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Phenyl Groups In Organic Compounds

by Paul Petersen

Organic Nomenclature

In the field of organic chemistry phenyl group or phenyl ring is a cyclic compound with the chemical formula C6H5. The phenyl group is almost the same as benzene ring with the less of one hydrogen atom, which is replaced by other functional groups. In a phenyl group, there are six carbon atoms arranged themselves in a hexagonal planar ring. Out of six carbon atoms, five carbon atoms are bonded to two hydrogen atoms and the sixth carbon atom bonded with functional groups. Phenyl groups are aromatic compounds with alternating single and double bonds having the same bond length between all the carbon atoms.

Difference Between The Phenyl Group And Benzene Compound


Benzene Phenyl Group
The chemical formula of benzene is C6H6. The chemical formula of phenyl compound is C6H5.
Benzene is a compound which has all paired electrons in it. A phenyl group is a radical since it has unpaired electrons in it.
Structure of benzene Structure of phenyl compound

Physical Properties of Phenyl Group

  • Chemical formula – C6H5
  • Molecular mass – 77.106 g/mol
  • Density – 1.248 g/dm3
  • Melting point – (-300C)
  • Boiling point – 232.20C
  • Odour and appearance – Phenyl smell and white crystalline solid
  • Less soluble in water.

The distinction between phenyl compounds and aryl compounds must be known to have a clear picture regarding phenyl compounds.

Aryl Compounds Phenyl Compounds
Always have an aromatic ring. They are formed by the ring of benzene by removing one hydrogen atom from it.
Aryl group is obtained by loss of one H atom from an aromatic compound. A phenyl group is obtained by removing one H atom from an aromatic compound.
The number of carbon atoms depends on the type of aryl group present. There are six carbon atoms present in the phenyl compound.
Examples: Toluyl group, naphthyl group. Examples: Phenol, toluene.


Preparation Of Some Phenyl Compounds

1. Toluene compound

Tolueneis an aromatic compound with the chemical formula C6H5CH3.  It is a colourless water-soluble compound having a paint-like smell. In other words, toluene is a monosubstituted chemical compound in which -CH3 group is attached to phenyl compound.

Toluene is a product of petroleum compounds. It can be synthesized by treating benzene with methyl chloride in the presence of Lewis acid (AlCl3).

Uses Of Toluene

  • Toluene is used as a solvent in many applications.
  • Used in internal combustion engines (Gasoline fuel).
  • It is used as a precursor to many other chemical compounds.

2. Phenols

Phenol is an aromatic compound with molecular formula C6H5OH. It is a volatile white crystalline solid consisting of a phenyl group bonded to a hydroxyl functional group.

(1) The direct oxidation of benzene to phenol theoretically observed but practically not commercialized.

C6H6 + O → C6H5OH.

(2) Chlorobenzene is treated with sodium hydroxide at a temperature of 623K and 300 atm pressure. A sodium phenoxide is formed followed by acidification that gives phenol.

Application Of Phenols

  • Phenols are used as an antiseptic.
  • Phenol derivatives are used in the preparation of many cosmetics such as hair colouring, sunscreen lotion etc.