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Send EmailBenzyl Alcohol, Phenylmethanol, Phenyl Methanol, Hydroxytoluene, Benzal Alcohol, Hydroxymethyl Benzene, 100-51-6
BENZYL ALCOHOL
1. PRODUCT DEFINITION AND CHEMICAL IDENTITY
| Parameter | Description |
|---|---|
| Chemical Name (IUPAC) | Phenylmethanol |
| Common Name | Benzyl Alcohol |
| Other Names | Benzal alcohol, Phenylmethyl alcohol, Hydroxytoluene, Hydroxymethylbenzene, Aromatic alcohol |
| CAS Number | 100-51-6 |
| EC Number | 202-859-9 |
| Molecular Formula | C₇H₈O (C₆H₅CH₂OH) |
| Molecular Weight | 108.14 g/mol |
| Appearance | Clear, colourless liquid |
| Odour | Faint, pleasant aromatic odour |
Note: Benzyl alcohol is an aromatic primary alcohol containing a hydroxymethyl group (-CH₂OH) attached to a benzene ring. It occurs naturally, both free and esterified, in many plants, fruits, teas, and essential oils such as jasmine, hyacinth, and ylang-ylang. Due to its polarity, low toxicity, and low vapour pressure, it is widely used as a versatile solvent, preservative, and chemical intermediate in pharmaceutical, cosmetic, and industrial applications. It also exhibits local anaesthetic properties.
2. PHYSICAL AND CHEMICAL PROPERTIES
| Property | Value / Description |
|---|---|
| Physical form | Clear, colourless liquid |
| Melting point | −15.2 °C |
| Boiling point | 205.3 °C |
| Flash point (closed cup) | 93 °C |
| Autoignition temperature | 436 °C |
| Density (20 °C) | 1.044 g/cm³ |
| Vapour pressure (20 °C) | 0.013 kPa (0.1 mmHg) – low volatility |
| Vapour density (air=1) | 3.7 |
| Solubility in water (20 °C) | ~4 g/100 mL (moderately soluble) |
| Solubility in organic solvents | Miscible in all proportions with alcohol, diethyl ether, acetone, chloroform, and many organic solvents |
| Viscosity (25 °C) | 5.5 mPa·s |
| Refractive index (n²⁰/D) | 1.539 – 1.541 |
| pH (aqueous solution) | Neutral (~7) |
| Stability | Stable under normal conditions; may slowly oxidize to benzaldehyde upon prolonged exposure to air and light. Reacts with strong oxidizing agents. |
3. FUNCTIONAL PROPERTIES AND APPLICATION AREAS
| Property / Function | Description |
|---|---|
| Solvent | Due to its high polarity, low toxicity, and low vapour pressure, it is an excellent solvent for many organic substances such as resins, paints, inks, cellulose esters, and gelatin. It is also used in epoxy and polyurethane systems. |
| Preservative (Antimicrobial Agent) | Exhibits broad-spectrum antimicrobial activity, effective against bacteria, yeasts, and moulds. Used as a preservative in pharmaceutical injectable solutions, cosmetic products, and personal care formulations. It is FDA-approved. |
| Chemical Intermediate | A fundamental building block in the synthesis of benzyl esters, benzyl ethers, benzylamine, and many other organic compounds. Used in the production of esters like benzyl acetate and benzyl benzoate, which are widely used in the fragrance and flavour industry. |
| Local Anaesthetic | Exhibits mild local anaesthetic properties. It is added to formulations to reduce pain associated with injectable medications like lidocaine. It is also found in teething gels and topical antipruritic products. |
| Viscosity Modifier | Functions as a reactive diluent in epoxy resin systems, reducing viscosity for ease of application and improving mechanical properties. |
| Fragrance and Flavour Component | Contributes to floral notes like jasmine and hyacinth; used as a fixative and softener in perfume and flavour formulations. |
4. TYPICAL SPECIFICATIONS (Industrial and Pharmaceutical Grade)
| Parameter | Specification |
|---|---|
| Purity (%) | ≥ 99.0 (industrial); ≥ 99.5 (pharmaceutical) |
| Water Content (%) | ≤ 0.2 |
| Benzaldehyde Content (%) | ≤ 0.1 |
| Acidity (as benzoic acid, %) | ≤ 0.05 |
| Colour (Pt-Co, APHA) | ≤ 20 |
5. USAGE RATES (Sectoral)
| Sector / Application | Typical Usage / Concentration |
|---|---|
| Pharmaceutical (Preservative) | 0.5 – 2% (in injectable and topical solutions) |
| Cosmetics & Personal Care (Preservative) | 0.5 – 1.5% |
| Epoxy Resin (Reactive Diluent) | 5 – 20% |
| Paints, Varnishes & Inks (Solvent) | 2 – 15% |
| Perfume & Flavour (Fixative/Solvent) | 1 – 10% |
| Cleaning Products | 1 – 5% |
6. ADVANTAGES AND DISADVANTAGES
| ✅ Advantages | ❌ Disadvantages |
|---|---|
| Broad-spectrum preservative efficacy; effective against bacteria, yeasts, and moulds | May cause skin and eye irritation at high concentrations |
| Low toxicity profile; FDA-approved | Contraindicated in neonates and premature infants due to risk of "gasping syndrome" |
| Low vapour pressure; does not evaporate quickly, providing a long-lasting effect | May cause allergic contact dermatitis in sensitive individuals |
| Versatile solvent; dissolves many polar and non-polar substances | Its characteristic, though mild, aromatic odour may be undesirable in some applications |
