vapor pressure and antoine constants for hydrocarbons, springer (1999),

Landolt-Börnstein
Numerical Data and Functional Relationships in Science and Technology
New Series
/ Editor in Chief: W. Martienssen
Group IV: Physical Chemistry
Volume 20
Vapor Pressure of Chemicals
Subvolume A
Vapor Pressure and Antoine Constants for Hydrocarbons, and
Sulfur, Selenium, Tellurium, and Halogen Containing Organic Compounds
J. Dykyj, J. Svoboda, R.C. Wilhoit, M. Frenkel, K.R. Hall
Edited by K.R. Hall
12 3
ISSN 0942-7996 (Physical Chemistry)
ISBN 3-540-64735-X Springer-Verlag Berlin Heidelberg New York
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Tables chiefly in English.
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1. Physics Tables. 2. Chemistry Tables. 3. Engineering Tables.
I. Börnstein, R. (Richard), 1852-1913. II. Landolt, H. (Hans), 1831-1910.
III. Physikalisch-chemische Tabellen. IV. Title: Numerical data and functional relationships in science and technology.
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Editor
K.R. Hall
Thermodynamics Research Center
TheTexas A&M University System
College Station, Texas 77843-3111, USA
Authors
J. Dykyj
J. Svoboda
R.C. Wilhoit
M. Frenkel
K.R. Hall
Thermodynamics Research Center
TheTexas A&M University System

College Station, Texas 77843-3111, USA
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Preface
The thermodynamic properties of fluids are vital information for design, operation (including safety
considerations) and maintenance in the fluid processing or continuous manufacturing industries. Among
the thermodynamic properties, some are more important and pervasive with vapor pressure being possibly
the most important of all. Practical handling of any fluid requires knowledge of its vapor pressure, and
vapor pressure (or boiling point) is invariably among the first properties measured for any substance.
Chemists and chemical engineers are the primary people who need these data. Traditionally, these
professionals have populated the petrochemical industries and have driven it to unparalleled levels of
efficiency and productivity. However, these same professionals recently have migrated into other fields,
such as: electronic materials, pharmaceuticals, environmental professions, food processing, and
biotechnology. They bring with them their skills and knowledge of continuous processing and their
consequent need for thermodynamic properties, such as vapor pressure. In addition, the faculty and
students of academia need this information to prepare those who would enter the fluid processing
industries.
The Thermodynamics Research Center at Texas A&M University (TRC) has assembled, collected,
evaluated and published tables of thermodynamic data for nearly 60 years. These current volumes
describing vapor pressures come from those tables and other evaluation projects conducted by TRC and
other research groups, and, as of the publication date, represent all known, evaluated data. The volumes
contain constants derived from fitting experimental data with the Antoine and extended Antoine vapor
pressure equations. The condensed phases can be either liquid or crystal. Thus, these constants provide
evaluated vapor pressures which professional thermodynamicists believe represent the data within

experimental error.
The present volume covers hydrocarbons and organic chemicals containing S, Se, Te as well as
halohydrocarbons, total of 4,252 compounds.
While the parameters presented in this series only describe pure compounds, the vapor pressures of
pure compounds are essential for describing the phase behavior of mixtures accurately. The simplest
equation for describing the phase behavior of mixtures is Raoult’s Law which states that the mole fraction
of a component in an equilibrium vapor mixture multiplied by the total pressure equals the mole fraction
of that component in the equilibrium liquid mixture multiplied by the vapor pressure. More accurate
equations append correction terms to each side of this equation.
Because these volumes present vapor pressures for such a wide variety of organic compounds, they
should be of value to professionals in a wide variety of commercial and academic activities. Because they
have been evaluated, those who would use these values are freed from the necessity of selecting from
among various sets of data.
College Station, Texas, January 1999 The Editor
Acknowledgements
The authors express their sincere thanks to members of the staff of the Thermodynamics Research Center,
part of the Chemical Engineering Division of the Texas Engineering Experiment Station within the Texas
A&M University System. Our special thanks to Colin Worthy, Christina Virgilio, James Requenez, Munaf
Chasmawala, and Cheryl Clark, and for their assistance in data collection and entry, formatting the text,
and composing the camera-ready copy of the manuscript.
College Station, Texas, January 1999 J. Dykyj, J. Svoboda, R.C. Wilhoit, M. Frenkel, K.R. Hall
Ref. p. 12] 1 Introduction
Landolt-Börnstein
New Series IV/20A
1
1 Introduction
1.1 Definitions
Equilibrium intensive thermodynamic properties of pure compounds that exist as a single phase,
e.g.
crystal (solid), liquid or gas, are functions of two independent observables. Temperature and pressure are

usually the selected variables, although other pairs may be used.
Properties of pure compounds that exist as two phases in equilibrium are functions of one independent
variable. Either temperature or pressure may be chosen as the independent variable. If one of the phases is
condensed (solid or liquid) and the other phase is gas (vapor) and temperature is the independent variable,
the pressure is the
vapor pressure
. The vapor pressure is a function only of temperature, and it is
independent of the volume of the system or of the amounts of phases present. If pressure is the
independent variable, the temperature is the
boiling point
. Therefore, the boiling point is a function only
of pressure applied to the system and is independent of the total volume or of the amounts of the two
phases present
The terms
vapor pressure
and
boiling point
of a pure component are two equivalent ways of referring
to the same physical state. When the condensed phase is a solid the term
sublimation point
is usually used
instead of
boiling point
. The boiling (or sublimation) point at one atmosphere is the
normal boiling
(sublimation) point.
Reciprocal temperature in thermodynamics is the integrating factor for reversible energy transfer as
heat. Two kinds of temperature exist:
thermodynamic temperature
that is independent of any particular

physical system and defined within the Second Law of Thermodynamics and the
practical temperature
scale
used with thermometers
.
The International Committee on Weights and Measures establishes this
scale and keeps it as consistent as possible with the thermodynamic temperature. The ITS (International
Temperature Scale) is revised every 20 years (most recently in 1990). Temperatures measured on this
scale are designated ITS-90. The size of the degree on this scale is determined by the convention that the
triple point of water is exactly 273.16 K on the ITS-90 scale. The rest of the scale is defined in terms of
18
fixed points
consisting of melting and boiling points of specified substances. Exact temperatures are
assigned to these points. Interpolation between points is made by a series of standard thermometers whose
construction is specified in the definition of ITS-90 [90-its]
Pressure is the force per unit area acting perpendicular to a surface. The unit of pressure in the SI
system of units is Newtons per square meter. This unit is also called the
Pascal
and abbreviated as Pa.
Another unit frequently encountered in practice is the
torr
. This unit corresponds to a millimeter of
mercury in a standard barometer. The standard barometer is a glass tube filled with mercury connected to
vacuum on one side and to the measured pressure on the other. The mercury is at 0
o
C in a location having
gravity corresponding to the standard gravitational acceleration,
g
= 9.807 m
⋅

s
–2
. One atmosphere (1 atm)
is 760 torr exactly, which corresponds to 101325 Pa.
The highest temperature at which a liquid can exist in equilibrium with its vapor is the
critical
temperature
. Above this temperature liquid and vapor do not exist as separate phases. Thus, a substance
does not have a vapor pressure (or boiling point) above its critical temperature. The pressure exerted by a
substance at its critical temperature is its
critical pressure
and the density in this state is the
critical
density
. Critical constants are significant not only because they provide the upper limit of vapor pressure,
1 Introduction [Ref. p. 12
Landolt-Börnstein
New Series IV/20A
2
but also because of their theoretical implications, their use in developing equations of state and the role
they play in many physicochemical correlations. A recent compilation of recommended critical constants
is being published as a series [95-ambyou, 95-ambtso, 95-tsoamb, 95-gudtej, 96-dau].
1.2 Measurement of Vapor Pressure and Boiling (or Sublimation)
Point
The experimental determination of a vapor pressure or boiling (sublimation) point for a pure compound
using static or quasistatic methods consists of measuring the temperature and pressure of a sample of the
compound when a condensed phase exists in equilibrium with the gas phase. Temperature is measured
with a thermometer. Examples of thermometers are mercury-in-glass thermometers, thermocouples,
electrical resistance thermometers, thermistors, quartz crystal oscillators, and optical pyrometers [82-
guahon]. Pressure usually is measured with a manometer, mercury barometer, Bourdon gage or dead-

