Znd. Eng. Chem. Res. 1988, 27, 1536-1540
1536
from n = 2 to n = number of carbon atoms in the initial chain minus one. This should be explained by the weak energies of the a and 6 bonds in the aliphatic chain compared to those in the aromatic nucleus. Likewise, the relative fragility of the C-H bond on carbon 1 of the chain coupled with a stabilization of the radical formed by delocalization with the s electrons in the aromatic part seems to justify the formation of large amounts of vinylic compounds. As we have shown by an example, Le., dodecylbenzene, the complete written expression of the decomposition mechanism of long aliphatic chain aromatics is possible. However, and in light of the great number of elemental radicular processes describing thermal decompositions,we have preferred to sum up the decomposition of ArC,H2,+1 by similarity to the preceding study. Registry No. DDB, 123-01-3; T D P , 114980-37-9; ODN, 20905-47-9; DEB, 5634-22-0.
Literature Cited Allara, D. L.; Shaw, R. “A Compilation of Kinetic Parameters for the Thermal Degradation of n-Alkane Molecules”. J. Phys. Chem. Ref. Data 1980, 9, 523. Barton, B. D.; Stein, S. E. “Pyrolysis of Alkyl Benzenes. Relative Stabilities of Methyl-Substituted Benzyl Radicals”. J. Phys. Chem. 1980,84, 2141. Benson, S. W. Thermochemical Kinetics, 2nd ed.; Wiley: New York, 1976. Billaud, F.; Freund, E. %-Decane Pyrolysis a t High Temperature in a Flow Reactor”. Ind. Eng. Chem. Fundam. 1986,25, 433. Billaud, F.; Ajot, H.; Freund, E. “Unit6 Micropilote pour 1’Btude de Charges de Vapocraquage. Exemple d’un MBlange de nParaffines”. Rev. Inst. Fr. Pstrole 1983, 38, 763. Billaud, F.; Baronnet, F.; Niclause, M. “Influence CinBtique et Chimique d’alcenes sur la Pyrolyse d’alcanes: Mise au Point et Nouveaux Resultats”. Can. J. Chem. 1985, 63(11), 2869.
Billaud, F.; Berthelin, M.; Freund, E. “Thermal Cracking of Vacuum Distillates”. J. Anal. Appl. Pyrol. 1986, 10, 139. Blouri, B.; Hamdan, F.; Lanchec, G. “MBcanisme du Craquage Thermique Mod6rB des Hydrocarbures ou des Huiles Lourdes du PBtrole”. Symposium on the Thermal Treatment of Heavy Hydrocarbon-Containing Condensed Structures, Ecole Centrale des Arts et Manufactures, Paris, 1984. Chaverot, P. Ph.D. Thesis, Ecole Nationale Supgrieure du PBtrole et des Moteurs (ENSPM), Rueil-Malmaison, France, 1985. Chaverot, P.; Berthelin, M.; Freund, E. “Comportement en Vapocraquage de Molecules Modeles e t de Distillats Sous Vide HydrotraitBs. Ere Partie. Potentialit6 de Craquage. Reacteur B Profil de Temperature Rectangulaire et i5 Court Temps de SBjour”. Chaverot, P.; Berthelin, M.; Freund, E. “Comportement en Vapocraquage de Molecules Modeles et de Distillates Sous Vide Hydrotraitgs. 2Bme Partie. Pyrolyse de MolBcules ModBles Representatives des Distillats Sous Vide Bruts et Hydrotraitbs”. Rev. Inst. Fr. Petrole 1986, 41, 649. Crowne, C. W. P.; Grigulis, V. J.; Throssell, J. J. “Pyrolysis of Ethylbenzene by the Toluene Carrier Method”. Trans. Faraday Soc. 1969,65, 1051. Leigh, C. H.; Szwarc, M. “The Pyrolysis of Propylbenzene and the Heat of Formation of Ethyl Radical”. J. Chem. Phys. 1952, 20, 403. Mushrush, G . W.; Hazlett, R. N. “Pyrolysis of Organic Compounds Containing Long Unbranched Alkyl Groups”. Ind. Eng. Chem. Fundam. 1984,23, 288. Savage, P. E.; Klein, M. T. “Petroleum Asphaltene Thermal Reaction Pathways”. Symposium on New Chemistry of Heavy Ends, Division of Petroleum Chemistry of the American Chemical Society, Chicago, 1985. Savage, P. E.; Klein, M. T. “Discrimination between Molecular and Free-Radical Models of 1-Phenyldodecane Pyrolysis”. Ind. Eng. Chem. Res. 1987a, 26, 374. Savage, P. E.; Klein, M. T. “Asphaltene Reaction Pathways. 2. Pyrolysis of n-Pentadecylbenzene”. Ind. Eng. Chem. Res. 198713, 26, 488. Received for review November 30, 1987 Accepted March 23, 1988
Solution to Missing Group Problem for Estimation of Ideal Gas Heat Capacities B. Keith Harrison* Department of Chemical Engineering, University of South Alabama, Mobile, Alabama 36688
William H. Seaton+ 1329 Belmeade Drive, Kingsport, Tennessee 37664
