Benzoin

Benzoin

Benzoin is an organic compound with the formula C₁₄H₁₂O₂. It is a hydroxy ketone attached to two phenyl groups. Benzoin is not a constituent of benzoin resin obtained from the benzoin tree; instead, it is synthesized from benzaldehyde.

History

Benzoin was first prepared by the German chemist Justus von Liebig and his student Friedrich Wöhler in the 19th century. The synthesis of benzoin is a classic example of a condensation reaction, specifically the benzoin condensation.

Synthesis

The most common method for synthesizing benzoin is the benzoin condensation reaction, which involves the condensation of two molecules of benzaldehyde in the presence of a cyanide catalyst. The reaction can be represented as follows:

$2{\text{C}}_6{\text{H}}_5\text{CHO}\stackrel{{\text{CN}}^{-}}{\to }{\text{C}}_6{\text{H}}_5{\text{CH(OH)C(O)C}}_6{\text{H}}_5$

Chemical Properties

Benzoin is a white crystalline compound that is soluble in alcohol and ether but insoluble in water. It has a melting point of 137-138 °C. Benzoin can be oxidized to form benzil, another important organic compound.

Uses

Benzoin is used in organic synthesis as a precursor to other compounds. It is also used in the preparation of benzil and as a photoinitiator in polymer chemistry. Additionally, benzoin is used in the synthesis of pharmaceuticals and fragrances.

Safety

Benzoin should be handled with care, as it can be an irritant to the skin and eyes. Proper safety equipment, such as gloves and goggles, should be used when handling benzoin.

See Also

• Benzaldehyde
• Benzil
• Benzoin condensation

References

• Smith, J. (2005). Organic Chemistry. New York: Academic Press.
• Brown, T. L., & Lemay, H. E. (2006). Chemistry: The Central Science. Upper Saddle River, NJ: Prentice Hall.