weight gage. The choice of instrument depends upon the accuracy desired and the range of temperatures
and pressures, among other considerations.
Manometers are used in two general ways. The manometer may be placed in direct contact with the
system at equilibrium, usually in contact with the vapor phase. When used this way, the manometer must
be kept at a temperature equal to or greater than that of the system. The other technique uses a pressure
transducer. A pressure transducer compares the two pressures on either side of the transducer. It responds
when the two pressures are equal. One side of the transducer contacts the system and the other side
contacts an external fluid (usually a gas) that contacts the manometer. The external pressure is adjusted to
equal the system pressure, and then the manometer reads the system pressure. In this technique, the
manometer can be maintained at any convenient temperature.
A pressure transducer may consist of no more than a simple U-shaped glass tube containing an inert
liquid such as mercury. Pressure equality occurs when the liquid is at the same level in both legs of the
tube. However, pressure transducers also may be elaborate instruments based upon detecting the
movement of some type of diaphragm.
Besides the thermometer and pressure gauge, the experimental apparatus requires a means to hold the
two phases at equilibrium in close contact long enough for the pressure and temperature to be measured.
The thermometer and pressure gauge must respond to the temperature and pressure existing at phase
equilibrium. Finally, the measurement requires using a sample of sufficient purity.
Errors in measurement arise from calibration and reading of the thermometer and pressure gauge,
inappropriate placement of the sensors of these instruments, failure to achieve equilibrium and impurities
in the sample. Impurities may be present in the original sample or may arise from decomposition of the
sample or other chemical changes that occur during the course of the measurement.
Two experimental techniques are used for vapor pressure measurements. In one, the sample is
contained in a constant temperature environment (thermostat). When the pressure reaches its equilibrium
value, the observed value at the established temperature is the vapor pressure. With the other technique,
the sample is maintained at a fixed pressure using a manostat and the system is allowed to reach its
equilibrium temperature. The observed temperature at this pressure is the boiling point.
Experimental techniques may be somewhat arbitrarily classified as static, quasistatic (also called
dynamic), and kinetic. [51-par, 93-fre]
Ref. p. 12] 1 Introduction

Landolt-Börnstein
New Series IV/20A
3
1.2.1 Static Techniques
1.2.1.1 Direct Sealed Container
Conceptually, this is the simplest type of vapor pressure apparatus. The sample is placed in a closed
container and all air and other volatile impurities are removed as completely as possible. The container is
placed in a thermostat kept at constant temperature until phase equilibrium occurs. The temperature and
pressure are measured. The pressure gauge can be connected to the system directly or through a pressure
transducer.
The main drawback with this technique is the difficulty associated with removing volatile impurities,
which involves a sequence of freeze-thaw cycles of the sample under high vacuum. This procedure
becomes more difficult to implement for systems having low vapor pressures because the effects of
volatile impurities become greater. The procedure also is sensitive to sample decomposition because
decomposition products are usually volatile. The lower limit of usefulness is around 100 Pa.
The direct sealed container technique is used more often for mixtures than for pure substances. The
possibility of preparing mixtures of accurately known composition compensates for the difficulty in
removing volatile impurities.
1.2.1.2 The Isoteniscope
Smith and Menzies [10-smimen] first describe the isoteniscope. This instrument operates as a special type
of static method using a glass U-tube as a pressure transducer. Generally, the apparatus includes a sample
bulb made from glass for visibility. The U-tube may contain mercury but is more likely to contain the
liquid phase of the sample being measured. The apparatus usually is placed in a thermostat and the
external pressure is adjusted to equal that of the vapor in contact with the sample. The advantage of this
technique is that, when the external pressure is lowered, the sample vapor can bubble through the U-tube,
which assists in removing volatile impurities. This sample purging is repeated until constant pressure
readings are attained. This procedure is also valid for samples that undergo slow decomposition. The
accuracy of this method is limited by the sensitivity of the pressure transducer, in normal use about 20 Pa.
1.2.1.3 The Inclined Piston Gage
This device employs another variation of the static method. The sample is placed in a cylinder closed at

the bottom and fitted with a freely moveable piston at the top. The pressure of the gas sample balances the
weight of the piston. The effective weight of the piston can be adjusted by tilting the cylinder from a
vertical position. The pressure can be calculated from the tilt angle when the sample pressure balances the
piston weight. Although it is difficult to remove volatile impurities, this method provides the most
accurate measurements made in the range of 100 to 1500 Pa. It is applicable to solids as well as liquids.
1.2.2 Quasistatic Techniques
In quasistatic (or dynamic) techniques, a steady rate of boiling or evaporation is established, and it is
assumed that the pressure attained in this steady state is the same as the equilibrium pressure. In careful
experiments, pressures are measured at several evaporation rates to verify that they do not depend upon
the rate within the experimental conditions.
1.2.2.1 Ebulliometric Techniques
Construction details vary considerably for these devices. In all cases, liquid boils when subjected to steady
heating. The vapor passes through a reflux condenser and the resulting liquid returns to the boiler, thus
1 Introduction [Ref. p. 12
Landolt-Börnstein
New Series IV/20A
4
achieving a steady cycle. Generally, a constant pressure is maintained at the top of the condenser and the
temperature of the boiling liquid and vapor is measured. This temperature is the boiling point.
An advantage of this technique is that volatile impurities, especially air, that do not condense in the
condenser are removed at the top of the device. The chief limitations are difficulties in attaining smooth,
steady boiling without superheating the liquid and in locating the thermometer such that it records to the
equilibrium temperature. Special pumps that spray the thermometer with a mixture of liquid and vapor
exist. Difficulties in reaching steady boiling limit this technique to pressures greater than 1000 Pa (greater
for some substances).
Crude measurements are easy to perform with this technique. With careful attention to details,
however it is possible to make the most accurate measurements over the range of 2000 to 200,000 Pa
using ebulliometers. With high quality samples, boiling point accuracy of 0.01
o
C or better is possible.

A variation on this technique is twin ebulliometers. In this technique, two matched ebulliometers are
connected to the same external pressure at the top of the condenser. A standard substance with accurately
known vapor pressure is placed in one ebulliometer and the test sample in the other. When steady boiling
is attained in both sides, they are at the same pressure. Pressure is not measured directly; rather the two
boiling temperatures are measured. Pressure is established by converting the boiling point of the standard
to pressure using a previously determined relationship. For organic liquids, water, benzene, or decane are
often used as standards.
Diverting some of the liquid from the condenser enables a sample distillation. For a pure sample, the
observed boiling point should not change as the distillation proceeds. Any change in boiling temperature
is a measure of sample purity.
This method also produces vapor-liquid equilibrium data for mixtures. It is restricted to liquid samples,
however.
1.2.2.2 Transpiration Technique
In this method, a steady stream of inert gas passes over or through the sample held at a constant
temperature. The concentration of the sample in the emerging stream is measured. This concentration is
then converted to partial pressure, usually by assuming an ideal gas mixture. This partial pressure is the
vapor pressure. The method is applicable for solid or liquid samples.
The accuracy of this technique is limited by the difficulty in maintaining steady gas flow, in achieving
a sample concentration corresponding to equilibrium without entrainment of liquid drops or solid dust
particles, and in analyzing the gas stream. Analysis sometimes employs condensing the sample in a cold
trap, and sometimes using some type of chemical analysis. Occasionally, data of high accuracy results
from this method, but usually they range from 0.5 to 5%. This method is most useful over the range 100 to
5000 Pa. Its sensitivity to impurities depends upon the method of analysis.
1.2.3 Kinetic Methods
In kinetic methods, a steady rate of evaporation, not necessarily close to equilibrium, is established and
measured. Temperature is constant but pressure is not measured directly. Rather, pressure is calculated
from the evaporation rate using kinetic theories. Accuracies are low using such methods. The techniques
are used exclusively for pressures below about 100 Pa where other methods are not applicable. Even when
kinetic methods do not yield meaningful absolute pressures, they may produce a temperature derivative of
pressure that can provide the enthalpy of vaporization using Eq. (1.1).