An estimation method was developed to predict ideal gas heat capacities over the temperature range from 300 to 1500 K. The only information required are the types and numbers of different elements comprising a molecule. This method gives numeric results only slightly inferior to more rigorous methods and has the advantage of being general in the sense that calculations can be made for any molecule. The more rigorous methods are often unable to provide an estimate due to a lack of available parameters. This new method can be incorporated as a default method in calculation schemes favoring more accurate methods but allowing for their failure. Calculations involving ideal gas heat capacities are an important part of determining enthalpy changes for processes. Process simulation and other process-related computational packages are dependent on some established formalism for obtaining needed ideal gas heat capacities for the molecular species involved. Frequently the formalism is to first check a literature-based collection of
* Author t o whom correspondence should be addressed. + Independent
Consultant.
0888-5885/88/2627-1536$01.50/0
data, and failing to find the molecule there, then a correlation method is used. The correlation methods available for ideal gas heat capacity all involve some form of group contribution method based on the structure of the molecule. A relatively easy to use method assigns heat capacity contributions to various chemical bonds (Renson, 1976). More accurate methods involve assigning contributions to common molecular groupings of elements (Thinh et al., 1971; Thinh and Trong, 1976; Rihani and Doraiswamy, 1965; Joback, 0 1988 American Chemical Society
Ind. Eng. Chem. Res., Vol. 27, No. 8, 1988 1537 1984) and even making allowance for next nearest neighbors to a group (Benson et al., 1969; Benson, 1976; Yoneda, 1979). Unfortunately all of these correlations suffer from a lack of complete generality in the sense that certain bond contributions and molecular grouping contributions are missing from the tables of available parameters. When a calculation for a particular molecule is made, occasionally a needed value to complete the calculation will be missing. In such cases, intercession with judgment is required to provide approximate values to enable the computations to proceed. It was decided to address the problem of the lack of generality in ideal gas heat capacity calculations during the development of version 6 of the ASTM computer program CHETAH. CHETAH is a chemical thermodynamic and energy release evaluation program (Seaton et al., 1974) that is now undergoing substantial refinement and expansion. This program has been found to be useful for basic thermodynamic calculations as well as for screening chemical compounds for potential hazards based on the prediction of the maximum reaction energy of compounds and mixtures. It is intended that the version under development should have the generality to make thermodynamic predictions for virtually any compound if experimental data are lacking for that compound. The generalized prediction method for ideal gas heat capacity developed for the program CHETAH is described in this paper. It is based on the contributions of the individual atoms in a molecule. In the hierarchy of estimation methods (Benson, 19761, this would be considered a zero-order method. In the past, such methods have been thought to be inadequate for any ideal gas thermodynamic properties. The simplicity and generality of zero-order methods are very attractive, however, if the accuracy of the predictions are at all acceptable. The calculation strategy to be used in CHETAH is to use the best method available for each particular case. When critically evaluated literature values are available, they will be used. When such data are not available, Benson’s method (1976) is used. When a molecular group needed by Benson’s method is not available, the ideal gas heat capacity calculation method described in this paper is used as a default method to provide the contribution of the missing group. Occasionally there will be a molecule for which no Benson molecular groups are available. In this case, the zero-order method described here would be used to furnish a value of the ideal gas heat capacity for the entire molecule. Development of Correlation The file of thermodynamic data for compounds in the ideal gas state, which were used for this project, was