7855. Propylene Glycol

Nomenclature

CAS number: 57-55-6
1,2-Propanediol; methyl glycol; 1,2-dihydroxypropane.
C3H8O2; mol wt 76.09.
C 47.35%, H 10.60%, O 42.05%.

Description and references

Prepn from glycerol: Raschig, Prahl, Ber. 61, 185 (1928). Prepn of levorotatory propylene glycol from hydroxyacetone by yeast reduction: Levene, Walti, Org. Synth. coll. vol. II, 545 (1943). Prepn of S-(+)-form: E. Baer, H. O. L. Fischer, J. Am. Chem. Soc. 70, 609 (1948); C. Melchiorre, Chem. Ind. (London) 1976, 218. Manuf from propylene oxide by hydration: Faith, Keyes & Clark's Industrial Chemicals, F. A. Lowenheim, M. K. Moran, Eds. (Wiley-Interscience, New York, 4th ed., 1975) pp 688-691. Toxicity data: W. Bartsch et al., Arzneim.-Forsch. 26, 1581 (1976). GC/MS determn in plasma: C. Giachetti et al., Biomed. Environ. Mass Spectrom. 18, 592 (1989). Review of toxicity, metabolism and biochemistry: Ruddick, Toxicol. Appl. Pharmacol. 21, 102 (1972); of toxicology and human exposure: Toxicological Profile for Ethylene Glycol and Propylene Glycol (US DHHS, PB98-101109, 1997) 250 pp.

Chemical structure

Derivative

dl-Form.

Properties

Hygroscopic, viscous liquid. Slightly acrid taste. mp -59°. bp760 188.2°; bp400 168.1°; bp200 149.7°; bp100 132.0°; bp60 119.9°; bp40 111.2°; bp20 96.4°; bp10 83.2°; bp5 70.8°; bp1.0 45.5°. d425 1.036. Flash pt, open cup: 210°F (99°C). nD20 1.4324. Miscible with water, acetone, chloroform. Sol in ether. Will dissolve many essential oils, but is immiscible with fixed oils. It is a good solvent for rosin. Under ordinary conditions propylene glycol is stable, but at high temps it tends to oxidize giving rise to products such as propionaldehyde, lactic acid, pyruvic acid and acetic acid. LD50 orally in rats: 25 ml/kg (Bartsch).

Derivative

l-Form.

Nomenclature

CAS number: 4254-14-2
(R)-1,2-Propanediol.

Properties

bp12 88-90°, bp760 187-189°. [α]D20 -15.0°.

Derivative

d-Form.

Nomenclature

CAS number: 4254-15-3
(S)-1,2-Propanediol.

Properties

bp14 94-96°. bp765 186-188°. d25 1.04. nD23.5 1.4312. [α]D23 +20.1° (c = 7.5 in water). [α]D22 +4.2° (c = 6.6 in dry ethanol). [α]D20 +15.84° (neat).

Use

Nontoxic antifreeze in breweries and dairy establishments. Substitute for ethylene glycol and glycerol. In the manuf of synthetic resins and de-icing solutions. Emulsifier in foods; solvent for food colors and flavors. Pharmaceutic aid (humectant, solvent). As mist to disinfect air; to create artificial smoke and mist for theatrical use.

Therapeutic Category (Veterinary)

Glucogenic (orally) in ruminants.