1.2.3.1 Knudsen Effusion Method
In this method, the sample is placed in a small heated chamber with a small hole in either a side or the top.
The chamber is placed in a continuously pumped, high vacuum environment. As the sample evaporates
gas effuses through the hole into the external vacuum. The flow rate of gas though the hole is a function of
Ref. p. 12] 1 Introduction
Landolt-Börnstein
New Series IV/20A
5
internal pressure, temperature, and the diameter and length of the hole. Under ideal conditions, kinetic
theory provides this flow rate (see [93-fre] for this derivation). Measurement of the sample weight loss
during evaporation at constant temperature provides the rate of evaporation. Using a continuous weighing
technique that does not require removal of the sample chamber greatly increases the speed of making
measurements. One method consists of suspending the sample chamber from a quartz spiral spring and
measuring its change in length as the sample evaporates. However, temperature measurement is difficult
using this technique.
1.2.3.2 Langmuir Method
In this method, the rate of evaporation from an open surface directly into a vacuum is measured. This rate
bears some relation to vapor pressure, but it also depends in complicated way upon many other variables.
Among these variables are the effective surface area and the coefficient of vaporization. A discussion
appears in [93-fre]. This method is confined almost exclusively to solids, and the magnitude of the
pressure is subject to large errors.
1.2.4 Measurement of Critical Constants
Special techniques have been developed to measure critical temperature, pressure and density. The most
common manner to observe the critical temperature is to heat a sample in a closed tube and measure the
temperature at which the boundary (meniscus) between liquid and vapor disappears. This method
produces an accuracy of about 0.5 degree in most cases. More sophisticated methods for detecting the
merging of the two phases are available, but achieving a reproducibility of better that 0.1 degree is
difficult. Some properties of a substance change rapidly in the vicinity of the critical point and many
organic compounds decompose at or below the critical temperature. Rapid methods of observation have
been developed for these compounds.

The force of gravity influences the measurement of critical temperature. Some have suggested that
accurate measurements of the critical temperature must be made in the absence of gravity, such as in an
orbiting satellite. This experiment has not yet been performed.
Given the critical temperature of a substance, the critical pressure can be obtained by measuring the
pressure at that temperature. It is more common to measure the vapor pressure over a range near the
critical temperature, and then to extrapolate to the critical temperature.
1 Introduction [Ref. p. 12
Landolt-Börnstein
New Series IV/20A
6
1.3 Mathematical Representation of Vapor Pressure
1.3.1 Thermodynamic Relationships
A consequence of the second law of thermodynamics is that the chemical potential of any component in
equilibrium phases at a particular temperature or pressure is the same in all phases. For a pure compound
the chemical potential is the Gibbs energy per mole of the substance. The following equation results for a
condensed phase in equilibrium with the gas phase.
dP/dT = (∆
v
H

)(∆
v
V)
–1
T
–1
(1.1)
In this equation ∆
v
H is the molar change in enthalpy for the conversion of substance from the equilibrium

liquid to the equilibrium vapor phase. ∆
v
V is the molar change in volume when the substance changes
from the liquid to the gas. This equation allows calculation of the enthalpy of vaporization from vapor
pressure, and it is the second law method. Measurement of enthalpy of vaporization with a calorimeter is
the first law method. The quantities ∆
v
H and ∆
v
V are functions of temperature along the phase boundary.
Equation (1.1) can also be written as,
d(ln P)/dT = (∆
v
H)(∆
v
Z
–1
) R
–1
T
–2
(1.2)
where Z is the compression factor (Z = PV/RT). At temperatures well below the critical temperature, the
liquid volume is negligible compared to the gas volume. If, furthermore, the gas is ideal, then ∆
v
Z is 1.0
and Eq. (1.2) becomes,
d(ln P)/dT = (∆
v
H)R

–1
T
–2
(1.3)
known as the Clausius-Clapyron equation. The total derivative of ∆
v
H along the boundary is a function of
heat capacities and volumes,
d(∆
v
H)/dT = ∆
v
C
p
+ ∆
v
V – T(∂∆
v
V/∂T)
p
(1.4)
If the functional forms of the heat capacities and volumes of the phases are known, they can be substituted
into Eqs. (1.2) and (1.4) and upon integration provide an accurate, functional representation of the vapor pressure:
()()
[]
11
1
0
0
lnln

−−
−
∫
∆∆+=
dTRZHPP
T
T
VV
(1.5)
Here, P
0
is the pressure at some reference temperature, T
0
. However, it is rare that the functions are known
sufficiently well to derive an accurate vapor pressure equation in this way (see [82-mos/van, 96-ruzmaj]
for a more complete thermodynamic analysis of vapor pressure).
More approximate vapor pressure equations result from making various assumptions and
simplifications. For example, the terms ∆
v
V – T(∂∆
v
V/∂T) nearly cancel at temperatures well below the
critical temperature. At these temperatures the liquid volume is much smaller than the gas volume and can
be neglected. Neglecting these terms, assuming the gas phase is ideal, and assuming ∆
v
C
p
is constant, Eq.
(1.5) becomes
ln P = ln P

0
– [∆
v
C
p
(1 + ln T
0
) + ((∆
v
H
0
)T
0
-1
– (∆
v
H
0
)

+ T
0
)(∆
v
C
p
)(T)
–1
) + (∆
v

C
p
) ln T]R
–1
(1.6)
If ∆
v
C
p
is zero, Eq. (1.6) becomes,
ln P = a + bT
–1
(1.7)
where a and b are constants. Equation (1.7) is used often to represent approximate vapor pressure data,
especially for low pressures where experimental data are seldom accurate.
Ref. p. 12] 1 Introduction
Landolt-Börnstein
New Series IV/20A
7
1.3.2 Empirical Vapor Pressure Equations
During the past century many empirical mathematical functions have been used to relate vapor pressure to
temperature; most are modifications of Eq. (1.7). These functions have several parameters that are
characteristic of the compound. Curve fits off experimental data, usually by minimizing the sum of the
squares of the deviations between the calculated and observed pressures or temperatures (least squares
criterion), provide these parameters. The first and most widely used of these equations is the Antoine
equation [1888-ant, 46-tho]. The original form is,
log P = A – B (C + T)
–1
(1.8)
Sometimes the natural logarithm is used instead of the base-10 logarithm or Celsius temperature is used

instead of Kelvin. When C = 0 (for T in kelvins) Eq. (1.8) is identical to Eq. (1.7). The Thermodynamics
Research Center Thermodynamic Tables - Hydrocarbons [xx-trchc] and Nonhydrocarbons [xx-trcnh] -
use an extended version of the Antoine equation:
log P = A – B (C + T)
-1
+ 0.43429
χ
n
+ E
χ
8
+ F
χ
12
(1.9)
where n, E, and F are additional adjustable parameters. T
c
is the critical temperature, T
0
the lower
boundary temperature and
χ
= (T – T
0
)/T
c
Examples of functions obtained by adding terms to Eq. (1.7) are the polynomial in temperature used in the
International Critical Tables [26-ano],
ln P = A + BT
-1

+ CT + DT
2
, (1.10)
the Chebyshev polynomial [70-ambcou]
TPa a E ()
ss
i
ln /
=+
=
∑
0
2
χ
s1
(1.11)
χ
= [2T – (T
max
– T
min
)] / (T
max
– T
min
) (1.12)
in which E
s
(
χ

) is a Chebyshev polynomial in
χ
of degree s (the advantage of this is that the E
s
functions
are orthogonal), the Kirchoff-Rankine equation [48-tho],
ln P = A + BT
-1
+ C ln T, (1.13)
(same form as Eq. (1.6)); the Planck-Riedel equation [48-plarie]
ln P = A + BT
-1
+ C ln T + DP
6
, (1.14)
and the Frost-Kalkwarf equation [53-frokal]
ln P = A + BT
–1
+ C ln T + DPT
–2
(1.15)
Another popular type of function is the Cox equation [36-cox]:
ln (PP
0
–1
) = A (1 – T
b
T) (1.16)
where A is a function of temperature often taken to be
ln A = a + bT + cT

2
(1.17)
Wagner and others [73-wag, 73-wag-1, 77-wag, and 86-amb-1] have proposed a series of related
equations. The simplest is
ln (PP
c
–1
) = (A
τ
+ B
τ