acquired by ASTM Committee E-27 for use with the development of CHETAH. The many data sources compiled to form this data base have been described elsewhere (Seaton et al., 1974),but major sources include the JANAF Thermochemical Tables (Chase et al., 1985), Thermochemistry of Organic and Organometallic Compounds (Cox and Pilcher, 1970), and The Chemical Thermodynamics of Organic Compounds (Stull et al., 1969). The database covers a range of temperatures from 300 to 1500 K. The number of molecules for which heat capacity data are available varied with temperature, but in all cases it was within the range 319-412. The database is predominately composed of hydrocarbons and substituted hydrocarbons, although there is a substantial representation of inorganic molecules as well. To limit the number of parameters, the estimation method uses one parameter at each temperature for each
of 13 commonly encountered elements from the periodic table. Parameters are provided at seven temperatures for each of these elements. A 14th parameter is provided at each temperature as a constant term, and a 15th parameter is provided as a general parameter for all remaining elements. The strategy used to determine parameters was as follows. For pure hydrocarbon molecules, parameters for carbon, hydrogen, and a constant were simultaneously adjusted at a given temperature to give the best fit of all available hydrocarbon data. After these three parameters were determined, the other elements were added, one by one. Thus, for oxygen, the next element in the list of 13, all molecules composed of any or all the elements, carbon, hydrogen, and oxygen, were included. Only the parameter for oxygen was adjusted; the parameters for carbon, hydrogen, and the constant had already been determined and were fixed. The contribution of each element in the list was evaluated sequentially by this process. Finally, the parameter representing all elements not in the list of 13 was determined. In all cases, the goodness of fit was measured by an objective function of a standard deviation type. The numeric technique used was a simplex minimization of the objective function. The strategy followed in determining the parameters accentuates hydrocarbons because of their importance in their own right and as a basis for more complex organic molecules. This fitting procedure was carried out independently at each of seven temperatures between 300 and 1500 K. The success of this procedure or any other alternative is ultimately measured in terms of the match of the correlation to available experimental data. Trials with a number of procedures showed the method used here to be relatively simple, reasonable in computation time, and successful in fitting the data.
Results The formula representing the new zero-order estimation method for ideal gas heat capacities follows. Note that the calculation is expressed in terms of a heat capacity increment. An increment may refer to a grouping of elements within a molecule (such as used by Benson’s method) or to an entire molecule. The needs of the particular application determine the interpretation: CPINC = PARAM(l)*C + PARAM(2)*H + PARAM(3) + PARAM(4)*O + PARAM(5)*N + PARAM(G)*S + PARAM(7)*F + PARAM(8)*CL + PARAM(S)*I + PARAM(lO)*BR PARAM(ll)*SI + PARAM(12)*AL + PARAM(13)*B -t PARAM(14)*P + PARAM(lS)*ELMNUM where CPINC = ideal gas heat capacity for increment at a given temperature (joules/ (mole kelvin)), PARAM($ = fitted parameter i, C = number of carbon atoms in increment, H = number of hydrogen atoms in increment, 0 = number of oxygen atoms in increment, N = number of nitrogen atoms in increment, S = number of sulfur atoms in increment, F = number of fluorine atoms in increment, CL = number of chlorine atoms in increment, I = number of iodine atoms in increment, BR = number of bromine atoms in increment, SI = number of silicon atoms in increment, AL = number of aluminum atoms in increment, B = number of boron atoms in increment, P = number of phosphorus atoms in increment, and ELMNUM = number of atoms in increment excluding 13 atoms in the list above. A list of parameters to be used with the estimation method is given in Table I. Note the 15 parameters
+
