Name: Phenylethyl Alcohol
CAS No: 2-Phenylethanol [60-12-8]
USP: Phenylethyl Alcohol
Benzeneethanol; benzyl carbinol; benzylmethanol; b-fenylethanol; b-fenethylalkohol; b-hydroxyethyl benzene; PEA; phenethanol; bphenylethyl alcohol; 2-phenylethyl alcohol; phenylethanol.
2-Phenylethanol [60-12-8]
C8H10O 122.17
Phenylethyl alcohol is used as an antimicrobial preservative in nasal, ophthalmic, and otic formulations at 0.25–0.5% v/v concentration; it is generally used in combination with other preservatives.(1–3) Phenylethyl alcohol has also been used on its own as an antimicrobial preservative at concentrations up to 1% v/v in topical preparations. At this concentration, mycoplasmas are inactivated within 20 minutes, although enveloped viruses are resistant.(4) Phenylethyl alcohol is also used in flavors and as a perfumery component, especially in rose perfumes.
Phenylethyl alcohol is a clear, colorless liquid with an odor of rose oil. It has a burning taste that irritates and then anesthetizes mucous membranes.
See Table I.
Antimicrobial activity Phenylethyl alcohol has moderate antimicrobial activity although it is relatively slow acting; it is not sufficiently active to be used alone.(5) Greatest activity occurs at less than pH 5; it is inactive above pH 8. Synergistic effects have been reported when combined with benzalkonium chloride, chlorhexidine gluconate or diacetate, polymyxin B sulfate, and phenylmercuric nitrate.(6–10) With either benzalkonium chloride or chlorhexidine, synergistic effects were observed against Pseudomonas aeruginosa and apparently additive effects against Gram-positive organisms. With phenylmercuric nitrate, the effect was additive against Pseudomonas aeruginosa. Additive effects against Pseudomonas cepacia in combination with either benzalkonium chloride or chlorhexidine have also been reported.(11) See also Section 12. Bacteria Fair activity against Gram-positive bacteria; for Staphylococcus aureus, the minimum inhibitory concentration (MIC) may be more than 5 mg/mL. Greater activity is shown against Gram-negative organisms.(12) Typical MIC values are: Salmonella typhi 1.25 mg/mL; Pseudomonas aeruginosa 2.5 mg/mL; Escherichia coli 5.0 mg/mL. Fungi Poor activity against molds and fungi. Spores Inactive, e.g. at 0.6% v/v concentration, reported to be ineffective against spores of Bacillus stearothermophilus at 1008C for 30 minutes. Boiling point 219–2218C Flash point 1028C (open cup) Melting point 278C Partition coefficients Chloroform : water = 15.2; Heptane : water = 0.58; Octanol : water = 21.5. Solubility see Table II.
Phenylethyl alcohol is stable in bulk, but is volatile and sensitive to light and oxidizing agents. It is reasonably stable in both acidic and alkaline solutions. Aqueous solutions may be sterilized by autoclaving. If stored in low-density polyethylene containers, phenylethyl alcohol may be absorbed by the containers. Losses to polypropylene containers have been reported to be insignificant over 12 weeks at 308C. Sorption to rubber closures is generally small. The bulk material should be stored in a well-closed container, protected from light, in a cool, dry place.
Incompatible with oxidizing agents and protein, e.g. serum. Phenylethyl alcohol is partially inactivated by polysorbates, although this is not as great as the reduction in antimicrobial activity that occurs with parabens and polysorbates.(13)
Phenylethyl alcohol is prepared by reduction of ethyl phenylacetate with sodium in absolute alcohol; by hydrogenation of phenylacetaldehyde in the presence of a nickel catalyst; or by addition of ethylene oxide or ethylene chlorohydrin to phenylmagnesium bromide, followed by hydrolysis. Phenylethyl alcohol also occurs naturally in a number of essential oils, especially rose oil.
Phenylethyl alcohol is generally regarded as a nontoxic and nonirritant material. However, at the concentration used to preserve eye-drops (about 0.5% v/v) or above, eye irritation may occur.(14) LD50 (rabbit, skin): 0.79 g/kg(15) LD50 (rat, oral): 1.79 g/kg
Observe normal precautions appropriate to the circumstances and quantity of material handled. Phenylethyl alcohol is combustible when exposed to heat or flame, and emits acrid smoke when heated to decomposition. Eye protection and gloves are recommended.
Included in the FDA Inactive Ingredients Database (nasal, ophthalmic, and otic preparations). Included in nonparenteral medicines licensed in the UK. Included in the Canadian List of Acceptable Non-medicinal Ingredients.
Chlorobutanol.
The EINECS number for phenylethyl alcohol is 200-456-2. The PubChem Compound ID (CID) for phenylethyl alcohol is 6054.