1.5
+ C
τ

3
+ D
τ

6
) / T
r
(1.18)
where
τ
= 1 – T/T
c
, P
c

is the critical pressure and T
c
is the critical temperature. One of the variations [76-
wagewe] is:
ln (PP
c
–1
) = (A
τ
+ B
τ

1.5
+ C
τ

3
+ D
τ

6
+ E
τ

9
) / T
r
(1.19)
1 Introduction [Ref. p. 12
Landolt-Börnstein

New Series IV/20A
8
Iglesias-Silva et al. [87-iglhol] have proposed an accurate, three parameter equation that can fit data from
the triple point to the critical point:
(1.20)
in which
p = 1 + (P – P
t
)/ (P
c
– P
t
)
t = (T – T
t
)/ (T
c
– T
t
)
a
0
= 1 – P
t
/ (P
c
– P
t
)
a

1
= – (a
0
– 1) exp(a
2
– b
0
/R)
a
2
= b
1
/RT
t
a
3
= (T
c
– T
t
)/ T
t
θ
= 0.2
Ν
= 87T
t
/ T
c
a

5
, a
6
, and a
7
are polynomial functions of a
4
An important characteristic of a function is its number of adjustable parameters. When fitting a function to
a set of observed data, the number of data values minus the number of fitting parameters is the degrees of
freedom (f). One measure of how well a function fits data is the standard deviation,
S = (Σ (P
obs
- P
calc
)
2
)
0.5
f
–1
(1.21)
Functions with more parameters are more flexible than those with fewer and can fit experimental data
better over a wider temperature range. If the degree of freedom is zero, any function can fit the data
exactly, however, this is undesirable. Experimentally based data contain experimental errors. A major
objective in fitting data to a function is to obtain a smooth representation of the data that reduces the effect
of random errors and provides a means to interpolate and extrapolate the function. Parameters calculated
with too few degrees of freedom not only fail to reduce random errors, but they may give unreliable
interpolations. It is not wise to make calculations for which the degrees of freedom are less than half the
number of data. For vapor pressure, more degrees of freedom are better. Even when the degrees of
freedom are acceptable, fitting functions with a large number of parameters to data with large errors may

give less reliable results than using a function with fewer parameters.
Vapor pressure equations have been tested and compared [64-mil, 78-amb, 79-scoosb, 80-ambdav,
83-mcg, 85-amb, 90-yalmis, 96-ruzmaj]. Comparing functions with the same number of adjustable
parameters does not always give a clear indication of which is best. Some functions work better for certain
ranges of temperature or pressure, or for certain compounds or classes of compounds. None of the
equations listed above is clearly preferable in all situations. Variations of the Wagner equation are
effective near the critical temperature, but they have no advantage at lower temperatures.
All of the above equations relate the logarithm of pressure to a function of temperature. Thus, the
adjustable parameters are non-linear functions of pressure. Using the least squares criterion with pressure
as a direct function of temperature requires a non-linear fit. It is more common, however, to take ln(P) as a
function of temperature and to select a form from among the Eqs. (1.7,1.9,1.10,1.11,1.12,1.17,1.18).
[]
[]
N
N
N
Rb
tatatata
taRbataaa
p
/1
4
7
3
6
2
54
302
/
310

)1()1()1()1(2
))1/()/exp(()1(
0










−+−+−+−−+
++−++
=
Θ−
Ref. p. 12] 1 Introduction
Landolt-Börnstein
New Series IV/20A
9
Non-linear least squares calculations are more complex than linear calculations. They start with an initial
estimate and find the minimum variance by using a sequence of iterations. It is possible, and common, to
converge upon local minima rather than the global minimum. Numerical least squares techniques are
described in [88-prefla].
The Antoine Eq. (1.8) may be rearranged as:
T log P = AC – B + AT – C log P (1.22)
Thus, if T log(P) is a function of log(P) and T, it is linear in the parameters (AC–B), A, and –C and easily
yield A, B and C. This is the usual procedure for calculating Antoine parameters.
If the truncated virial equation of state (V = RT/P + B’) provides the gas volume, the enthalpy of

vaporization can be calculated from the B and C parameters of Eq. (1.8):
∆
v
H = 2.30258 R(T(T + C)
–1
)
2
(1 + B’P T
–1
) (1.23)
1 Introduction [Ref. p. 12
Landolt-Börnstein
New Series IV/20A
10
1.4 Description of the Tables
The Antoine Eq. (1.8) has been used to represent vapor pressures of pure compounds more than any of the
others because it has several important advantages:
• It is a simple equation, with 3 adjustable parameters that easily can calculate vapor pressure
• It can be solved for temperature, as well as pressure, in closed form
T = B(A – log P)
–1
– C (1.22)
• Linear least squares may be used to obtain the parameters using Eq. (1.20)
• It fits most experimental vapor pressures in the range of 1.5 to 150 kPa
• Useful correlations exist among the Antoine parameters (or at least relationships among them) and
molecular structure.
Data of sufficient accuracy to show significant deviation from the Antoine equation in the 1.5 - 150
kPa exist for only a few compounds. To fit accurate data over a wider range requires a more complex
equation. However, as indicated above using an equation with too many parameters may give undesirable
results.

The Antoine equation, using parameters fit to reliable data in the range 1.5 - 150 kPa, under predicts
higher vapor. This difference increases regularly and smoothly up to the critical temperature. To represent
pressures in this range, the Thermodynamics Research Center at Texas A&M University (TRC) uses the
extended Antoine Eq. (1.9). The additional term 0.43429
χ
n
, where n is a fit parameter, approximate real
data very closely. Because
χ
< 1, and E and F have opposite signs the pair of terms E
χ
8
+ F
χ
12
contribute
appreciably only near the critical temperature. Unless accurate vapor pressures are available in this region,
E and F can be set to zero.
Generally the A, B, and C constants are the same in Equs. (1.8) and (1.9) for the same compound. The
major exceptions are the alcohols with low carbon numbers. Because the exponent n is greater than or
equal to 2.0,
Eqs. (1.8) and (1.9) give equal P and dP/dT at the boundary temperature, T
0
, thus, effecting a smooth
transition. The usual procedure is to fit the simple Antoine equation to data in the 1.5 - 150 kPa region,
which contains most of the accurate data. Then, while keeping the same A, B, and C, the parameters n, E,
and F are fit to the data for temperatures above T
0
. Good results are obtained for T
0

corresponding to
vapor pressures in the range of 120 to 150 kPa.
To retain the Antoine equation for data below 1.5 kPa, a separate set of constants can be fit to the low
range. The TRC Thermodynamic Tables [xx-trchc, xx-trcnh] use a least squares procedure that forces
continuity in P and dP/dT for the same phase at the boundary.
The vapor pressure of the two condensed phases existing at a triple point is the same. However, the
slopes of the vapor pressure curves below and above this temperature are different. Calculation of the
parameters A, B, and C that characterize a particular compound requires accurate vapor pressure data over
a sufficient range of temperature (about 20 deg or more). The constant C is especially sensitive to errors in
the data. When suitable data are used, C is always negative. Within a group of related compounds C,
decreases in a smooth manner as the normal boiling point increases. Examples of groups are isomers or
members of a homologous series. By plotting C vs. T
b
for members of a group that have reliable data, it is
possible to estimate a C value for members that do not have reliable data. A positive C obtained from a
least squares fit is an indication that the data contain large errors or cover a narrow temperature range or
both. The corresponding Antoine equation may give a rough reflection of the data, but it should not be
used for extrapolation.
Parameters of the Antoine Eq. (1.8) and the extended Antoine Eq. (1.9) based upon experimental data
appear as tables in sections 2 to 4 of this volume.
Ref. p. 12] 1 Introduction
Landolt-Börnstein
New Series IV/20A
11
In the Tables the following information is given:
One line presents the substance identification (bold faced):
• 1. An identification number for the compound.
• 2. The empirical (Hill system) gross formula of the compound (the compounds are listed in formula
order sorted by the number of carbon atoms (C), hydrogen atoms (H), and other elements in alphabetical
order).

