of the impurity. In the present study, the experimental and the calculated results are shown in Table 3 and Fig. 2. In Table 3 , Q is the amount of heat introduced into the sample for melting the sample. With Fig. 2 , extrapolating the equilibrium temperatures us. the inverse of melting fraction ( 1/F, F is melting fraction ) to zero, the melting point, To , of pure 3-( 2,2-dichloroethenyl ) -2,2-dimethylcyclopropane carboxylic acid was obtained to be 332.28 K. The purity of the sample was determined to be 98.58% (molar fraction) , it is very close to 98.75% ( molar fraction ) obtained using Table 3 Experimental results of purity measurement F = Q / ( AH,
Q/J 396.347 518.463 705.937 858.017 1010.43 1232.09 1561.73
- n)
0.22262 0.29121 0.39651 0.48 193 0.56754 0.69204 0.87719
1/F
T/K
4.492 3.434 2.522 2.075 1.762 1.445 1. 140
327. 192 328.346 329.422 329.93 1 330.274 330.666 330.995
298.15 300 305 310 315 320 325
263.79 265.79 279.25 292.70 346.53 477.74 736.80
330 335 340 345 350 355 360 365 370 375 380 385 390 395
Maxiurn
400 Hm,T
- Hm,
298.15
HPLC. The result of purity determination shows that the calorimetry is an efficient method for the deterrnination of high purity samples.
329.0 328.0 -
23.37 25.65 27.67 29.62 31.50 33.33 35.12 36.91 38.72 40.54 42.38 44.23 46. 10 41.99
=
(5)
5.0
I1F
Fig. 2 Equilibrium temperature vs. inverse of melting fraction
3 Thermodynamic Functions of Sample The heat capacity near the thermodynamic zero point was difficult to obtain under the present experimental conditions. Therefore, only the thermodynamic function data in a temperature range from 298. 15 to 400 K were given with respect to the standard state (298. 15 K ) . The data of thermodynamic function was calculated using the following equations and the re-
G,,,,298.
501.29 410.45 397.00 383.540 370.080 359.99 356.69 360.68 362.75 365.54 368.50 372.77 375.99 379.21
1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
0.0 0.5
sults,
0.4899 1.852 3.282 4.880 6.941 9.977
ISCp,mdT
463
Hm,
T
- 'm,
298.15
9
, m '
T
- ,m'
298. I S
9
and ,m'
are listed in Table 4.
1.640 6. 140 10.79 15.90 22.38 31.78 72.39 79.15 85.04 90.66 96.01 101.1 106.1 110.9 115.8 120.6 125.4 130.2 135.0 139.7
-1.510 - 20.78 - 62.93 - 128.7 - 222.0 - 352.5
- 883.0 - 1264 - 1675 -2114 -2581 - 3074 - 3592 -4135 - 4702 - 5293 - 5908 - 6547 -7210 - 7896
T
-
CHEM. RES. CHINESE U.
464 T
- ‘m,
‘m,T
298. IS
=
98.15
Cp,mdT
-
98.15
( Cp,m/T) dT (7)
4 Heat Decomposition The heat decomposition of 3-( 2,2-dichloroethenyl ) -2 ,2-dimethylcyclopropane carboxylic acid was determined with a thermobalance ( TG 951 ) in nitrogen atmosphere. The results are shown in Fig. 3. It can be seen from the TG-DTG curves in Fig. 3 that there is only one mass lose activity in the whole temperature range. The decomposition started at about 418 K and
& 8
‘E
100
1
2 -
- 2.0
DTG- 1.5
60-
8
6 40-
- 1.0
2 20-
I
- 0.5
300
References [ 1] [2]
0
80-
I
ended at 544 K. The decomposition peak temperature obtained from the DTG curve is 510 K. The decomposition reaction kinetic parameters can be obtained by processing TG dataLg1 . The order of reaction, preexponential factor, and activation energy are n = 0.23 , A = 7 . 3 x lo7 min-’ and E =70. 64 kJ/mol, respectively.
