Benzyl Alcohol

Introduction: What is Benzyl Alcohol?

Benzyl alcohol with chemical formula C6H5CH2OH is an aromatic alcohol. The "Bn" group of benzyls is often abbreviated (not to be mistaken with "Bz" used for benzoyl), and benzyl alcohol is referred to as BnOH. Benzyl alcohol is a colorless liquid with a faint aromatic scent. Its polarity, low toxicity and low vapor pressure make it a useful solvent. Benzyl alcohol has modest water solubility (4 g/100 mL), and alcohol and diethyl ether are miscible. The anion formed by alcohol group deprotonation is called benzylate, or benzyloxide.

IUPAC NAME: Phenyl methanol

Synonyms:

  • Phenylcarbinol

  • Benzenemethanol

Chemical Formula:  C7H8O

Molecular Weight: 108.14 g/mo

Occurrence: Most plants produce benzyl alcohol naturally, and it is commonly found in fruits and teas. It is present also in a variety of essential oils like jasmine, hyacinth, and ylang-ylang. It is also contained in the castoreum of beaver's castor sacs.


Properties

Physical Properties

  • It appears as a colorless liquid

  • It has a slightly aromatic odor.

  • It has a density of 1.044 g cm−3

  • It has a melting point of −15.2 °C (4.6 °F; 257.9 K)

  • Boiling point of benzyl alcohol is 205.3 °C (401.5 °F; 478.4 K)


Solubility

  • It is soluble in water (3.50 g/100 mL (20 °C); 4.29 g/100 mL (25 °C))

  • It is soluble in benzene, methanol, ether, acetone, chloroform, ethanol.


Chemical Properties:

This interacts with carboxylic acids to form esters just like most alcohols. Benzyl esters are common protecting groups in organic synthesis, because they can be extracted by mild hydrogenolysis.

Benzyl alcohol reacts to N-benzylacrylamide by administering acrylonitrile. This is a case in point of a Ritter reaction.


Structure

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Preparation

Benzyl alcohol is manufactured industrially from toluene via the hydrolyzed benzyl chloride.

C6H5CH2Cl + H2O → C6H5CH2OH + HCl

Another route involves benzaldehyde hydrogenation, a by-product of the toluene to benzoic acid oxidation.


Benzyl Alcohol is Synthesized for Laboratory Use:

Benzyl alcohol is also produced by the grignard reaction of phenyl magnesium bromide (C6H5MgBr) with formaldehyde and the benzaldehyde Cannizzaro reaction. The latter also gives benzoic acid, an example of a reaction by organic disproportion.


Uses

Benzyl alcohol is used as a common solvent for the decoration of tints, waxes, shellacs, oils, lacquers, and epoxy resin.

Benzyl alcohol is used in intravenous medicines, cosmetics, and topical products as a bacteriostatic preservative at low concentrations.

5% solution of benzoyl alcohol for the treatment of head lice in people 6 months of age and older. 

It affects the spirals of the louse, preventing them from closing.[9] These then become clogged with water or mineral oil or other matter and cause asphyxiation to cause the insect to die.

Benzyl alcohol is commonly used as the active ingredient in lotion products containing 5 percent benzyl alcohol for curing lice infestations.

It is used to determine the presence of contaminants and quality of quartz. 

FAQ (Frequently Asked Questions)

1. What is Benzyl Alcohol Used for?

Benzyl Alcohol is a colorless liquid with an aromatic scent and a strong burning flavor. It is used as a local anesthetic and to reduce the Lidocaine injection-related pain. This is also used as a medicinal aid in the manufacture of other benzyl products, and in perfumery and flavoring.

2. What Does Benzyl Alcohol Do?

Benzyl Alcohol is an aromatic alcohol that is used as a scent component, preservative, solvent, and viscosity-decreasing agent in a wide variety of cosmetic formulations. Benzyl alcohol is metabolized into Benzoic Acid and interacts with glycine and is excreted in the human body as hippuric acid.

3. Is Benzyl Alcohol Acid or Base?

Benzyl alcohol, also known as benzene methanol or alpha-toluenol, belongs to the class of organic compounds classified as benzyl alcohols. These are organic compounds that contain the substructure for phenyl methanol. Benzyl alcohol is an extremely weak basic compound (essentially neutral), based on its pKa.

4. Is Benzyl Alcohol Natural?

Most plants produce benzyl alcohol naturally, and it is commonly found in fruits and teas. It is present also in a variety of essential oils like jasmine, hyacinth, and ylang-ylang.