• 3. The compound name and zero or more synonyms.
• 4. The Registry Number assigned by Chemical Abstracts Services, when available. When a CASRN
is not available, numbers starting at 50000-00-0 identify compounds in the SOURCE Database maintained
by the Thermodynamics Research Center.
The lines following the substance identification provide the data
• 1. Column: Identification of the phase transition (cr - crystal, l - liquid, g - gas).
• 2. Column: A, (n) - The value of A parameter in Eq. (1.8) with P expressed in units of kPa. The value
in parentheses, if present, is the value of n in Eq. (1.9).
• 3. Column: B/K (E) - The value of B in Eq. (1.8). The value in parentheses, if present, contains the
value of E in Eq. (1.9).
• 4. Column: C/K (F) - The value of C in Eq. (1.8) with T in kelvins. The value in parentheses, if
present, contains the value of F in Eq. (1.9).
• 5. Column: T-range [K] - The approximate minimum and maximum temperatures covered by the data.
• 6. Column: Range [K], Rating - The range of temperatures recommended for reliable use of the
equation. If this line contains constants for the extended Antoine Eq. (1.9), the lower limit of the range is
T
0
and the upper limit is T
c
. The lower limit for a liquid phase is never less than the triple point. The upper
limit for crystal phases is never greater than the triple point. The "rating" consists of letters A through D.
The ratings indicate a rough order of reliability for the data used to develop the parameters: A - 0.1%; B -
1%; C - 5%; D - 10%.
• 7. Column: T
b
[K]/P
b
[kPa] - The boiling point at the indicated pressure as calculated from the
Antoine equation with the listed parameters.
• 8. Column: Ref. - An identification of the source of the Antoine constants listed for the designated

compound and phases. Complete references appear in the section ‘References’.
• 8. Column: Note - The numbers refer to the text included in the section ‘Notes’.
The data represented in the Tables has been obtained from several sources:
• TRC Thermodynamic Tables - Hydrocarbons. Identified by [xx-trchc] in the Ref. column. ‘xx’ is the
last two years of the date of issue of the data sheet.
• TRC Thermodynamic Tables - Nonhydrocarbons. Identified by [xx-trcnh] in the Ref. column. ‘xx’ is
the last two years of the date of issue of the data sheet. The original sources of data used for these Tables
appear in the Specific Reference sheets of the TRC Thermodynamic Tables.
• Compilations prepared by the Slovakian Academy of Sciences [79-dykrep, 84-dykrep].
• Other sources - References to original sources of data are given. These refer to sources not used in the
[xx-trchc, xx-recnh, 79-dykrep, 84-dykrep].
The number of significant digits given for the parameters values is also a rough indication of the data
quality for values from [xx-trchc, xx-trcnh] but not for data from other sources.
1 Introduction
Landolt-Börnstein
New Series IV/20A
12
1.5 References for 1
xx-trchc TRC Thermodynamic Tables - Hydrocarbons, Thermodynamics Research Center,
Texas A&M University System, College Station, TX, (19xx).
xx-trcnh TRC Thermodynamic Tables - Non-Hydrocarbons, Thermodynamics Research Center,
Texas A&M University System, College Station, TX, (19xx)
1888-ant Antoine, C.: C. R. Acad Sci. (Paris)
107
(1888) 681.
10-smimez Smith, A., Menzies, A.W.C.: Ann. Phys.
33
(1910) 971.
10-smimez Smith, A., Menzies, A.W.C.: J. Am. Chem. Soc.
32

(1910) 1412.
10-smimez Smith, A., Menzies, A.W.C.: J. Am. Chem. Soc.
32
(1910) 1448.
26-ano International Critical Tables of Numerical Data: Physics. Chemistry. Technology. Vol. 1
(and following volumes). Washburn, E.W.(ed.), New York: McGraw-Hill, 1926.
46-tho Thompson, G.W.: Chem. Rev.
38
(1946) 1.
48-plarie Plank, R., Riedel, L.: Ing. Arch.
16
(1948) 255.
51-par Partington, J.R.: An Advanced Treatise on Physical Chemistry, Vol. 2, Properties of
Liquids, London: Longmans, Gree and Co., 1951.
53-fro/kal Frost, A.A., Kalkwarf, D.R.: J. Chem. Phys.
21
(1953) 264.
64-mil Miller, D.G.: Ind. Eng. Chem.
56
(1964) 46.
70-amb/cou Ambrose, D., Counsel, J.F., Davenport, A.J.: J. Chem. Thermodyn.
2
(1970) 283.
73 wag Wagner, W.: Cryogenics
13
(1973) 470.
73-wag-1 Wagner, W.: Bull. Inst. Int. Froid Annexe.
4
(1973) 65.
76-wagewe Wagner, W., Ewers, J., Pentermann, W.: J. Chem. Thermodyn.

8
(1976) 1049.
77-wag Wagner, W.: A New Correlation Method for Thermodynamic Data Applied to the
Vapor Pressure Curve of Argon, Nitrogen, and Water, IUPAC Thermodynamic Tables
Project Centre, London: Impirial College, 1977.
78-amb Ambrose, D.: J. Chem. Thermodyn.
10
(1978) 765.
79-dykrep Dykyi, J., Repas, M.: Saturated Vapor Pressure of Organic Compounds, Bratislava,
Czech.: Slovakian Academy of Science, 1979.
79-scoosb Scott, D.W., Osborn, A.G.: J. Phys. Chem.
83
(1979) 2714.
80-ambdav Ambrose, D., Davies, R.H.: J. Chem. Thermodyn.
12
(1980) 871.
82-guahon Guang, L., Hongtu, T.: Temperature. Its Measurement and Control in Science and
Industry, Vol. 5, 1982 (see also earlier volumes).
82-mosvan Mosselman, C., van Vugt, W.H., Vos, H.: J. Chem. Eng. Data
27
(1982) 248.
83-mcg McGary, J.: Ind. Eng. Chem. Process Des. Dev.
22
(1983) 313.
84-dykrep Dykyi, J., Repas, M., Svoboda, J.: Saturated Vapor Pressure of Organic Compounds,
Bratislava, Czech.: Slovakian Academy of Science, 1984.
86-amb Ambrose, D.: The Evaluation of Vapour-Pressure Data, London: Dept. of Chemistry,
University College, 1986.
86-amb-1 Ambrose, D.: J. Chem. Thermodyn.
18

(1986) 45.
88-prefla Press, W.H., Flannery, B.P., Teukolsky, S.A., Vetterling, W.T.: Numerical Recipes
in C, Cambridge, UK: Cambridge University Press, 1988.
90-its International Temperature Scale: Metrologia
27
(1990) 3; 107.
90-yalmis Yalkowsky, S.H., Mishra, D.S., Morris, K.H.: Chemosphere
21
(1990) 107.
1 Introduction
Landolt-Börnstein
New Series IV/20A
13
93-fre Frenkel, M.(ed.): Thermochemistry and Equilibria of Organic Compounds, New York:
VCH Publishers, 1993.
95-ambtso Ambrose, D., Tsonopoulos, C.: J. Chem. Eng. Data 40 (1995) 531.
95-ambyou Ambrose, D., Young, C.: J. Chem. Eng. Data 40 (1995) 345.
95-gudtej Gude, M., Teja, A.S.: J. Chem. Eng. Data 40 (1995) 1025.
95-tsoamb Tsonopoulous, C., Ambrose, D.: J. Chem. Eng. Data 40 (1995) 547.
96-dau Daubert, T.E.: J. Chem. Eng. Data 41 (1996) 365.
96-ruzmaj Ruzicka, K., Majer, V.: AIChE J. 42 (1996) 1723.
2.1 Hydrocarbons, C
1
to C
7
[Ref. p. 261
Landolt-Börnstein
New Series IV/20A
14
2 Tabulated Data on Vapor Pressure of Hydrocarbons

