The permittivity of a substance (often called the dielectric constant) is the ratio of the electric displacement D to the electric field strength E when an external field is applied to the substance. The quantity tabulated here is the relative permittivity, which is the ratio of the actual permittivity to the permittivity of a vacuum; it is a dimensionless number.
The table gives the static relative permittivity ε, i.e., the relative permittivity measured in static fields or at low frequencies where no relaxation effects occur. When available, a temperature close to 20 °C was chosen, or (as it is the case for many of the substances included here) ε is given at the only temperature for which data are available. The static permittivity refers to nominal atmospheric pressure as long as the corresponding temperature is below the normal boiling point. Otherwise, at temperatures above the normal boiling point, the pressure is understood to be the saturated vapor pressure of the substance.
For substances where information on the temperature dependence of the permittivity is available, the table gives the coefficients of a simple polynomial fitting of permittivity to temperature with an equation of the form
ε(T) = a + bT + cT2 + dT3
where T is the absolute temperature in K.
The coefficients of the fitting equation can be used to calculate dielectric constants within the fitted temperature range but should not be used for extrapolation outside the stated temperature range. The user who needs dielectric constant data with more accuracy than can be provided by this equation is referred to Ref. 1, which gives the original data together with their literature source. Column definitions for the table are as follows.
The notation E-xy means 10-xy.
Column heading | Definition |
Name | Name of liquid; substances are listed alphabetically by systematic name |
Mol. form. | Molecular formula of liquid |
ε | Static relative permittivity (dielectric constant); the value is at the temperature in °C specified by the superscript |
a | Constant in the temperature fitting equation |
b | Coefficient of T in the temperature fitting equation |
c | Coefficient of T2 in the temperature fitting equation |
d | Coefficient of T3 in the temperature fitting equation |
Temp. range | Temperature range for which the fitting equation is valid, in K |
Name | Synonym | Mol. form. | CAS Reg. No. | Formula | ε | a | b | c | d | Temp. range/K |
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Acetaldehyde | Ethanal | C2H4O | 75-07-0 | CH3CHO | 21.018 | |||||
Acetaldoxime | Acetaldehyde oxime | C2H5NO | 107-29-9 | C2H5NO | 4.7025 | |||||
Acetamide | Ethanamide | C2H5NO | 60-35-5 | CH3CONH2 | 67.691 | -0.20055E+03 | 0.15515E+01 | -0.22392E-02 | 364 - 448 | |
Acetic acid | Ethanoic acid | C2H4O2 | 64-19-7 | CH3COOH | 6.2020 | -0.15731E+02 | 0.12662E+00 | -0.17738E-03 | 293 - 363 | |
Acetic anhydride | Acetyl acetate | C4H6O3 | 108-24-7 | C4H6O3 | 22.4520 | |||||
2-Acetonaphthone | C12H10O | 93-08-3 | 13.0360 | 0.14538E+03 | -0.73040E+00 | 0.10000E-02 | 333 - 363 | |||
Acetone | 2-Propanone | C3H6O | 67-64-1 | (CH3)2CO | 21.0120 | 0.88157E+02 | -0.34300E+00 | 0.38925E-03 | 273 - 323 | |
Acetonitrile | Methyl cyanide | C2H3N | 75-05-8 | CH3CN | 36.6420 | 0.29724E+03 | -0.15508E+01 | 0.22591E-02 | 288 - 333 | |
Acetophenone | Methyl phenyl ketone | C8H8O | 98-86-2 | C6H5C=OCH3 | 17.4425 | 0.26099E+02 | 0.64048E-02 | -0.11905E-03 | 298 - 333 | |
4-Acetylanisole | C9H10O2 | 100-06-1 | 17.340 | |||||||
Acetyl chloride | Ethanoyl chloride | C2H3ClO | 75-36-5 | CH3COCl | 15.822 | |||||
Acetylene | Ethyne | C2H2 | 74-86-2 | HC≡CH | 2.4841-78 | |||||
N-Acetylethanolamine | C4H9NO2 | 142-26-7 | 96.625 | 0.37016E+03 | -0.13113E+01 | 0.13214E-02 | 298 - 348 | |||
2-(Acetyloxy)benzoic acid | Acetylsalicylic acid | C9H8O4 | 50-78-2 | C9H8O4 | 6.5560 | 0.69994E+01 | -0.14553E-02 | 333 - 416 | ||
4-Acetylthioanisole | C9H10OS | 1778-09-2 | 11.3482 | |||||||
Acrylonitrile | Propenenitrile | C3H3N | 107-13-1 | CH2=CHCN | 33.020 | 0.11109E+03 | -0.36806E+00 | 0.34879E-03 | 233 - 413 | |
Allene | C3H4 | 463-49-0 | CH2=C=CH2 | 2.025-4 | 0.26049E+01 | -0.44147E-03 | -0.63420E-05 | 156 - 269 | ||
Allyl alcohol | 2-Propen-1-ol | C3H6O | 107-18-6 | C3H6O | 19.720 | 0.62714E+02 | -0.14771E+00 | 0.37879E-05 | 213 - 303 | |
Allylbenzene | 2-Propenylbenzene | C9H10 | 300-57-2 | 2.6320 |