1538 Ind. Eng. Chem. Res., Vol. 27, No. 8, 1988 Table I. List of Parameters for Ideal Gas Heat Capacity Correlation PARAM temp, K (1) (2) (3) (4) (5) (6) (7) (8) 300 400 500 600 800 1000 1500
9.04 12.6 15.5 17.5 20.1 21.6 23.9
5.69 7.37 8.89 10.5 13.1 15.2 17.9
4.86 0.864 -1.85 -4.61 -7.49 -8.53 -7.37
11.4 13.9 15.7 17.5 19.4 20.4 20.6
11.9 14.0 16.0 17.3 19.4 20.4 21.1
Table 11. Performance of Estimation Method temp, K av 90 error std dev on % basis 300 400 500 600 800 1000 1500
6.05 4.22 3.25 2.77 2.38 2.35 2.25
7.87 5.56 4.32 3.70 3.34 3.40 3.33
15.3 17.0 19.4 20.3 22.3 22.9 22.5
12.7 16.2 17.9 20.1 21.5 22.4 22.1
data pts 412 343 380 344 384 384 319
Table 111. Performance of Estimation Method for Compounds Which Include Elements Not Specifically Incorporated temp, K av 70 error std dev on % basis data Dts 300 400 500 600 800 1000 1500
6.06 3.55 3.28 3.10 4.00 3.90 3.51
7.29 4.38 4.28 3.86 5.01 4.99 4.37
39 29 30 29 30 30 30
needed are given for each of 7 temperatures between 300 and 1500 K. Interpolation of results or parameters between the listed temperatures is of course possible. The performance of the correlation, relative to the values of ideal gas heat capacity listed in the data base, is shown in Table 11. At each temperature, a summary is given of the standard deviation between the data base listed values and the predicted values. The summary of standard deviations runs between 3.3% and 7.9%. In addition, the summary statistics concerning average absolute errors are shown in Table 11. Values of average absolute errors run between 2.3% and 6.1 %. The number of data points, one for each compound, varies with temperature due to a variation in available data with temperature. An examination of the results for individual compounds indicates very few large deviations, the worst value being for 1,3butadiene with a 29.1 % deviation between the literature value and the predicted value at 300 K. The estimation method uses specific contributions for 13 listed elements. All elements not in this group of 13 are considered to have identical contributions given by parameter 15. To investigate whether this strategy is adequate, performance statistics were generated for those molecules in the data base that include elements not in the list of the 13 specific elements used in the estimation method. The results shown in Table I11 indicate no significant deterioration of the correlation performance for molecules in this class. The number of molecules not composed entirely of the 13 elements in the correlation is relatively small, but indications are that the estimation method is reasonably valid for such cases. To see if the correlation varies in its performance depending on the type of molecule, various groupings of compounds were investigated. Table IV presents some statistics relative to this effort. There is a modest amount of variation in average error among the groups shown, but all are clustered close to the average percent error of 6.05
16.8 18.9 20.2 21.4 22.4 22.8 22.6
(9) 18.7 20.5 22.1 23.3 25.0 25.4 24.6
(10) 17.8 19.9 21.2 22.4 23.4 23.8 23.0
(11) 14.6 17.5 19.6 20.9 23.2 23.9 24.1
(12) 15.8 18.3 20.0 21.1 22.3 22.8 23.2
(13) 11.5 14.7 17.0 18.3 20.8 22.2 24.2
(14) 18.0 20.9 21.6 22.8 23.0 23.4 24.2
(15) 19.5 20.8 21.7 22.1 23.0 23.3 23.3
Table IV. Performance of Estimation Method at 300 K for Various Groupings of Compounds compds containing av absolute indicated elements % error data pts C, H only 6.63 133 6.11 43 C, H, 0 only F plus others 6.16 53 4.10 42 C1 plus others 4.29 16 P plus others 4.32 16 Ti plus others 11 A1 plus others 7.00 8.42 10 Pb plus others 5 Si plus others 3.30 5 9.00 Ge plus others Table V. The Fifteen Compounds with Largest Errors at 300 K error % methodb lit. C, J/ new zero compound (mol K)" order Benson acetylene 44.06 -22.1 0.1 104.01 benzoic acid 20.3 0.1 boronic acid 70.71 -20.4 c 73.85 -29.1 c 1,3-butadyne 81.59 -21.9 -7.6 butatriene 56.90 -17.8 c cyanogen 72.68 19.1 0.2 cyclobutane 124.06 cycloheptane 19.1 29.9 cyclopentane 83.64 27.9 5.1 75.65 26.3 3.3 cyclopentene 56.23 cyclopropane 17.6 0.2 ethylene oxide 17.7 -1.9 48.53 29.12 -20.1 c hydrogen fluoride 154.81 -20.7 c tetraphosphorus trisiulfide urea 93.34 -23.0 c
*
'CHETAH data base. [(calc. - lit.)/lit.]lOO. C N o contribution available for one or more groups.
