These tables give selected values of the electric dipole moment μ for over 900 molecules. When available, values determined by microwave spectroscopy, molecular beam electric resonance, and other high-resolution spectroscopic techniques were selected. Otherwise, the values come from measurements of the dielectric constant in the gas phase or, if these do not exist, in the liquid phase.
Entries are listed alphabetically by compound name. This is followed by a line formula for simple structures or, for more complex compounds, the molecular formula in Hill order.
The dipole moment is given in debye units (D). The conversion factor to SI units is 1 D = 3.33564 × 10–30 C m.
When the accuracy of a dipole moment value is explicitly stated, e.g., 1.234(12), where digit(s) in parentheses represent the uncertainty in the last digit(s) of the value, the stated uncertainty generally indicates two standard deviations. When no uncertainty is given, the value may be assumed to be precise to a few units in the last decimal place. However, if more than three decimal places are given, the exact interpretation of the final digits may require analysis of the vibrational averaging. Other information on molecules that have been studied by spectroscopy, such as the components of the dipole moment in the molecular framework and the variation with vibrational state and isotopic species, may be found in the references.
Values measured in the gas phase that are questionable because of undetermined error sources are preceded by ≈. Values obtained by liquid-phase measurements, which sometimes have large errors because of association effects, are followed by liq.
Table 1 gives dipole moments of individual molecules in the gas or liquid phase. Column definitions for Table 1 are as follows.
Column heading | Definition |
Name | Name of compound; compounds are listed alphabetically by name |
Mol. form. | Molecular formula of compound, in Hill order |
μ | Dipole moment, in units D |
Ref. | Reference number |
Table 2 lists dipole moments of individual conformers of molecules that can exist in different structural configurations, related by internal rotation around single bonds. These conformers exist long enough to be measured by gas-phase microwave spectroscopic techniques but interconvert too rapidly to be isolated as bulk samples. The conformers are designated as gauche, trans, axial, etc. Because the notation of conformers is not well standardized, the references should be consulted for full details of the structure. Column definitions for Table 2 are as follows.
Column heading | Definition |
Name | Name of compound; compounds are listed alphabetically by name |
Mol. form. | Molecular formula of compound, in Hill order |
Conformer | Conformer name; see text for discussion |
μ | Dipole moment, in units D |
Ref. | Reference number |
Name | Synonym | Mol. form. | Mol. form. | CAS Reg. No. | μ/D | Ref. |
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Acenaphthene | 1,2-Dihydroacenaphthylene | C12H10 | C12H10 | 83-32-9 | ≈0.85 | 1 |
Acetaldehyde | Ethanal | C2H4O | CH3CHO | 75-07-0 | 2.750(6) | 3 |
Acetamide | Ethanamide | C2H5NO | CH3CONH2 | 60-35-5 | 3.68(3) | 5 |
Acetic acid | Ethanoic acid | C2H4O2 | CH3COOH | 64-19-7 | 1.70(3) | 2 |
Acetic anhydride | Acetyl acetate | C4H6O3 | C4H6O3 | 108-24-7 | ≈2.8 | 1 |
Acetone | 2-Propanone | C3H6O | (CH3)2CO | 67-64-1 | 2.88(3) | 1 |
Acetonitrile | Methyl cyanide | C2H3N | CH3CN | 75-05-8 | 3.92519 | 5 |
Acetophenone | Methyl phenyl ketone | C8H8O | C6H5C=OCH3 | 98-86-2 | 3.02(6) | 1 |
Acetyl chloride | Ethanoyl chloride | C2H3ClO | CH3COCl | 75-36-5 | 2.72(14) | 1 |
Acetylene-carbon dioxide complex | C2H2·CO2 | C2H2·CO2 | 0.161(1) | 22 | ||
Acetylene-carbon monoxide complex | C2H2·CO | C2H2·CO | 0.311(1) | 32 | ||
Acetylene-carbon oxysulfide trimer complex | C2H2·C3O3S3 | C2H2·(OCS)3 | 1.23(2) | 53 | ||
Acetylene-hydrogen cyanide complex | C2H2·CHN | C2H2·HCN | 3.29(3) | 32 | ||
Acetylene-sulfur dioxide complex | C2H2O2S | C2H2·SO2 | 1.683(5) | 93 | ||
Acetyl fluoride | Ethanoyl fluoride | C2H3FO | CH3COF | 557-99-3 | 2.96(3) | 1 |
Acrylonitrile | Propenenitrile | C3H3N | CH2=CHCN | 107-13-1 | 3.92(7) | 5 |
Allenyl isocyanide | Isocyanoallene | C4H3N | CH2=C=CHNC | 41108-74-1 | 3.81(9) | 102 |
Allyl alcohol | 2-Propen-1-ol | C3H6O | C3H6O | 107-18-6 | 1.60(8) | 1 |
Allylamine | 2-Propen-1-amine | C3H7N | CH2=CHCH2NH2 | 107-11-9 | ≈1.2 | 1 |
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