[3 ]
z
I L.3
I
I
I
I
I
350
400
450
500
550
[4] ~
9
[5 ]
3
[6]
- 0.0
[7]
600
[8 ]
I
TK
Fig. 3 TG and DTG plots of 3-(2,2-dichloroethenyl)-2,2dimethylcyclopropanecarboxylic acid
Vol. 23
[9 ]
Xue Z. , Pesticde, 1955, 3 4 , 29 Swaine S . , Tandy M. , Analytical Metheds for Pesticides and Plant Growth Regulutors , 1984, WI , 33 Shi X. , Wang M. , Cuo H. , et al. , Chinese J o d of Analytical Chemistry, 2002, 30, 1293 Lebedev B. , KulGna T. , Smirnova N. , et al. , Journal of Thermal AnalysL and Calorimetry, 2003, 7 4 , 735 Vinnik R. , Roznyatovsky V. , J o u m ~ olf Thermal Analysir and Calorimetry, 2003, 7 3 , 819 Wu Z. , Yang H. , Jiang M. , Journal of Instrumental Analysis, 2002, 2 1 , 25 Tan Z. , Xue B. , Lu S. , et al. , Journal Thermal Analysis and Calorimetry, 2001, 6 3 , 297 Tan Z. , Zhou L. , Chen S. , S c i e ~ MSinha( Series B ) , 1983, 2 6 , 1014 Chen J . , Li C., Chemistry, 1980, 1 , 7
CHEM. RES. CHINESE U. 2007, 2 3 ( 4 ) , 4 6 0 4 6 4 Article ID 1005-9040( 2007) 4 4 4 6 0 4 5
ScienceDirect
Heat Capacities and Thermodynamic Properties of 3 - ( 2 ,2-Dichloroethenyl) -2 ,2-dimethylcyclopropanecarboxylicAcid XUE Bin"*' , WANG Jian-ya' , TAN Zhi-cheng3 and WU Tong-hao' 1. School of Petrochemical Engineering, Shenyang University of Technology, Liaoyang 111003 , P. R. China ; 2. College of Chemistry, Jilin University, Changchun 130021, P . R. China ; 3. Themchemistry Laboratory, Dalian Institute of Chemical Physics, Chinese Academy of Science, Dalian 116023 , P . R. China Received Nov. 17, 2006 The heat capacities of 3-( 2,2-dichloroethenyl) -2,2-dimethylcyclopmpaecarboxylic acid ( a racemic mixture, molar ratio of cis-/trans-structure is 35/65) in a temperature range from 78 to 389 K were measured with a precise automatic adiabatic calorimeter. The sample was prepared with a purity of 98.75% ( molar fraction). A solid-liquid fusion phase transition was observed in the experimental temperature range. The melting point, T,,, , enthalpy and entropy of fusion, A,,H, , A,,S, , of the acid were determined to be ( 33 1.48 0.03 ) K , ( 16.321 0.03 1 ) kJ/mol,
*
*
and (49.24 *O. 19) J/( K * mol) , respectively. The thermodynamic functions of the sample, H, - H298, S, Sm8, and G, - G,, Is , were reported at a temperature intervals of 5 K. The thermal decomposition of the sample was studied using thermogravimetric(TG) analytic technique, the thermal decomposition starts at ca. 418 K and ends at ca. 544 K , the maximum decomposition rate was obtained at 510 K. The order of reaction, preexponential factor and activation energy are n = 0.23, A = 7 . 3 x lo7 min - I , E = 70.64 kJ/mol , respectively. Keywords 3-( 2,2-Dichlome.thenyl)-2,2-dimethylcyclopropanecarboxylicacid ; Adiabatic calorimetry ; Heat capacity ; Thermodynamic function ; Thermal decomposition
Introduction 3-( 2 , 2-Dichloroethenyl ) -2, 2-dimethylcyclopropanecarboxylic acid is one of the important intermediates for the preparation of fenpropathrin pesticide, and many kinds of high-performance and activity fenpropathrin pesticides such as permethrin , alphamethrin , cfluthrin , fenpyrithrin have been synthesized with this"-31. Its formula is C, H,, 0, Cl,, and its structure is shown in Scheme 1. OH