recorded for the entire data base at this temperature. The relatively large number of hydrocarbons in the data base is not skewing the results to compensate for poorer performance by the more unusual compounds. In fact, the hydrocarbons have a worse average percent error than the results from the data base as a whole. Certain structural types were, however, identified as prone to exhibit less accurate ideal gas heat capacity values. Such compounds include nonaromatic ring compounds and compounds including triple bonds. Table V shows the estimation results for the 15 compounds which exhibited the greatest error. Note that all these compounds were included in the summary statistics given in Tables 11-IV. It is desirable to compare the performance of the simple zero-order estimation method developed here to the more rigorous methods. For this purpose, a table comparing the performance of several methods for a diverse list of 28 organic compounds is extended (Reid et al., 1987). Table VI shows the discrepancy between predicted values and literature values for a few popular methods and the new zero-order method. Note that the average error for the new
Ind. Eng. Chem. Res., Vol. 27, No. 8, 1988 1539 Table VI. Comparison of Estimated and Literature Values for Ideal Gas Heat Capacity % errorb calculated by method Benson Benson compd T, K C,,” J/(mol K) bond values group values Joback propane 73.94 0.9 1.2 1.1 298 155.25 0.6 -0.4 800 n-heptane 0.1 -0.2 166.09 0.4 298 -0.2 340.93 0.6 800 -4.0 2,2,3-trimethylbutane 0.9 164.67 0.8 298 0.1 346.37 0.7 800 -4.6 -0.71 -1.8 trans-2-butene 87.88 298 -0.3 173.75 -0.1 800 4.6 4.7 126.57 5.86 3,3-dimethyl-1-butene 298 266.28 3.5 2.5 800 -4.4 6.3 2-methyl-l,3-butadiene 104.7 0.7 298 -2.2 0.5 201.0 800 C 98.77 2.0 -0.2 2-pentyne 298 192.17 0.7 0.8 800 1.9 p-ethyltoluene 151.65 0.9 0.8 298 324.90 0.3 0.5 800 -20 0 159.89 -2.3 2-methylnaphthalene 298 343.44 -1.6 800 0.9 cis-1,3-dimethylcyclopentane 19 134.56 298 -5.9 1.3 -1.1 317.53 3.5 800 2-butanol -0.3 113.38 -1.9 298 -0.8 220.56 800 -0.1 0.5 C p-cresol 124.56 298 0.9 0.1 -0.1 0.1 255.86 800 -0.4 0 isopropyl ether 158.39 298 -0.8 311.46 1.3 2.3 800 p-dioxane 94.12 -0.4 28 -1.0 298 218.34 0 800 0.1 -5.2 methyl ethyl ketone 298 102.95 -2.5 -5.1 192.93 -0.1 800 0.6 113.71 -9.8 ethyl acetate 298 -0.5 -0.4 213.57 0.1 0.2 800 0.1 trimethylamine -0.2 91.82 0.3 298 0.1 191.00 0.5 800 C propionitrile 1.9 73.10 -1.4 298 2.1 134.56 800 0.8 C 123.55 2-nitrobutane 298 1.0 2.0 0.1 -0.3 248.86 800 C 3-picoline C 2.2 99.65 298 222.40 800 -0.4 27 1,l-difluoroethane 298 -1.3 -0.5 67.99 800 124.31 0.6 0.3 -7.2 -12. 298 156.25 octafluorocyclobutane -6.8 245.56 -1.5 -5.5 800 C bromobenzene 2.8 -0.1 298 97.76 1.1 800 200.05 0 2.8 trichloroethylene 0.3 1.4 298 80.26 0.1 -2.8 800 112.79 0 -0.1 0.2 298 butyl methyl sulfide 140.84 -0.1 -2.1 278.55 800 -1.9 298 2-methyl-2-butanethiol 146.31 0.4 -1.5 -0.2 -0.1 800 277.50 0.4 -0.2 0.4 298 propyl disulfide 185.48 -1.8 350.44 0.4 800 10.0 3-methylthiophene 94.91 1.8 0.3 298 1.0 192.38 2.5 800 no. of compounds 22 27 28 1.4 7.1 1.1 av absolute error, %
