Ideally this is a vegetable glycerine mixed with grain alcohol, both of which are natural. Actually, though, it is usually a synthetic petrochem mix used as a humectant that has been known to cause allergic and toxic reactions. Avoid.
Propylene glycol (IUPAC name: propane-1,2-diol) is a viscous, colorless liquid, which is nearly odorless but possesses a faintly sweet taste. Its chemical formula is CH3CH(OH)CH2OH. Containing two alcohol groups, it is classed as a diol. It is miscible with a broad range of solvents, including water, acetone, and chloroform. In general, glycols are non-irritating and have very low volatility.
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| Names | |||
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| Preferred IUPAC name
Propane-1,2-diol | |||
| Other names
Propylene glycol
α-Propylene glycol 1,2-Propanediol 1,2-Dihydroxypropane Methyl ethyl glycol Methylethylene glycol | |||
| Identifiers | |||
3D model (JSmol)
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| ChEBI | |||
| ChEMBL | |||
| ChemSpider | |||
| ECHA InfoCard | 100.000.307 | ||
| EC Number |
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| E number | E1520 (additional chemicals) | ||
| KEGG | |||
PubChem CID
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| RTECS number |
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| UNII |
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CompTox Dashboard (EPA)
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| Properties | |||
| C3H8O2 | |||
| Molar mass | 76.095 g·mol−1 | ||
| Appearance | colourless liquid | ||
| Odor | odorless | ||
| Density | 1.036 g/cm3 | ||
| Melting point | −59 °C (−74 °F; 214 K) | ||
| Boiling point | 188.2 °C (370.8 °F; 461.3 K) | ||
| Miscible | |||
| Solubility in ethanol | Miscible | ||
| Solubility in diethyl ether | Miscible | ||
| Solubility in acetone | Miscible | ||
| Solubility in chloroform | Miscible | ||
| log P | -1.34 | ||
| Thermal conductivity | 0.34 W/m-K (50% H2O @ 90 °C (194 °F)) | ||
| Viscosity | 0.042 Pa·s | ||
| Pharmacology | |||
| QA16QA01 (WHO) | |||
| Hazards | |||
| GHS labelling: | |||
Preview warning: H-phrases: "" not found
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Preview warning: P-phrases: "" not found
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| NFPA 704 (fire diamond) | |||
Related glycols
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Ethylene glycol, 1,3-propanediol | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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It is produced on a large scale primarily for the production of polymers. In the European Union, it has E-number E1520 for food applications. For cosmetics and pharmacology, the number is E490. Propylene glycol is also present in propylene glycol alginate, which is known as E405. Propylene glycol is a compound which is GRAS (generally recognized as safe) by the US Food and Drug Administration under 21 CFR x184.1666, and is also approved by the FDA for certain uses as an indirect food additive. Propylene glycol is approved and used as a vehicle for topical, oral, and some intravenous pharmaceutical preparations in the U.S. and in Europe.