Scheme 1 Molecular structure of 3 4 2,2-dichloroethenyl)2,2-dimethylcyclopropaneearboxylicacid
There are four isomers of the acid, the two isomers, 1R-cis- and 1R-trans-3-( 2,2-dichloroethenyl) 2,2-dimethyIcyclopropanecarboxylicacids, can be used as the materials for the preparation of fenpropathrin pesticides, but the other two isomers, 1s-cis- and 1Strans-3-( 2 , 2-dichloroethenyl ) -2, 2-dirnethylcyclopropanecarboxylic acids are not used for the synthesis of fenpropathrin pesticides"-31 . The thermodynamic data is one of the important
*
bases for improving the synthesis process of fenpropathrin pesticide and studying the reaction mechanisms of synthesizing fenpropathrin pesticides , and calorimetry is one of the effectual methods for these r e ~ e a r c h e s ' ~ . ~ ] . Stereoselective synthesis and separation of the isomers of product and intermediates can reduce the used amount of insecticide, improve economic performance and decrease environmental pollution. In this work, the heat capacities of 3-( 2,2-dichloroethenyl ) -2 ,2-dimethylcyclopropanecarboxylic acid ( a racemic mixture , the molar ratio of cis-/trans-structure was 35/65) of high purity( 98.75% , molar fraction) were measured in a temperature range of 78-389 K with an automatic adiabatic calorimeter. At the same time, the melting point, T,,, , enthalpy and entropy of fusion, A,,H, , AfusS, , of the acid were calculated. The thermal decomposition of the sample was studied using thermogravimetric( TG) analytic technique.
Experimental 1 Sample Preparation and Analysis 3-( 2 , 2-Dichloroethenyl ) -2, 2-dimethylcyclopropanecarboxylic acid ( a racemic mixture, molar ratio of
Supported by the Education Bureau Science Foundation of Liaoning Province, China( No. 20040261 ) . To whom correspondence should be addressed. E-mail: xue-b@ 163. com
**
XUE
No.4
Bin et
al.
46 1
*
cis-/trans-structure is 35/65 ) was prepared by the hydrolysis of 3- (2,2-dichloroethenyl) -2 ,2-dimethylcyclopropanecarboxylic ester after the reaction of 1 ,1-dichloro4-me-thyl-l,3-~entadieneand diazoacidic ester"]. The crystal product of 3-( 2,2-dichloroethenyl) - 2 , 2 dimethylcyclopropanecarboxylic acid was filtered and recrystallized thrice. Finally, the sample was obtained. The molecular structure was verified using nuclear magnetic resonance( Bruker DRX4OO). The purity of the sample was determined to be 98.75% ( molar fraction) by high performance liquid chromatography( HPLC ) l6] (Shimazu 10A).
0 . 2 % compared with those"] of curacy was within the National Institute Science and Technology ( formerly the National Bureau of Standards, NBS ) in the whole temperature range. The heating rate was controlled in a range of 0 . 2 4 . 4 Wmin while the sample was in solid and li-quid phases. The interval of temperature rising was 2 4 K generally and the interval was reduced a little during sample melting. The duration of heating was mea-sured by means of a digitally displayed electronic timer-controller with an accuracy of s. The data were read and calculated automatically by a computer on the real time.