of Thinh et aLd -0.5 0.2 -0.1 0.8 0.7 1.0 0 0.1 6.6 4.3 -2.0 -1.2 -0.3 0.4 -1.3 -0.5 -2.2 -0.4 0 0.1
10 1.1
new zero order 4.9 1.7 -4.1 0.7 -3.3 -0.9 -1.5 2.5 0.7 1.7 -8.6 -1.4 -3.2 3.1 1.9 1.9 0.9 0.5 9.9 -0.1 -3.5 1.4 0.5 0.8 -5.1 1.6 16.3 -0.7 -4.8 2.3 -3.8 1.6 3.7 -0.3 -0.9 2.5 2.8 0.2 11.3 1.0 4.7 3.3 -8.5 -0.1 7.3 1.0 -1.5 0.3 -5.1 -2.0 -6.9 -1.6 -8.6 -2.5 4.9 0.9 28 3.2
OStull et al., 1969. *[(talc. - lit.)/lit.]100. CNocontribution available for one or more bonds or groups. dThinh et al. (1976) method application only to hydrocarbons.
zero-order correlation is 3.2%. This is in fact better than the average error of the Benson bond method (7.1%) and compares well to the other listed methods in this table (1.1-3.2%). A comparison including additional estimation methods and grouped by classification of method is given in Table VII. The comparisons in this table are based on the same 28 organic compounds. It is evident from Table VI1 that the more complex methods offer accuracy advantages over the new zero-order method. But the improvement, at least for this data set, is only from 3.2% to 1.1% average error.
The new zero-order method is not proposed as a replacement for the more complex methods, which will tend to be more accurate. It is intended to be a method that will give reasonably accurate estimates when the more complex methods cannot be used. Note in Table VI1 that, even for a relatively simple list of 28 organic chemicals, 5 of the 6 complex methods used failed to be able to provide values for all the compounds in the list. All of the methods listed, except for the new zero-order method, will fail for large classes of chemicals. For instance, only the new zero-order method will provide values for organic
1540 Ind. Eng. Chem. Res., Vol. 27, No. 8, 1988 Table VII. Performance of Ideal Gas Heat Capacity Methods av absolute method no. of compds error % Zero-Order Methods method of this paper 28 3.2 Bond Methods Benson bond
22
Molecular Group Methods 28 Joback 10 Thinh et al. Rihani-Doraiswamy 27
7.1 1.4 1.1
3.2
Molecular Group plus Next Nearest Neighbor Methods Yoneda 27 1.4' Benson 24 1.1 OValue does not include the large anomalous error for ethyl acetate of -28% at 300 K and -11% at 800 K.
phosphates and silicon compounds. The most general method previously published is the Joback method. It, however, fails to provide heat capacity estimates for approximately 36% of the 412 compounds in the data base used for the development of the new zero-order method.
