Enthalpies of Vaporization of Organic and Organometallic Compounds, 1880–2002
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Enthalpies of Vaporization of Organic and Organometallic Compounds, 1880–2002 James S. Chickosa… Department of Chemistry, University of Missouri-St. Louis, St. Louis, Missouri 63121 William E. Acree, Jr.b… Department of Chemistry, University of North Texas, Denton, Texas 76203 ͑Received 17 June 2002; accepted 17 October 2002; published 21 April 2003͒ A compendium of vaporization enthalpies published within the period 1910–2002 is reported. A brief review of temperature adjustments of vaporization enthalpies from temperature of measurement to the standard reference temperature, 298.15 K, is included as are recently suggested reference materials. Vaporization enthalpies are included for organic, organo-metallic, and a few inorganic compounds. This compendium is the third in a series focusing on phase change enthalpies. Previous compendia focused on fusion and sublimation enthalpies. Sufficient data are presently available for many compounds that thermodynamic cycles can be constructed to evaluate the reliability of the measure- ments. A protocol for doing so is described. © 2003 American Institute of Physics. ͓DOI: 10.1063/1.1529214͔ Key words: compendium; enthalpies of condensation; evaporation; organic compounds; vaporization enthalpy. Contents inorganic compounds, 1880–2002. ............. 820 1. Introduction................................ 519 8. References to Tables 6 and 7.................. 853 2. Reference Materials for Vaporization Enthalpy Measurements.............................. 520 List of Figures 3. Heat Capacity Adjustments. ................. 520 1. A thermodynamic cycle for adjusting vaporization ϭ 4. Group Additivity Values for C (298.15 K) enthalpies to T 298.15 K.................... 521 pl 2. A hypothetical molecule illustrating the different Estimations................................ 521 hydrocarbon groups in estimating C ........... 523 5. A Thermochemical Cycle: Sublimation, p Vaporization, and Fusion Enthalpies............ 523 6. Estimation of Vaporization Enthalpies. ......... 525 1. Introduction 7. Vaporization Enthalpy Compendium. .......... 525 8. Acknowledgment........................... 878 Vaporization enthalpies are important thermodynamic 9. References for Introductory Material. ......... 878 properties of the condensed phase. Vaporization enthalpies are used frequently in adjusting enthalpies of formation of List of Tables liquids to the standard state and in evaluating environmental 1. Recommended reference standards for transport properties.1,2 To the chemical engineer, the magni- vaporization enthalpy measurements............ 520 tude of this property needs to be taken into consideration in ⌫ ⌫ 2. Group values l and c for estimating designing equipment for chemical processing and synthesis. C (298.15 K) and C (298.15 K)............. pl pc 522 Thus vaporization enthalpy data are of interest at a variety of 3. Some estimations of C (298.15 K) and temperatures. As a consequence, there is a wealth of infor- pl C (298.15 K) using group values. ........... mation in the literature that covers measurements over a pc 524 4. A comparison of experimental sublimation broad range of temperatures. The data covered by this com- enthalpies and those calculated using Eq. ͑6͒..... 525 pendium include as much of the spectrum as was available to 5. A list of acronyms used in Tables 6 and 7....... 526 us. 6. Enthalpies of vaporization of organic compounds, Our interest in vaporization enthalpies goes back nearly 1880–2002................................ 527 two decades. Our primary focus in measuring vaporization 7. Enthalpies of vaporization of organometallic and enthalpies was as a means of adjusting enthalpies of forma- tion of liquids to the standard state and in conjunction with fusion enthalpies to adjust solids in a similar fashion.3 Since a͒ Author to whom correspondence should be addressed; electronic mail: then we have focused our attention on their estimation,4 and [email protected] 5 b͒Electronic mail: [email protected] assessment. In parallel studies, compilations of available 6,7 © 2003 American Institute of Physics. sublimation and fusion enthalpies were also initiated. A Õ Õ Õ Õ Õ 0047-2689 2003 32„2… 519 360 $37.50519 J. Phys. Chem. Ref. Data, Vol. 32, No. 2, 2003 520 J. S. CHICKOS AND W. E. ACREE, JR. TABLE 1. Recommended reference standards for vaporization enthalpy measurements ⌬ ͑ ͒ Ϫ1 Substance T/K range Vapor pressure range/Pa vapHm 298.15 K kJ mol Classification a,d ϩ ϩ Ϯ C3H8O 1-propanol 333–378 20 E 3–135 E 3 47.45 0.1 Primary b,d ϩ ϩ Ϯ C5H12 pentane 269–315 2.0 E 4–1.2 E 5 26.42 0.1 Primary a,d ϩ ϩ Ϯ C6F6 