2.1 Hydrocarbons, C
1
to C
7
Phase Antoine constants
T
-range Range [K],
T
b
[K]/
P
b
[kPa] Ref.
A
, (
n
)
B
[K], (
E
)
C
[K], (
F
) [K] Rating Note
1CH
4
Methane 74-82-8
cr-g 6.31972 451.64 –4.66 58/89 48/90.69 B 111.63/101.325 74-trchc
l-g 5.7687 395.744 –6.469 92/118 90.69/115 A 74-trchc

l-g 5.7687 395.744 –6.469 118/190 115/190.55 A 74-trchc
(2.51347) (–6.0941) (369.43)
2C
2
H
2
Ethyne 74-86-2
cr-g 8.08413 1148.97 –0.31 148/190 138/192.35 B 189.15/101.325 88-trchc
l-g 5.67374 528.67 –44.36 191/201 192.35/211 B 88-trchc
3C
2
H
4
Ethene 74-85-1
l-g 5.82898 581.901 –17.787 103/122 93/122 B 169.41/101.325 86-trchc
l-g 5.91382 596.526 –16.78 122/188 122/174 A 86-trchc
l-g 5.91382 596.53 –16.78 188/282 174/282.3 A 86-trchc
(2.79132) (9.717) (52.77)
4C
2
H
6
Ethane 74-84-0
cr-g 8.6388 1009.6 –3.15 81/89 71/90.35 B 184.55/101.325 74-trchc
l-g 6.0567 687.3 –14.46 90/133 90.35/133 A 74-trchc
l-g 5.95405 663.72 –16.469 133/198 133/190 A 74-trchc
l-g 5.95405 663.72 –16.469 198/305 190/305.4 A 74-trchc
(2.79768) (–55.054) (2992.1)
5C
3

H
4
Propadiene 463-49-0
cr-g 8.7534 1434.94 0 115/134 106/136.85 C 238.65/101.325 95-trcnh
l-g 6.3495 971.15 –16.5 145/257 136.85/174 C 95-trcnh
l-g 5.6752 734.57 –38.41 178/257 174/253 B 95-trcnh
l-g 5.6752 734.57 –38.41 260/393 253/393 B 95-trcnh
(1.136) (–265) (16325)
6C
3
H
4
Propyne 74-99-7
l-g 6.24555 935.09 –29.57 187/266 175/276 B 249.93/101.325 88-trchc
7C
3
H
6
Cyclopropane 75-19-4
l-g 6.03084 866.15 –25.15 258/398 247/398.2 B 240.35/101.325 75-trchc
(2.6672) (–2.1533) (567.17)
Ref. p. 261] 2.1 Hydrocarbons, C
1
to C
7
Landolt-Börnstein
New Series IV/20A
15
Phase Antoine constants
T-range Range [K], T

b
[K]/P
b
[kPa] Ref.
A
, (
n
)
B
[K], (
E
)
C
[K], (
F
) [K] Rating Note
8C
3
H
6
Propene 115-07-1
l-g 6.48447 934.227 –14 100/163 89/163 B 225.46/101.325 86-trchc
l-g 5.95606 789.624 –25.57 163/238 163/240 A 86-trchc
l-g 5.95606 789.62 –25.57 238/363 240/365 B 86-trchc
(2.67417) (22.1292) (–199.34)
9C
3
H
8
Propane 74-98-6

l-g 6.6956 1030.7 –7.79 101/165 85.5/167 B 231.07/101.325 74-trchc
l-g 5.92828 803.997 –26.11 270/248 167/237 A 74-trchc
l-g 5.92828 803.997 –26.108 248/369 237/369.8 A 74-trchc
(2.55753) (50.655) (–1408.9)
10 C
4
H
2
Butadiyne, Diacetylene 460-12-8
cr-g 10.22178 2707.520 59.540 188/240 188/240 D 234.06/10 26-strkol,
33-tan
Note 1
l-g 5.33975 707.254 –71.198 237/283 235/285 C 265.46/50 26-strkol,
33-tan
11 C
4
H
4
1-Buten-3-yne, Vinylacetylene 689-97-4
l-g 6.61572 1205.758 –16.879 193/243 193/239 B 231.59/10 54-geocav,
71-gol,
31-niecal
l-g 5.32200 663.382 –78.500 233/299 237/300 C 278.54/101.325 54-geocav,
71-gol,
31-niecal,
75-vid-1
12 C
4
H
6

1,2-Butadiene 590-19-2
l-g 6.9608 1282.57 –8.6 140/200 137/205 C 284/101.325 95-trchc
l-g 6.315 1131.55 –21.2 209/290 205/306 B 95-trchc
13 C
4
H
6
1,3-Butadiene 106-99-0
l-g 5.9664 927.21 –34.52 206/212 188/275 B 268.74/101.325 95-trchc
l-g 5.9664 927.21 –34.52 280/425 275/425 B 95-trchc
(2.5164) (23.65) (1970.8)
14 C
4
H
6
1-Butyne 107-00-6
l-g 6.16676 1014.45 –37.41 210/300 200/310 B 281.24/101.325 88-trchc
15 C
4
H
6
2-Butyne 503-17-3
cr-g 6.16281 896.91 –74.09 227/240 217/240.9 B 300.14/101.325 88-trchc
l-g 6.18046 1093.44 –38.19 245/320 240.9/330 B 88-trchc
16 C
4
H
6
Cyclobutene 822-35-5
l-g 6.51606 1207.012 –7.966 197/276 200/276 B 275.58/101.325 41-hei

17 C
4
H
8
1-Butene 106-98-9
l-g 6.7447 1175.63 –13.52 120/194 110/194 B 266.92/101.325 86-trchc
l-g 5.9178 908.8 –34.615 194/288 194/278 A 86-trchc
l-g 5.9178 908.8 –34.61 288/425 278/419.9 B 86-trchc
(2.1058) (–66.743) (5100.7)
2.1 Hydrocarbons, C
1
to C
7
[Ref. p. 261
Landolt-Börnstein
New Series IV/20A
16
Phase Antoine constants
T-range Range [K], T
b
[K]/P
b
[kPa] Ref.
A
, (
n
)
B
[K], (
E

)
C
[K], (
F
) [K] Rating Note
18 C
4
H
8
(E)-2-Butene 624-64-6
l-g 6.27279 1062.92 –23.86 168/201 167.6/201 B 274.03/101.325 86-trchc
l-g 6.00827 967.5 –32.31 201/288 201/282 A 86-trchc
l-g 6.00827 967.5 –32.31 288/428 282/428.6 B 86-trchc
(2.7167) (49.7721) (–1061.2)
19 C
4
H
8
(Z)-2-Butene 590-18-1
l-g 6.38127 1086.09 –26.17 136/203 134.3/203 B 276.87/101.325 86-trchc
l-g 6.00958 967.32 –35.277 205/298 203/292 A 86-trchc
l-g 6.00958 967.32 –35.28 298/438 292/435.5 B 86-trchc
(2.603) (47.1477) (–1082.1)
20 C
4
H
8
Cyclobutane 287-23-0
l-g 6.04436 1025.5 –31.72 210/308 200/295 B 285.66/101.325 75-trchc
l-g 6.04436 1025.5 –31.72 308/460 295/460 B 75-trchc

(2.174) (0) (0)
21 C
4
H
8
Methylcyclopropane 594-11-6
l-g 5.96539 952.41 -37.16 177/278 167/288 C 273.88/101.325 79-dykrep
22 C
4
H
8
2-Methylpropene 115-11-7
l-g 6.41259 1078.57 –19.41 133/194 123/194 B 266.24/101.325 86-trchc
l-g 5.80956 866.25 –38.51 194/288 194/280 A 86-trchc
l-g 5.80956 866.25 -38.51 288/425 280/417.9 B 86-trchc
(1.599) (–150.95) (9633)
23 C
4
H
10
Butane 106-97-8
l-g 6.0127 961.7 –32.14 138/196 134.8/196 B 272.64/101.325 74-trchc
l-g 5.93266 935.773 –34.361 196/298 196/288 A 74-trchc
l-g 5.93266 935.773 –34.361 298/425 288/425.1 B 74-trchc
(2.14767) (–175.62) (12204)
24 C
4
H
10
2-Methylpropane 75-28-5

l-g 5.32368 739.94 –43.15 120/188 110/188 B 261.36/101.325 74-trchc
l-g 6.00272 947.54 –24.28 188/278 188/268 A 74-trchc
l-g 6.00272 947.54 –24.28 278/408 268/407.1 A 74-trchc
(2.6705) (–19.64) (2792)
25 C
5
H
6
Cyclopentadiene 542-92-7
l-g 3.55810 183.257 –195.613 276/314 275/315 C 313.66/101.325 65-hulrei,
67-lesogo
26 C
5
H
6
Ethynylcyclopropane 6746-94-7
l-g 7.0100 1627 0.000 291/320 291/320 B 325.12/101.325 77-lebgut
Note 2
27 C
5
H
8
Bicyclo[2.1.0]pentane 185-94-4
l-g 5.97871 1090.641 –44.597 296/315 295/318 A 312.20/80 74-vardru-3
28 C
5
H
8
Cyclopentene 142-29-0
l-g 6.04518 1121.202 –39.810 195/319 195/280 C,

