Project 851: Critical Properties of Pure Compounds
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Project Definition: Experimentally determine the critical point (temperature, pressure, density/volume) of pure compounds; concentrate on key compounds for which reliable data are lacking. Many such compounds are unstable at their critical temperature; thus, new rapid methods of measurement are required.
Purpose: Provide basic data required for the correlation and prediction of essential physical and thermodynamic properties used for process design and operation. Critical properties are exceedingly important; they are used to estimate such properties as departure functions, liquid density, viscosity, heat capacity, heat of vaporization, thermal conductivity, diffusion coefficients, and surface tension. Critical properties are also essential for correlation of vapor pressure and liquid density over the entire saturated liquid range. The estimation methods commonly used for critical properties (e.g., Lydersen's method) do not give reliable results for compounds which are unstable or contain multiple function groups. For example, previously accepted critical data for the aldehydes were confirmed and corrected. In addition, a study made by one of the DIPPR® member companies indicated that published data for diols were almost totally inaccurate. This project is directed toward the use of new experimental methods which can give better results for such compounds as well as the more stable compounds.
Technical Description: The approach to the critical state is time-dependent and is affected by gravity. However, a close approach can be reached within a few seconds, if an ultra-rapid heating source is provided. Gravity is less important with a shallow sample. Thus, to measure critical properties of an unstable compound, a small sample in a rapid heating device, with fast temperature and pressure sensors, is needed. Work to date has involved use of a rapidly heated sealed-ampoule apparatus and also a low residence time flow apparatus.
Wiltec Research Company has developed a new flow measurement method for critical properties and vapor pressures which requires ultra low residence times. This technique would be of considerable use to a number of DIPPR® projects in the following areas: (1). To supply data for development of a critical point estimation method.; (2) . for measurement of critical temperatures and pressures of unstable and multi functional compounds; and (3) for measurement of boiling points and vapor pressures of compounds that decompose when treated using existing methods.
The method is capable of residence times as low as 0.1 sec for total heat-up time from ambient temperature, and extends Wiltec’s present range of critical temperature measurement capability by about 100º C. This is quite significant and will extend the capability on paraffin hydrocarbons from C18 to about C30.
This method opens a completely new region for study which until now has been inaccessible due to decomposition. Critical properties are measured as a function of time for unstable reacting compounds. The data are then analyzed to extrapolate the measured values to zero reaction. Several alternative techniques have also been developed for this procedure.
The compounds included in this project are selected by the Project Steering Committee, consisting of one representative from each of the project sponsors. See Table I for a list of compounds studied previously.
Wiltec Research Company, Inc.
488 South 500 West
Provo, UT 84601
Phone: 801-374-6648; Fax: 801-374-6674
Web site: http://www.wiltecresearch.com
Dr. Eugene D. Nikitin Institute of Thermal Physics of RAS
Amundsena Str., 106, 620016 Ekaterinburg, Russia
Phone: +7-343-267-8810
Fax: +7-343-267-8800
Web: http://itp.uran.ru/nikitin-eng
Mark Liepa, LyondellBasell Industries, 3801 West Chester Pike, Newtown Square, PA 19073-2387; Phone: 610-359-2102; Fax: 610-359-2434.
Results Expected: Measurements on about 7 compounds each year (this is an average; some compound measurements are attempted, but the measurements can’t be made for a variety of reasons).
