Benzyl alcohol

• BPBenzyl Alcohol
• JPBenzyl Alcohol
• Ph. Eur.Benzyl Alcohol
• USP–NFBenzyl Alcohol

Alcohol benzylicus; benzenemethanol; α-hydroxytoluene; phenylcarbinol; phenylmethanol; α-toluenol; E1519

Phenylmethanol · [100-51-6]

UNII LKG8494WBH · PubChem CID 244

C7H8O · 108.14

Antimicrobial preservative, Solvent, humectant

Typical concentrations: up to 2% preservative · Dosage forms: Sterile (parenteral/ophthalmic), Semi-solid, Liquid

Widely used as an antimicrobial preservative in multidose injections (commonly about 0.9–2% v/v, as in bacteriostatic water and saline for injection), and in oral, topical and vaginal preparations. It is also used as a solvent and co-solvent, for example in oily injections and in some topical products, and it has weak local anaesthetic properties. In foods and cosmetics it is used as a flavour and fragrance ingredient and as a solvent.

A clear, colourless, oily liquid with a faint aromatic odour and a sharp, burning taste.

Boiling point

≈ 205 °C

Melting point

≈ −15 °C

Density

≈ 1.04–1.05 g/cm³ at 20 °C

Solubility

soluble in water (about 1 in 25 at 25 °C); miscible with ethanol, ether, chloroform and fixed and volatile oils

Refractive index

≈ 1.538–1.541

Oxidises slowly in air to benzaldehyde and benzoic acid. Aqueous solutions may be sterilised by filtration or autoclaving, although some loss by volatilisation can occur. Store in an airtight container, protected from light, in a cool, dry place; metal and certain plastic containers should be avoided.

Incompatible with oxidising agents and strong acids. Its antimicrobial activity is reduced by nonionic surfactants such as polysorbate 80. It is sorbed by natural rubber, neoprene and butyl rubber closures and may be lost through low-density polyethylene; polypropylene, glass and coated closures are preferred.

Made mainly by hydrolysis of benzyl chloride with aqueous sodium carbonate or sodium hydroxide, or by hydrogenation of benzaldehyde, followed by distillation. It occurs naturally as esters in many essential oils.

Metabolised to benzoic acid, which is conjugated and excreted as hippuric acid. At preservative concentrations it is well tolerated in adults, but it has been associated with a fatal 'gasping syndrome' in premature and newborn infants given relatively large amounts in flush solutions, so preparations containing it should not be used in neonates, and EU labelling sets warnings for young children and for large volumes. Hypersensitivity reactions occasionally occur.

Observe normal precautions for the quantity handled. It irritates the eyes and skin; gloves and eye protection are recommended, and it should be used with adequate ventilation.

Permitted in foods in the USA as a synthetic flavouring substance and accepted in Europe as a carrier solvent for food flavourings (E1519). Included in the FDA Inactive Ingredient Database (dental, intramuscular, intravenous and subcutaneous injections, oral, topical and vaginal preparations) and in parenteral and non-parenteral medicines licensed in Europe.

Benzoic acid; benzyl benzoate; chlorobutanol; phenoxyethanol; phenylethyl alcohol.

Benzyl alcohol is most active at acidic pH and has relatively weak activity against some moulds and Gram-negative organisms at the usual 1% level. Benzaldehyde formed by oxidation has a bitter-almond odour and should be limited, particularly in injections.