Table 1.
Physical characteristics of selected essential oils constituents.
|
Name IUPAC Name (chemical class) |
Molecular formula Molecular weight |
Organoleptic description |
Flash point | Solubility |
Density (g/cm3) |
Index of refraction |
Optical rotation |
LogP |
Natural occurence |
Stability | References |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Linalool 3,7-dimethylocta-1,6-dien-3-ol (acyclic monoterpene) |
C10H18O 154.25 g/mol |
Colorless to pale yellow liquid with floral, spicy, wood odor | 160°F | Soluble in alcohol, ether, fixed oils, propylene glycol; insoluble in glycerin | 0.870 at 15/4°C |
1.4627 | −2 to +2° | 2.97 | Lamiaceae (Origanum, mint, thyme), Lauraceae (laurels), Rutaceae (citrus fruits) | Forced autoxidation after exposure atmospheric oxygen; stable in complex fragrances stored in half-empty bottles, opened every 14 days; only traces of hydroperoxides detected | Baser and Buchbauer, 2010; PubChem, n.d. |
| α-Pinene 2,6,6-trimethylbicyclo [3.1.1] hept-2-ene (bicyclic monoterpene) |
C10H16 136.23 g/mol |
Clear colorless liquid with a turpentine odor | 91°F | Soluble in alcohol, chloroform, ether, glacial acetic acid, fixed oils | 0.8592 at 20/4°C |
1.4663 at 20°C |
+51.14 at 20°C/D | 4.4 | Very widespread, pine trees; Salvia officinalis |
Autoxidation after exposure to light | Schrader et al., 2001 Baser and Buchbauer, 2010; PubChem, n.d. |
| Limonene 1-methyl-4-prop-1-en-2-ylcyclohexene (monocyclic monoterpene) |
C10H16 136.23 g/mol |
Clear to light yellow liquid with pleasant lemon-like odor | 97°F | Soluble in 5 volumes alcohol; miscible with benzene, chloroform, ether, carbon disulfide, petroleum ether and oils | 0.8402 at 20.85/4°C | 1.4723–1.4737 at 20°C/D |
+94 to +99° at 25°C/D | 4.57 | Rutaceae (citrus fruits), pines, junipers | Autoxidation in elevated temperatures to form isoprene. It oxidizes easily in moist air to produce carveol, carvone, and limonene oxide. | Karlberg et al., 1992; PubChem, n.d. |
| Chamazulene 7-ethyl-1,4-dimethylazulene (degradation product of sesquiterpenoid matricin) |
C14H16 184.28 g/mol |
Blue liquid | 278°F | Soluble in alcohols and fixed oils | 0.9883 at 20°C |
1.584 | Not specified | 3.97 | Chamomile, wormwood and yarrow | Not particularly stable, the deep blue color can change to green and even yellow on aging | Baser and Buchbauer, 2010; Molbase, n.d.; PubChem, n.d. |
| Eugenol 2-methoxy-4-prop-2-enylphenol (Phenylpropanoid) |
C10H12O2 164.2 g/mol |
Clear colorless pale yellow or amber-colored liquid with odor of cloves | 212°F | Soluble in all proportions of alcohol, ether, chloroform, or glacial acetic acid. | 1.0652 at 20°C |
1.5405 at 20°C/D |
−1°20′ to −0°49′ | 2.27 | Cloves | Darkens and thickens on exposure to air | PubChem, n.d. |
| Methyl anthranilate methyl 2-aminobenzoate |
C8H9NO2 151.16 g/mol |
Pale yellow liquid with bluish fluorescence and odor of grapes | 212°F | Slightly soluble in water; freely soluble in alcohol or ether; soluble in fixed oils, propylene glycol, volatile oils; slightly soluble in mineral oil; insoluble in glycerol | 1.168 at 20°C |
1.5810 at 25°C/D |
Not specified | 1.88 | Grapes, bergamot, citrus fruits, jasmie | Undergoes direct photolysis under UVC and UVB irradiation | Lanzafame et al., 2017; PubChem, n.d. |