2 Adiabatic Calorimetry
3 TG Analysis
The heat capacity measurements were carried out Thermogravimetric analysis was performed with a with an automatic calorimeter over a temperature range TG 951 thermal balance in a temperature range of of 8 0 4 0 0 K. The equipment was based on the 340-550 K. A nitrogen gas flow rate of 150 m u m i n Nernst's step-heating method. The adiabatic calorimeand a heating rate of 3 Wmin were used. ter and the principle of the automatic adiabatic control Results and Discussion circuits have been de~cribed"'~] . 1 Heat Capacity To verify the reliability of the calorimeter, the moThe experimental molar heat capacities of 3-( 2 , 2 lar heat capacities of a-Al,O, were measured from 80 to dichloroethenyl) -2 , 2-dimethylcyclopropane carboxylic 400 K. The deviations of the experimental results from acid of a typical run are listed in Table 1 and shown in the smoothed curve are within 0. 1% , while the inacFig. 1. Table 1 Experimental molar heat capacities of 3-(2,2-dichloroethenyl) -2,2-dimethylcyclopropanecarboxylic acid
*
T/K 77.996 78.884 79.761 80.912 82.324 84.345 86.954 90.165 93.956 97.646 101.246 104.766 108.217 111.604 114.934 118.210 121.438 124.621 127.761 130.861 133.924 137.386 141.240 145.041
cF..rn
86.346 88.901 90.810 92.560 93.212 95.671 98.622 101.910 105.540 108.900 111.982 114.833 117.882 120.606 122.796 125.411 127.613 129.861 131.985 134. 116 136.248 138.797 141.318 144.010
T/K 148.792 152.498 156. 159 159.779 163.360 167.448 172.009 176.503 180.968 185.397 189.782 194.124 198.421 202.677 206.894 211.070 215.208 219.306 223.368 227.364 231.276 235. 180 239.044 242.817
CP*m
T/K
cP,m
146.632 149. 182 151.425 153.447 155.535 156.554 162.125 164.299 167.039 170.052 173.020 175.470 178.702 180.798 183.521 185.900 189.196 191.945 194.757 199.788 204. 139 207.885 210.664 215.015
246.610 250.4 14 254. 149 257.823 261.722 265.848 269.952 274.044 278.112 282. 156 286.176 290.165 294.114 298.020 301.875 305.669 309.397 313.227 316.945 320.085 322.690 324.969 326.852 328.296
218.882 222.021 223. 169 228.482 231.639 234.184 236.577 238.855 241.643 244.337 247. 129 250.585 256.141 260.938 270.263 280.754 293.781 315.789 382.31 1 494.825 598.628 696.532 987.054 1267.090
In the solid region, the heat capacities of the sample were measured for 60 points in a temperature range from 78 to 290 K and for eight points in the liquid re-
T/K
Cp.m
329.422 330.274 330.926 331.445 331.907 332.733 334.651 337.516 340.666 343.896 347.147 350.408 353.699 357.077 360.578 364.132 367.670 371.194 374.712 378.232 381.745 385.236 388.690
1712.696 2252.312 2780.153 3004.934 2436.495 1040.347 485.273 429.940 421.514 415.292 399.679 387.076 375.051 361.784 360.724 355.978 358.475 360.753 362.667 364.295 366.771 368.558 371.281
gion between 361 and 390 K. In fusion region, the heat capacities of the sample were determined for 27 points in temperature range from 290 to 360 K. NO
CHEM. RES. CHINESE U.
462
-g
3500 3000 2500-
e
.. $
%
20001500-
' .1000-
n-
I
50
i
where, X = ( T - 184. 1)/106. 1 and T ( K ) is temperature. For liquid region( 361-390 K ) : CP,,=363.5381 + 6.57942X + 0.06604X2 + 1. 07814X3 (2) where, X = ( T - 376.4)/12.3 and T ( K ) is temperature. The deviation of the experimental data from the smoothed values in all the regions is within * O . 2 % .
c
500-
I
I
I
1
I
Vol. 23
I
100 150 200 250 300 350 TK
I 400
Fig. 1 Heat capacity curve of 3-( 2,2-dichloroethenyl)2,2-dimethylcycloproparbo~y~c acid
thermal anomaly was observed in solid and liquid regions, it shows that the structure of the compound is stable in the temperature range. The values of heat capacities were fitted with the following polynomial expressions using least squares method. For solid region( 78-290 K ) : Cp,m= 168.28729 + 72.12045X + 19. 1887X2 + 9. 3298X3 - 18. 331X4
(1)
2 Melting Point, Enthslpy and Entropy of Fusion, and Purity Determination To determine the melting point ( T , ) and molar enthalpy( AfusHm) , a step heating method was used. It is based on the following principle. The sample was heated with less heat once to measure the equilibrium temperature. The increment of the energy required to heat the sample from the temperature T, , below the melting point, to the temperature T, , above the melting point, was measured. With multiple heating, the melting point was approached and the enthalpy of fusion of the sample was derived from the following equation.