| Naturally occurring; suitable for natural cosmetic formulations | Reacts with strong oxidizers; storage conditions must be observed |
7. ALTERNATIVES AND COMPARISON
| Alternative | Comparison with Benzyl Alcohol |
|---|---|
| Phenoxyethanol | Similar preservative profile; weaker activity against yeasts and moulds compared to benzyl alcohol, but effective over a wider pH range. Often combined with benzyl alcohol. |
| Ethyl Alcohol (Ethanol) | Better solvent and disinfectant; however, it is much more volatile and dries the skin. Not as effective as a preservative compared to benzyl alcohol. |
| Propylene Glycol | Better humectant and solvent; its preservative efficacy is much weaker than benzyl alcohol. |
| Parabens (Methylparaben, Propylparaben) | Strong preservatives; however, consumer perception is negative due to their potential endocrine-disrupting effects. Benzyl alcohol is considered a "cleaner label" alternative. |
| Benzoic Acid / Sodium Benzoate | Common food preservative; only effective at acidic pH (pH < 5). Benzyl alcohol works over a wider pH range. |
8. SAFETY, STORAGE, AND TRANSPORT
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GHS Classification (CLP Regulation):
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Signal Word: Warning
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Hazard Statements:
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H302: Harmful if swallowed.
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H315: Causes skin irritation.
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H319: Causes serious eye irritation.
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H335: May cause respiratory irritation.
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Precautionary Statements: P261, P264, P271, P280, P302+P352, P304+P340, P305+P351+P338, P312, P332+P313, P337+P313.
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Special Warning (Pharmaceutical Use): Contraindicated in premature infants and neonates due to the risk of "gasping syndrome" (metabolic acidosis, respiratory depression).
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Storage:
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Store in a cool (<25 °C), dry, and well-ventilated area in tightly sealed, original packaging.
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Protect from light; prolonged exposure to light can lead to oxidation and the formation of benzaldehyde.
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Keep away from strong oxidizing agents.
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Personal Protective Equipment (PPE): Chemical-resistant gloves (nitrile, neoprene), safety goggles. Use a respirator with an organic vapour cartridge when working with large quantities or in case of inadequate ventilation.
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Transport: Not classified as a dangerous good for transport.
9. FREQUENTLY ASKED QUESTIONS
Q1: Why is benzyl alcohol used in injectable medications?
Benzyl alcohol is used in injectable solutions both as a preservative (to prevent microbial growth in multi-dose vials) and as a mild local anaesthetic. It helps reduce pain associated with injections of certain medications like lidocaine.
Q2: Is benzyl alcohol natural?
Yes, benzyl alcohol occurs naturally in many plants, fruits, teas, and essential oils (jasmine, hyacinth, ylang-ylang). Commercially, it can be both isolated from natural sources and produced synthetically. Naturally sourced benzyl alcohol is preferred in natural cosmetic formulations.
Q3: Why is it used as a preservative in cosmetics?
Benzyl alcohol exhibits broad-spectrum antimicrobial activity against bacteria, yeasts, and moulds. It is considered a "cleaner label" alternative compared to controversial preservatives like parabens, and its use is permitted by many certified natural/organic cosmetic standards.
Q4: What is the shelf life of benzyl alcohol?
When stored under proper conditions (cool, dry, protected from light, sealed packaging), the shelf life is at least 24 months. Exposure to light can cause it to slowly oxidize to benzaldehyde, leading to a characteristic almond-like odour.
Q5: Which materials are incompatible with benzyl alcohol?
It can react violently with strong oxidizers (nitric acid, hydrogen peroxide, potassium permanganate). It may dissolve or soften some types of plastics (polystyrene, polycarbonate); glass, HDPE, or stainless steel equipment is preferred for storage and handling.
10. QUICK REFERENCE TABLE
| Property | Value |
|---|---|
| CAS | 100-51-6 |
| Formula | C₆H₅CH₂OH |
| Molecular Weight | 108.14 g/mol |
| Appearance | Clear, colourless liquid |
| Odour | Faint, pleasant aromatic |
| Melting Point | −15.2 °C |
| Boiling Point | 205.3 °C |
| Density | 1.044 g/cm³ |
| Main Uses | Solvent, preservative, chemical intermediate, local anaesthetic |