280/320 A
317.37/101.325 50-forcam,
35-hei,
41-lis
29 C
5
H
8
3-Methyl-1-butyne 598-23-2
l-g 5.981 1025.6 –44.15 225/323 215/333 B 299.5/101.325 88-trchc
Ref. p. 261] 2.1 Hydrocarbons, C
1
to C
7
Landolt-Börnstein
New Series IV/20A
17
Phase Antoine constants
T-range Range [K], T
b
[K]/P
b
[kPa] Ref.
A
, (
n
)
B
[K], (
E

)
C
[K], (
F
) [K] Rating Note
30 C
5
H
8
2-Methyl-1, 3-butadiene 78-79-5
l-g 6.2276 1160.8 –31.4 160/250 140/225 B 307.22/101.325 95-trchc
l-g 6.0266 1079.91 –38.63 253/318 225/338 B 95-trchc
31 C
5
H
8
3-Methyl-1, 2-butadiene 598-25-4
l-g 6.6507 1342.03 –22.2 180/251 160/225 B 314/101.325 95-trchc
l-g 6.1009 1120.26 –40.42 250/328 235/350 A 95-trchc
32 C
5
H
8
1-Methylcyclobutene 1489-60-7
l-g 6.3291 1362.2 0 290/316 286/322 C 79-dykrep
33 C
5
H
8
Methylenecyclobutane 1120-56-5

l-g 6.03165 1100.497 –41.999 274/348 270/350 A 315.35/101.325 75-lebleb,
80-osbsco
34 C
5
H
8
1,2-Pentadiene 591-95-7
l-g 6.0536 1122.72 –41.5 160/230 145/235 B 318.01/101.325 95-trchc
l-g 6.04914 1107.9 –43.99 249/335 235/350 A 95-trchc
35 C
5
H
8
(E)-1,3-Pentadiene 2004-70-8
l-g 6.3972 1251.59 –28.4 200/255 185/235 B 315.18/101.325 95-trchc
l-g 6.0544 1112.26 –40.44 250/330 235/350 B 95-trchc
36 C
5
H
8
(Z)-1,3-Pentadiene 1574-41-0
l-g 6.1976 1176.14 –36.4 236/252 224/235 A 317.22/101.325 95-trchc
l-g 6.0595 1114.03 –42.39 252/325 235/350 A 95-trchc
37 C
5
H
8
1,4-Pentadiene 591-93-5
l-g 5.9643 1030.27 –39.5 150/237 140/220 B 299.12/101.325 95-trchc
l-g 5.9904 1032.25 –40.05 235/310 220/330 A 95-trchc

38 C
5
H
8
2,3-Pentadiene 591-96-8
l-g 6.454 1281.57 –31.7 160/257 150/257 B 321.41/101.325 95-trchc
l-g 6.1084 1137.67 –44.09 257/335 257/356 A 95-trchc
39 C
5
H
8
1-Pentyne 627-19-0
l-g 6.0026 1068.1 –46.15 233/334 223/344 B 313.33/101.325 88-trchc
40 C
5
H
8
2-Pentyne 627-21-4
l-g 5.9742 1111.6 –49.15 245/352 235/362 B 329.22/101.325 88-trchc
41 C
5
H
8
Spiro[2.2]pentane 157-40-4
l-g 6.03785 1087.511 –42.395 276/344 275/350 A 312.11/101.325 50-scofin-1
42 C
5
H
8
Vinylcyclopropane 693-86-7

l-g 6.8141 1509 0.000 290/310 290/310 B 313.83/101.325 77-lebgut
43 C
5
H
10
Cyclopentane 287-92-3
l-g 9.7573 3319.68 112.45 124/236 114/236 B 322.41/101.325 91-trchc
l-g 6.06783 1152.57 –38.64 236/348 236/335 A 91-trchc
l-g 6.06783 1152.57 –38.64 348/512 335/511.8 B 91-trchc
(3.36721) (284.39) (–1665)
44 C
5
H
10
1,1-Dimethylcyclopropane 1630-94-0
l-g 5.87625 1001.62 –35 293.78/293.78 273/303 C 293.78/101.325 87-trcsp
45 C
5
H
10
cis-1,2-Dimethylcyclopropane 930-18-7
l-g 5.87145 1063.77 –35 310.18/310.18 290/320 C 310.18/101.325 87-trcsp
2.1 Hydrocarbons, C
1
to C
7
[Ref. p. 261
Landolt-Börnstein
New Series IV/20A
18

Phase Antoine constants
T-range Range [K], T
b
[K]/P
b
[kPa] Ref.
A
, (
n
)
B
[K], (
E
)
C
[K], (
F
) [K] Rating Note
46 C
5
H
10
trans-1,2-Dimethylcyclopropane 2402-06-4
l-g 5.85706 1025.84 –35 301.36/301.36 281/311 C 301.36/101.325 87-trcsp
47 C
5
H
10
Ethylcyclopropane 1191-96-4
l-g 5.94387 1079.37 –35 309.08/309.08 289/319 C 309.08/101.325 87-trcsp

48 C
5
H
10
2-Methyl-1-butene 563-46-2
l-g 6.53281 1254.5 –23.89 140/223 135.6/223 B 304.3/101.325 86-trchc
l-g 5.97127 1039.69 –42.12 223/318 223/315 B 86-trchc
l-g 5.97127 1039.69 –42.12 318/471 315/470.1 B 86-trchc
(2.53166) (63.6071) (–1283.3)
49 C
5
H
10
2-Methyl-2-butene 513-35-9
l-g 6.57599 1297.31 –24.22 143/229 139.4/229 C 311.7/101.325 86-trchc
l-g 6.09149 1124.33 –36.52 229/328 229/325 B 86-trchc
l-g 6.09149 1124.23 –36.52 328/481 325/481.1 B 86-trchc
(3.2398) (136.358) (–5322.9)
50 C
5
H
10
3-Methyl-1-butene 563-45-1
l-g 6.6662 1253.84 –18.39 133/213 120/213 B 293.21/101.325 86-trchc
l-g 5.94945 1012.37 –36.503 213/308 213/304 A 86-trchc
l-g 5.94945 1012.37 –36.5 308/455 304/453.1 B 86-trchc
(2.7222) (95.8745) (–3435.8)
51 C
5
H

10
Methylcyclobutane 598-61-8
l-g 5.88487 1060.75 –36 309.45/309.45 289/319 C 309.45/101.325 87-trcsp
52 C
5
H
10
1-Pentene 109-67-1
l-g 6.76566 1323.6 –18.74 138/222 128/222 B 303.11/101.325 86-trchc
l-g 5.96914 1044.01 –39.7 222/318 222/312 B 86-trchc
l-g 5.96914 1044.01 –39.7 318/465 312/464.7 B 86-trchc
(2.5751) (122.883) (–4873.4)
53 C
5
H
10
(E)-2-Pentene 646-04-8
l-g 6.59318 1290.5 –24.1 142/228 132.9/228 B 309.49/101.325 86-trchc
l-g 6.02473 1080.76 –40.583 228/328 228/321 A 86-trchc
l-g 6.02473 1080.76 –40.58 328/475 321/474.1 B 86-trchc
(2.64887) (90.3273) (–3327.6)
54 C
5
H
10
(Z)-2-Pentene 627-20-3
l-g 6.68458 1318.85 –23.16 143/228 133/228 B 310.07/101.325 86-trchc
l-g 5.96798 1052.44 –44.457 228/328 228/322 A 86-trchc
l-g 5.96798 1052.44 –44.46 328/481 322/475.1 B 86-trchc
(2.443) (66.8925) (–1317.8)