where n is the molar number of the sample; Q is the place from about 290 to 365 K . The determination of total amount of heat introduced into the sample; temperature of fusion T , and that of the enthalpy of fuCP,,,( S) , CP,,( L ) , and Ho are the heat capacity of sion A,,H, for the sample were carried out from three the sample in solid state, the sample in the liquid series of heat capacity measurements in this temperastate, and the empty cell, respectively. The entropy of ture range. The three runs of experimental and calcufusion Afu,S, of 3-( 2,2-dichloroethenyl) -2,2-dimethlated results are listed in Table 2. The averaged melylcyclopropane carboxylic acid was derived from Afu,H, ting point T , was determined to be (331.48 0.03 ) divided by T,. K , the averaged enthalpy A,, H, was ( 16.322 During the heat capacity experiment, we found 0.062) kJ/mol, and the averaged entropy A,,S, was: that the fusion from solid phase to liquid phase took A,,S, = Afu,H,/Tm= (49.24 * O . 19) J/( K * mol) . Table 2 Experimental and calculated results of temperature of fusion and enthalpy
*
Ti/K
T,/K
T,/K
Q/J
290.165 292. 151 291.653
360.578 362.358 361.865
331.445 331.492 331.487
5450.85 5460.32 5443.18
THodT/n Ti
nl:C,,,(S)dT
1482.64 1479.41 1479.23
1154.67 1107.43 1117.96
Aru,H,/(kJ
nl:C,,,(L)dT 1030.39 1089.02 1072.25 ~
The purity of the sample is determined using fractional melting method. The values of melting temperatures in the solid-liquid two-phase region are determined through a series of fraction melting. The basic principle is as the following. At the temperature several degrees below the melting point, an enough amount of energy is supplied to the sample cell for melting a small fraction of the sample, and the melting temperature is observed until equilibrium is reached. After the attainment of equilibrium, another amount of energy is supplied to the sample and another portion of sample is
*
- mol-')
16.346 16.358 16.260 ~~
melted, and a second equilibrium melting temperature is observed. By this means, the values of melting temperatures in the solid-liquid region are determined through a series of fraction melt. Then the sample is completely melted and a final equilibrium temperature a few degrees above the melting point is determined. With the plot of equilibrium temperatures T / K us. melting fractions, the melting points of sample and pure substance could be obtained. Then, the purity of 3-( 2 , 2-dichloroethenyl ) -2, 2-dimethylcyclopropane carboxylic acid can be obtained according to the follow-
XUE Bin et Q.Z.
No. 4
ing Van' t Hoff equation. To - T,,,= R ~ d A , , H , (4) where T, is the melting point of a sample and To is the melting point of pure compound. AfusH , is the molar melting enthalpy of a pure compound, and x is the molar fraction of the impurity. In the present study, the experimental and the calculated results are shown in Table 3 and Fig. 2. In Table 3 , Q is the amount of heat introduced into the sample for melting the sample. With Fig. 2 , extrapolating the equilibrium temperatures us. the inverse of melting fraction ( 1/F, F is melting fraction ) to zero, the melting point, To , of pure 3-( 2,2-dichloroethenyl ) -2,2-dimethylcyclopropane carboxylic acid was obtained to be 332.28 K. The purity of the sample was determined to be 98.58% (molar fraction) , it is very close to 98.75% ( molar fraction ) obtained using Table 3 Experimental results of purity measurement F = Q / ( AH,
Q/J 396.347 518.463 705.937 858.017 1010.43 1232.09 1561.73
- n)
0.22262 0.29121 0.39651 0.48 193 0.56754 0.69204 0.87719
1/F
T/K
4.492 3.434 2.522 2.075 1.762 1.445 1. 140
327. 192 328.346 329.422 329.93 1 330.274 330.666 330.995
298.15 300 305 310 315 320 325
263.79 265.79 279.25 292.70 346.53 477.74 736.80
330 335 340 345 350 355 360 365 370 375 380 385 390 395
Maxiurn
400 Hm,T
- Hm,
298.15
HPLC. The result of purity determination shows that the calorimetry is an efficient method for the deterrnination of high purity samples.