Conclusion The performance statistics indicate that, for ideal gas heat capacity estimation calculations, the zero-order method proposed is tenable. The numeric results compare remarkably well with those of the more rigorous methods. The strongest advantage of the new method is, however, its generality. This method will always give an estimate, whereas the more rigorous methods often fail to provide one. From the limited amount of data available, indications are that the estimate will be a reasonable one. Of course caution is in order for such a procedure, but necessity often dictates that an estimate be made. In terms of computer calculation time, the new method has the advantage of being very rapid in its simplicity. Of course, the simplicity is also attractive if attempting calculations by hand. For the purposes of process-related computer calculations concerning enthalpy changes, such as performed, by example, in the program CHETAH, this new method can furnish a valuable default value having reasonable validity when more rigorous calculations fail due to lack of parameters. This method thus extends the range of this and
other related program packages to a wider range of chemicals. Registry No. Acetylene, 74-86-2; benzoic acid, 65-85-0; boronic acid, 13780-71-7;1,3-butadiyne, 460-12-8; butatriene, 2873-50-9; cyanogen, 460-19-5;cyclobutane, 2074-87-5; cycloheptane, 287-23-0; cyclopentane, 287-92-3; cyclopentene, 142-29-0; cyclopropane, 75-19-4; ethylene oxide, 75-21-8; hydrogen fluoride, 7664-39-3; tetraphosphorus trisulfide, 1314-85-8; urea, 57-13-6; propane, 74-98-6; heptane, 142-82-5; 2,2,3-trimethylbutane, 464-06-2; trans-2-butene, 624-64-6; 3,3-dimethyl-l-butene, 558-37-2; 2methyl-1,3-butadiene, 78-79-5; 2-pentyne, 627-21-4;p-ethyltoluene, 622-96-8; -2-methylnaphthalene, 91-57-6; cis-l,3-dimethylcyclopentane, 2532-58-3; 2-butanol, 78-92-2;p-cresol, 106-44-5; isopropyl ether, 108-20-3;p-dioxane, 123-91-1; methyl ethyl ketone, 78-93-3; ethyl acetate, 141-78-6; trimethylamine, 75-50-3; propionitrile, 107-12-0; 2-nitrobutane, 600-24-8; 3-picoline, 108-99-6; 1,l-difluoroethane, 75-37-6; octafluorocyclobutane, 115-25-3; bromobenzene, 108-86-1; trichloroethylene, 79-01-6; butyl methyl sulfide, 628-29-5; 2-methyl-2-butanethio1, 1679-09-0; propyl disulfide, 629-19-6; 3-methylthiophene, 616-44-4.
Literature Cited Benson, S. W. ThermochemicalKinetics, 2nd ed.; Wiley: New York, 1976; Chapter 2. Benson, S. W.; Cruickshank, F. R.; Golden, D. M.; Haugen, G. R.; O'Neal, H. E.; Rodgers, A. S.; Shaw, R.; Walsh, R. Chem. Reu. 1969, 69, 279. Chase, M. W., Jr.; Davies, C. A.; Downey, J. R., Jr.; Frurip, D. J.; McDonald, R. A.; Syverud, A. N. JANAF Thermochemical Tables, 3rd ed.; American Chemical Society: Washington, D.C., 1985. Cox, J. D.; Pilcher, G. Thermochemistry of Organic and Organometallic Compounds; Academic: London, 1970. Joback, K. G. M.S. Thesis, Massachusetts Institute of Technology, Cambridge, June 1984. Reid, R. C.; Prausnitz, J. M.; Poling, B. E. The Properties of Gases and Liquids, 4th ed.; McGraw-Hill: New York, 1987; p 196. Rihani, D. N.; Doraiswamy, L. K. Ind. Eng. Chem. Fundam. 1965, 4 , 17. Seaton, W. H.; Freedman, E.; Treweek, D. N. CHETAH-The ASTM Chemical Thermodynamic and Energy Release Evaluation Program, ASTM DS 51; American Society for Testing and Materials: Philadelphia, PA, 1974. Stull, D. R.; Westrum, E. F.; Sinke, G. C. The Chemical Thermodynamics of Organic Compounds; Wiley: New York, 1969. Thinh, T. P.; Duran, J. L.; Ramalho, R. S. Ind. Eng. Chem. Process Des. Deu. 1971, 10, 576. Thinh, T. P.; Trong, T. K. Can. J. Chem. Eng. 1976, 54, 344. Jpn. 1979,52, 1297. Yoneda, Y. Bull. Chem. SOC. Received for review January 20, 1988 Accepted March 24, 1988