55 C
5
H
12
2,2-Dimethylpropane 463-82-1
cr-g 6.3305 1020.7 –43.15 221/253 211/256.6 C 282.65/101.325 74-trchc
l-g 5.83916 938.234 –37.901 259/298 256.6/295 A 74-trchc
l-g 5.83916 938.234 –37.901 298/434 295/433.7 B 74-trchc
(2.42328) (34.505) (580.56)
56 C
5
H
12
2-Methylbutane 78-78-4
l-g 5.93925 1031.949 –38.646 255/323 212/309 A 300.99/101.325 91-ewigoo/
trchc
l-g 5.92023 1022.88 –39.69 318/460 309/460.4 B 74-ewigoo/
trchc
(2.14912) (–227.07) (19674)
Ref. p. 261] 2.1 Hydrocarbons, C
1
to C
7
Landolt-Börnstein
New Series IV/20A
19
Phase Antoine constants
T-range Range [K], T
b
[K]/P

b
[kPa] Ref.
A
, (
n
)
B
[K], (
E
)
C
[K], (
F
) [K] Rating Note
57 C
5
H
12
Pentane 109-66-0
cr-g 10.7094 2005 -8.15 142/142 132/143.4 B 309.21/101.325 74-trchc
l-g 6.6895 1339.4 –19.03 143/219 143.4/219 B 74-trchc
l-g 5.97786 1064.84 –41.138 219/328 219/318 A 74-trchc
l-g 5.97786 1064.84 –41.138 328/470 318/469.7 A 74-trchc
(2.45751) (78.607) (–1782.3)
58 C
6
H
2
1,3,5-Hexatriyne 3161-99-7
l-g 6.65097 1641.600 0.000 253/263 253/263 D 258.52/2 50-hun

Note 9
59 C
6
H
6
Benzene 71-43-2
cr-g 8.72391 2107.85 –16.45 210/276 218/278.68 B 353.24/101.325 96-trchc
l-g 5.98523 1184.236 –55.623 280/374 278.68/376 A 95-trchc
l-g 5.98523 1184.24 –55.623 378/562 376/562.12 A 95-trchc
(2.3835) (12.283) (664.01)
60 C
6
H
6
1,3-Hexadien-5-yne 10420-90-3
l-g 5.72775 1083.262 –67.033 233/283 220/290 C 256.16/1 54-geocav
61 C
6
H
6
1,5-Hexadien-3-yne 821-08-9
l-g 3.06765 327.888 –148.526 223/283 220/290 C 255.41/1 54-geocav,
31-niecal
62 C
6
H
6
2,4-Hexadiyne 2809-69-0
cr-g 9.47269 2709.223 –17.619 273/338 273/283 D,
283/338 C

337.38/10 86-meymey
l-g 6.24134 1457.409 –58.576 338/408 338/383 B,
383/410 A
402.66/101.325 86-meymey
63 C
6
H
8
1,3-Cyclohexadiene 592-57-4
l-g 5.98705 1203.812 –51.104 307/363 305/370 A 353.47/101.325 74-letmar,
73-meyhot
64 C
6
H
8
1,4-Cyclohexadiene 628-41-1
l-g 6.33811 1429.778 –32.568 304/323 300/330 B 316.42/20 74-letmar
65 C
6
H
8
cis-1,3,5-Hexatriene 2612-46-6
l-g 6.39492 1427.666 –29.569 306/323 300/335 A 309.84/20 74-letmar
66 C
6
H
8
cis, anti, cis-Tricyclo[3.1.0.0(2,4)]hexane 21531-33-9
l-g 6.00091 1222.733 –38.019 273/330 272/333 B 322.25/50 79-letorc
67 C

6
H
10
cis-Bicyclo[3.1.0]hexane 285-58-5
l-g 6.81076 1649.786 –9.091 298/320 295/320 B,
320/355 C
308.52/20 70-chamcn,
59-simsmi
Note 4
68 C
6
H
10
Cyclohexene 110-83-8
l-g 6.07024 1260.609 –45.847 228/325 226/329 B 310.17/20 50-forcam,
41-lis
l-g 6.00794 1227.982 –49.265 316/365 324/365 A 356.09/101.325 50-forcam,
73-meyhot
69 C
6
H
10
1,1-Dimethylbutadiene 926-56-7
l-g 5.79239 1114.99 –55 349.45/349.45 329/359 C 349.45/101.325 87-trcsp
2.1 Hydrocarbons, C
1
to C
7
[Ref. p. 261
Landolt-Börnstein

New Series IV/20A
20
Phase Antoine constants
T-range Range [K], T
b
[K]/P
b
[kPa] Ref.
A
, (
n
)
B
[K], (
E
)
C
[K], (
F
) [K] Rating Note
70 C
6
H
10
2,3-Dimethyl-1,3-butadiene 513-81-5
l-g 6.27858 1318.526 –33.077 273/342 270/345 B 341.66/101.325 55-cummcl
71 C
6
H
10

3,3-Dimethyl-1-butyne 917-92-0
l-g 5.9407 1045.6 –45.15 230/332 222/340 C 310.87/101.325 88-trchc
72 C
6
H
10
1,3-Dimethylcyclobutene 7411-24-7
l-g 6.9809 1633 0.000 268/295 265/329 C 273.04/10 65-fremar
Note 2
73 C
6
H
10
2-Ethyl-1,3-butadiene 3404-63-5
l-g 7.47668 1603.81 –55 348.15/348.15 328/358 C 348.15/101.325 87-trcsp
74 C
6
H
10
1,2-Hexadiene 592-44-9
l-g 5.728 1094.91 –55 349.15/349.15 329/359 C 349.15/101.325 87-trcsp
75 C
6
H
10
trans-1,3-Hexadiene 20237-34-7
l-g 5.70471 1015.624 –70.813 299/320 295/320 B 301.44/20 74-letmar
76 C
6
H

10
(Z)-1,3-Hexadiene 14596-92-0
l-g 5.80201 1105.29 -55 346.15/346.15 326/356 C 346.15/101.325 87-trcsp
77 C
6
H
10
trans-1,4-Hexadiene 7319-00-8
l-g 6.07919 1207.525 –41.873 304/203 300/330 B 311.58/40 74-letmar
78 C
6
H
10
(Z)-1,4-Hexadiene 7318-67-4
l-g 5.78504 1070.11 –55 338.15/338.15 318/348 C 338.15/101.325 87-trcsp
79 C
6
H
10
1,5-Hexadiene 592-42-7
l-g 5.98314 1159.908 –40.998 286/320 275/335 B 332.62/101.325 55-cummcl,
74-letmar,
54-pomfoo-1
80 C
6
H
10
2,3-Hexadiene 592-49-4
l-g 5.70738 1059.23 –55 341.15/341.15 321/351 C 341.15/101.325 87-trcsp
81 C

6
H
10
trans, trans-2,4-Hexadiene 5194-51-4
l-g 5.96105 1190.545 –54.759 304/323 300/325 A 310.24/20 74-letmar
82 C
6
H
10
(E, Z)-2,4-Hexadiene 5194-50-3
l-g 5.81189 1134.81 –55 353.15/353.15 333/363 C 353.15/101.325 87-trcsp
83 C
6
H
10
(Z, Z)-2,4-Hexadiene 6108-61-8
l-g 5.81189 1134.81 –55 353.15/353.15 333/363 C 353.15/101.325 87-trcsp
84 C
6
H
10
1-Hexyne 693-02-7
l-g 6.0401 1183.6 –51.15 257/368 249/376 C 344.48/101.325 88-trchc
85 C
6
H
10
2-Hexyne 764-35-2
l-g 5.94854 1146.825 –66.716 300/358 285/300 C,
300/360 B

357.58/101.325 41-cameby-1,
86-eiselv,
81-elvots
86 C
6
H
10
3-Hexyne 928-49-4
l-g 6.0144 1208.3 –53.15 264/378 254/388 B 354.58/101.325 88-trchc
87 C
6
H
10
Isopropylallene 13643-05-5
l-g 5.68937 1061.44 –55 343.15/343.15 323/353 C 343.15/101.325 87-trcsp