329.0 328.0 -
23.37 25.65 27.67 29.62 31.50 33.33 35.12 36.91 38.72 40.54 42.38 44.23 46. 10 41.99
=
(5)
5.0
I1F
Fig. 2 Equilibrium temperature vs. inverse of melting fraction
3 Thermodynamic Functions of Sample The heat capacity near the thermodynamic zero point was difficult to obtain under the present experimental conditions. Therefore, only the thermodynamic function data in a temperature range from 298. 15 to 400 K were given with respect to the standard state (298. 15 K ) . The data of thermodynamic function was calculated using the following equations and the re-
G,,,,298.
501.29 410.45 397.00 383.540 370.080 359.99 356.69 360.68 362.75 365.54 368.50 372.77 375.99 379.21
1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
0.0 0.5
sults,
0.4899 1.852 3.282 4.880 6.941 9.977
ISCp,mdT
463
Hm,
T
- 'm,
298.15
9
, m '
T
- ,m'
298. I S
9
and ,m'
are listed in Table 4.
1.640 6. 140 10.79 15.90 22.38 31.78 72.39 79.15 85.04 90.66 96.01 101.1 106.1 110.9 115.8 120.6 125.4 130.2 135.0 139.7
-1.510 - 20.78 - 62.93 - 128.7 - 222.0 - 352.5
- 883.0 - 1264 - 1675 -2114 -2581 - 3074 - 3592 -4135 - 4702 - 5293 - 5908 - 6547 -7210 - 7896
T
-
CHEM. RES. CHINESE U.
464 T
- ‘m,
‘m,T
298. IS
=
98.15
Cp,mdT
-
98.15
( Cp,m/T) dT (7)
4 Heat Decomposition The heat decomposition of 3-( 2,2-dichloroethenyl ) -2 ,2-dimethylcyclopropane carboxylic acid was determined with a thermobalance ( TG 951 ) in nitrogen atmosphere. The results are shown in Fig. 3. It can be seen from the TG-DTG curves in Fig. 3 that there is only one mass lose activity in the whole temperature range. The decomposition started at about 418 K and
& 8
‘E
100
1
2 -
- 2.0
DTG- 1.5
60-
8
6 40-
- 1.0
2 20-
I
- 0.5
300
References [ 1] [2]
0
80-
I
ended at 544 K. The decomposition peak temperature obtained from the DTG curve is 510 K. The decomposition reaction kinetic parameters can be obtained by processing TG dataLg1 . The order of reaction, preexponential factor, and activation energy are n = 0.23 , A = 7 . 3 x lo7 min-’ and E =70. 64 kJ/mol, respectively.
[3 ]
z
I L.3
I
I
I
I
I
350
400
450
500
550
[4] ~
9
[5 ]
3
[6]
- 0.0
[7]
600
[8 ]
I
TK
Fig. 3 TG and DTG plots of 3-(2,2-dichloroethenyl)-2,2dimethylcyclopropanecarboxylic acid
Vol. 23
[9 ]
Xue Z. , Pesticde, 1955, 3 4 , 29 Swaine S . , Tandy M. , Analytical Metheds for Pesticides and Plant Growth Regulutors , 1984, WI , 33 Shi X. , Wang M. , Cuo H. , et al. , Chinese J o d of Analytical Chemistry, 2002, 30, 1293 Lebedev B. , KulGna T. , Smirnova N. , et al. , Journal of Thermal AnalysL and Calorimetry, 2003, 7 4 , 735 Vinnik R. , Roznyatovsky V. , J o u m ~ olf Thermal Analysir and Calorimetry, 2003, 7 3 , 819 Wu Z. , Yang H. , Jiang M. , Journal of Instrumental Analysis, 2002, 2 1 , 25 Tan Z. , Xue B. , Lu S. , et al. , Journal Thermal Analysis and Calorimetry, 2001, 6 3 , 297 Tan Z. , Zhou L. , Chen S. , S c i e ~ MSinha( Series B ) , 1983, 2 6 , 1014 Chen J . , Li C., Chemistry, 1980, 1 , 7