(Publication References cited below noted as follows:1985 [1]; [P]indicates publication is pending; [NR] indicates data has not been approved for release/publication )
1985 [1] (Critical temperature and volume unless otherwise noted)
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1. n-Octane (Tc) |
6. Ethyl-3-ethoxy propionate |
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2. Toluene (Tc) |
7. Valeric acid |
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3. Acetaldehyde |
8. 2-Propoxyethanol |
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4. Acetophenone |
9. 2-Butoxyethanol |
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5. Dimethylformamide |
10. Ethylene glycol |
1986 [1] (Critical temperature and volume)
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1. N-Methylpyrrolidone |
7. Undecan-1-ol |
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2. Cyclopentene |
8. 2-Ethoxyethyl acetate |
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3. n-Propyl mercaptan |
9. 2-Butoxyethyl acetate |
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4. n-Butyl mercaptan |
10. 1-Methoxy-2-propyl acetate |
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5. Cyclohexane |
11. Titanium tetrachloride |
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6. Tetralin |
12. 2-Ethylhexanoic acid |
1987 [1] (Critical temperature and volume unless otherwise noted)
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1. Propanal |
8. Monoethanolamine (Tc) |
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2. n-Butanal |
9. Benzaldehyde (Tc) |
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3. n-Pentanal |
10. Formic acid (Tc) |
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4. n-Octyl mercaptan |
11. Diethylene glycol (Tc) |
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5. Cyclohexyl mercaptan |
12. Dimethyl disulfide (Tc) |
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6. 2-(2-Propoxyethoxy)ethanol |
13. Maleic acid (Tc) |
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7. 2-Cyclohexylcyclohexanone (Tc) |
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1988 [1] (Critical temperature and pressure)
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1. Toluene |
7. n-Hexanal |
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2. Cyclohexane |
8. n-Octanal |
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3. Cyclopentene |
9. n-Decanal |
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4. Propanal |
10. 2-Ethoxyethyl acetate |
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5. n-Butanal |
11. 2-Butoxyethyl acetate |
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6. n-Pentanal |
12. 2-Ethylhexanoic acid |
1989 [2] (Critical temperature and pressure)
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1. Acetophenone |
6. Valeric acid |
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2. 2-Butoxyethanol |
7. 1-Methoxy-2-propyl acetate |
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3. 2-Propoxyethanol |
8. 2-(2-Propoxyethoxy)ethanol |
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4. Ethylene glycol |
9. 2-(2-Butoxyethoxy)ethanol |
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5. Ethyl-3-ethoxy propionate |
10. Monoethanolamine |
1990 [3] (Critical temperature, pressure, density)
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1. n-Hexanal (Tc, dc) |
5. n-Decanal (Tc, dc) |
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2. n-Heptanal (Tc, Pc, dc) |
6. Tetralin (Tc, Pc) |
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3. n-Octanal (Tc, dc) |
7. N-Methylpyrrolidone (Tc, Pc) |
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4. n-Nonanal (Tc, Pc, dc) |
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1991 [3] (Critical temperature, density)
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1. 2-Hexanone |
7. 3-Octanone |
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2. 3-Hexanone |
8. 4-Octanone |
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3. 2-Heptanone |
9. 2-Nonanone |
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4. 3-Heptanone |
10. 3-Nonanone |
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5. 4-Heptanone |
11. 4-Nonanone |
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6. 2-Octanone |
12. 5-Nonanone |
1992 [4] (Critical temperature, pressure and volume)
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1. 2-Hexanone |
7. tert-Amylmethyl Ether |
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2. 2-Heptanone |
8. Ethyl tert-Butyl Ether |
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3. Cumene |
9. Isopropyl Acetate (Tc, dc) |
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4. Ethylbenzene |
10. 2-Pentanone |
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5. Toluene |
11. Hexafluoroethane |
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6. Propene |
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1993 [5] (Critical temperature, pressure and volume)
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1. Acrylonitrile |
6. 2-Methoxyethanol |
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2. Cyclohexanol |
7. 2-(2-Methoxyethoxy)ethanol |
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3. Ethyl Thioacetate |
8. y -Butyrolactone |
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4. 2-(2-Ethoxyethoxy)ethanol |
9. 2-Nonanone |
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5. Methoxy benzene (Anisole) |
10. Isopropyl Acetate (Pc) |
1994 [5] (Critical temperature, pressure and volume)
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1. 1,4-Butanediol |
4. 1,2-Ethanediamine |
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2. 2-(2-Butoxyethoxy)ethyl Acetate |
5. 1-Methoxy-2-propanol |
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3. 2-(2-Ethoxyethoxy)ethyl Acetate |
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1995 [6] (Critical temperature and pressure)
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1. 1-Butoxy-2-propanol |
5. 2-Methyl-1,3-propanediol |
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2. Di-(2-aminoethyl)amine |
6. 1,2-Propanediol |
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3. Diethyl Sulfide |
7. Propylene Carbonate |
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4. 1,2-Ethanediol |
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1996 [6] (Critical temperature and pressure)
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1. Acetonitrile |
5. s-Phenylethyl Alcohol |
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2. 1-n-Propoxy-2-propanol |
6. N-(2-Aminoethyl) |
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3. 1-t-Butoxy-2-propanol |
7. 1,3-Propanediol |
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4. 1-Dodecanethiol |
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1997 [7] (Critical temperature and pressure)
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1. Toluene* |
8. Propylene carbonate |
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2. 2-(2-amino ethylamino)ethanol |
9. 1,4-butanediol |
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3. 1,3-propanediol |
10. DEG ethyl ether acetate |
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4. 2-methyl-1,3-propanediol |
11. Ethylbenzene* |
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5. 2-(2-butoxy ethoxy)ethyl acetate |
12. Phenyl acetate |
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6. Styrene* |
13. Squalane* |
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7. Diethylene triamine |
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* These compounds were for a special study undertaken by the investigator.