hexafluorobenzene 290–377 7.5 E 3–2.1 E 5 35.71 0.07 Primary a,c,d ϩ ϩ Ϯ C6H6 benzene 286–383 7.0 E 3–2.3 E 5 33.83 0.07 Primary b,d ϩ ϩ Ϯ C6H14 hexane 286–343 1.2 E 4–1.0 E 5 31.52 0.13 Primary b,d ϩ ϩ Ϯ C7H16 heptane 299–372 6.4 E 3–1.0 E 5 36.57 0.15 Primary b,d ϩ ϩ Ϯ C8H18 octane 326–400 7.7 E 3–1.0 E 5 41.56 0.17 Primary b,d ϩ ϩ Ϯ C9H20 nonane 344–425 6.4 E 3–1.0 E 5 46.55 0.19 Primary d ϩ ϩ Ϯ C10H8 naphthalene 353–434 1.0 E 3–2.3 E 4 55.65 2.8 Secondary b,d ϩ ϩ Ϯ C10H22 decane 268–348 1.7 E 1–3.2 E 3 51.42 0.21 Primary b,d ϩ ϩ Ϯ C11H24 undecane 294–382 4.1 E 1–6.4 E 3 56.58 0.57 Primary b,d ϩ ϩ Ϯ C12H26 dodecane 313–403 5.8 E 1–7.3 E 3 61.52 0.62 Primary b,d ϩ ϩ Ϯ C13H28 tridecane 323–402 4.7 E 1–3.7 E 3 66.68 0.67 Primary b,d ϩ ϩ Ϯ C14H30 tetradecane 344–422 7.6 E 1–4.4 E 3 71.73 0.72 Primary b,d ϩ ϩ Ϯ C16H32 hexadecane 364–452 5.5 E 1–4.7 E 3 81.35 0.81 Primary b,d Ϫ ϩ Ϯ C18H38 octadecane 312–590 1.0 E 1–1.0 E 5 91.44 1.83 Primary b,d Ϫ ϩ Ϯ C20H42 eicosane 344–380 4.1 E 1–9.1 E 0 101.81 2.0 Primary d ϩ ϩ Ϯ H2O water 273–373 6.1 E 1–1.0 E 5 43.99 0.07 Primary aReference 12. bReference 13. cCancer suspect agent. dReference 5. reasonably exhaustive version of these databases covering in Table 1. The temperature range, the corresponding vapor the literature to the present has recently been published and pressures, and the recommended molar vaporization enthal- is also available on line at http://webbook.nist.gov/ pies at Tϭ298.15 K are also included in the table. Some of chemistry/. Combined with fusion and sublimation enthalp- these reference materials are solids at Tϭ298.15 K and ies appropriately adjusted to Tϭ298.15 K, vaporization en- therefore the vaporization enthalpies are hypothetical values. ⌬ thalpies vapHm (298.15 K), complete a thermochemical The reader should consult the literature cited at the bottom of cycle that can be used to assess the quality of the available the table to obtain the vaporization enthalpy at the tempera- data. Application of this thermochemical cycle is illustrated ture of interest. below. A goal of the present contribution has been to provide an exhaustive coverage of the literature from about 1880 to 2002; regrettably however, this compilation is probably still 3. Heat Capacity Adjustments incomplete. Vaporization enthalpies, like their sublimation counter- 2. Reference Materials for Vaporization parts, are measurements based on mass transport and as such Enthalpy Measurements are directly or indirectly dependent upon vapor pressure. The vapor pressure of different liquids at a given temperature can Calibration is a fundamental requirement in every thermo- vary many orders of magnitude. In order to obtain a reason- chemical measurement of vaporization enthalpy. Regardless able amount of mass transport, it is frequently necessary to of which technique is used, the measurement ultimately de- conduct these measurements at temperatures that differ sub- pends either directly or indirectly on vapor pressure. Vapor stantially from the standard reference temperature, 298.15 K. pressures of liquids vary over many orders of magnitude. An The actual temperature of measurement depends on the sen- experimental technique calibrated with a standard in one sitivity of the instrument or apparatus and the properties of pressure or temperature regime does not in itself guarantee the substance of interest. Vaporization enthalpy measure- the same accuracy in another. Substantial variations in vapor- ments are often conducted as a function of temperature. ization enthalpy are revealed in the tables that follow. This The magnitude of the vaporization enthalpy is dependent variance clearly establishes the importance of documenting on temperature. Figure 1 and Eqs. ͑1͒ and ͑2͒ illustrate the the accuracy of the measurements through the use of appro- origin of this temperature dependence in terms of a thermo- priate reference materials that approximate the temperature dynamic cycle. If the heat capacities of the liquid and gas phase are known, C and C , respectively, then the vapor- and pressure regimes of the measurements of interest. pl pg A series of compounds have been recently proposed as ization enthalpy at Tϭ298.15 K can be related to the experi- reference materials for vaporization enthalpy.5 These have mental measurements by using Eq. ͑1͒. This equation, gen- been classified as primary, secondary, or tertiary reference erally referred to as Kirchhoff’s equation, can be used to materials, on the basis of various criteria. The materials clas- adjust sublimation enthalpy measurements to any reference sified as primary and secondary reference materials are listed temperature. The term Tm represents either the temperature J. Phys. Chem. Ref. Data, Vol.