Benzaldehyde distilled from bitter almond oil, with traces of water.
| IUPAC name
| Systematic IUPAC name
| Other names
|Molar mass||106.12 g/mol|
|Density|| 1.050 g/cm3 (15 °C)|
1.044 g/cm3 (20 °C)
|Melting point||−57.12 °C (−70.82 °F; 216.03 K)|
|Boiling point||178.1 °C (352.6 °F; 451.2 K)|
| 0.3 g/100 ml (20 °C)|
0.695 g/100 ml (25 °C)
|Solubility|| Miscible with diethyl ether, ethanol, methanol|
Soluble in anh. ammonia
|Vapor pressure||1.27 mmHg (25 °C)|
Std enthalpy of
|Safety data sheet||Sigma-Aldrich|
|Flash point||64 °C|
|Lethal dose or concentration (LD, LC):|
LD50 (Median dose)
|1,300 mg/kg (rat, oral)|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Benzaldehyde is an organic chemical compound, the simplest aromatic aldehyde. It has the formula C6H5CHO.
Benzaldehyde will slowly oxidize in air, forming mainly benzoic acid.
- C6H5CHO + ½ O2 → C6H5COOH
Benzaldehyde is difficult to acquire in many countries, due to its use in the manufacturing of illegal drugs. In US it is considered a List I chemical, meaning it cannot be legally purchased without a permit.
A good source of benzaldehyde is bitter almond oil, which is mostly crude benzaldehyde. It can be purified via vacuum distillation or steam distillation in an inert atmosphere. However, keep in mind that since the bitter almond oil is basically crude benzaldehyde, legally there's no distinction between the oil and impure benzaldehyde. In US it's illegal to import bitter almond oil without proper paperwork.
Perhaps the most straightforward preparation of benzaldehyde is through the oxidation of benzyl alcohol in an aqueous solution containing an oxidizer. Benzyl alcohol is slightly soluble in water, although benzaldehyde's solubility in water is much lower. So with good stirring, proper stoichiometry, and plenty of time, it should be easy to produce using anything from household bleach to potassium permanganate. As a bonus, potassium permanganate is reduced to MnO2, which can also oxidize benzyl alcohol, so it's important to take this into account when calculating stoichiometry.
Another more accessible route involves the retro-aldol reaction of cinnaldehyde with sodium carbonate. The yield of this reaction is pretty low, but cinnamon oil is more readily available than bitter almond oil. The reaction takes place in distilled water.
Oxidation of benzyl alcohol with sodium persulfate will give benzaldehyde.
- Flavoring agent
- Make mandelic acid
- Cinnamaldehyde synthesis
- Make bee repellent
Benzaldehyde has low toxicity, though it may be irritant. The lethal dose for a 70 kg adult is considered to be 50 ml. Benzaldehyde does not accumulate in any tissues, and is metabolized and then excreted in urine.
Some studies indicate that benzaldehyde might have anti-cancer properties.
Since benzaldehyde is sensitive to air and light, it should be stored in amber bottles, which are then made air-tight by sealing them with sealing tape, like parafilm. Schlenk flasks can also be used to store this compound.
Benzaldehyde should be mixed with a more volatile solvent and safely burned outside. Another more lengthy route involves oxidation to benzoic acid, which is less volatile and can be safely dumped in trash or poured down the drain.