1998 [8] (Critical temperature and pressure)
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1. Triacontane ( Extrapolated) |
5. 2-Phenylethanol |
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2. Dodecanethiol |
6. Acrylamide (not done, may be for another investigator) |
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3. Thioanisole |
7. 1-t-butoxy-2-propanol |
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4. Allyl Alcohol |
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1999 [9] (Critical temperature and pressure)
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1. Dibutyl Disulfide (Extrapolated) |
6. Dipropylene glycol |
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2. 1,2-epoxy-2-methylpropane |
7. Diethyl oxalate* |
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3. N-methyldiethanolamine |
8. n butyl acrylate* |
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4. 1,3-butanediol |
9. 4-formylmorpholine* |
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5. gamma-butyrolactone |
10. Napthalene* |
* compounds selected by the project investigator
2000 [9] (Critical temperature and pressure)
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1. Alkanoic acids with 2,6,8,11,12,14,15,16,17,20,22 carbons (Dr. Nikitin's work) |
6. Dimethyl disulfide |
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2. 2-(2-aminoethoxy)ethanol |
7. Oxazole |
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3. t-butyl acetate |
8. Phenyl iscoyanate |
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4. 1,1-ethanediol diacetate |
9. Sulfolane (Extraplated) |
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5. p-diisopropylbenzene |
2001 [10] (Critical temperature and pressure)
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1. 1,6-hexanediol |
3. 1,3-benzenediol |
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2. 1,2-benzenediol |
4. Piperazine |
2002 [P] (Critical temperature and pressure)
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1. 2,4,4-trimethyl-1-pentene |
4. Dimethyl terphthalate (approximate) |
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2. p-tolualdehyde |
5. N-methylacetamide |
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3. Bisphenol A (not done) |
6. Diphenylmethane |
2003 [P] (Critical temperature and pressure)
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1. Dimethyl carbonate |
4. 3-methylthiophene |
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2. Methoxyacetone |
5. 2-phenoxyethanol |
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3. 2-methylthiophene |
2004 [P] (Critical temperature and pressure)
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1. 2-methylpropanal |
8. Benzaldehyde |
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2. 2-methoxy-1-propanol |
9. p-tolualdehyde |
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3. 2-ethoxyethanol |
10. Benzyl alcohol |
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4. Tetrahydrothiopene |
11. p-tolualcohol |
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5. Methyl acetoacetate |
12 Benzoic acid |
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6. Ethylene glycol diacetate |
13. p-toluic acid |
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7. Phenyl mercaptan |
Published Results:
[1] 1985-1988 project results have been published in the AIChE Symposium Series,vol. 86, no. 275 (1990).
[2] 1989 project results have been published in the AIChE DIPPR Data Series, No. 1 (1991).
[3] 1990-91 project results were published in the AIChE DIPPR Data Series, No. 2 (1994).
[4] 1992 project results were published in J.Chem.Eng. Data 40 (4), 765-768 (1995).
[5] 1993 and 1994 project results will be published in J Chem Eng Data 41 (6), 1252-1254 (Nov./Dec., 1996).
Note: Three compounds were too reactive to permit accurate measurements: 1,4-dichloro-butane; 2-(2-aminoethylamino)ethanol; phenyl acetate.
[6] 1995 and 1996 projects were published in J.Chem.Eng. Data 45 (2), 154-156 (2000).
[7] 1997 projects were published in J.Chem.Eng. Data 47 (4), 761-764 (2002).
[8] 1998 results were published in J.Chem.Eng. Data 51 (6), 1982-1985 (2006).
[9] 1999 and 2000 results were published in J.Chem.Eng. Data 51 (6), 1990-1995 (2006).
[10] 2001 results were published in J.Chem.Eng. Data 51 (6), 1986-1989 (2006).
Pending Publication:
2002, 2003 and 2004 results have been approved for publication.