Alcohols, Phenols and Ethers: Physical Properties and Reactions of Phenols (For CBSE, ICSE, IAS, NET, NRA 2022)

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Physical Properties

Similar to alcohols, phenols also have hydrogen atom linked to the electronegative oxygen atom. Thus, phenols also exhibit hydrogen bonding and hence have higher boiling points as compared to the hydrocarbons of similar molecular weight.

Physical Properties

Due to their ability to form hydrogen bonds, phenols show some water solubility. For example, the solubility of phenol is per of water.

Reactions of Phenols

Acidic and Basic Nature

Since phenols are acidic in nature, they are soluble in dilute sodium hydroxide.

Acidic and Basic Nature

Electrophilic Substitution Reactions

In this reaction, an electrophile (electron loving species) attacks the benzene ring and replaces one of its hydrogen atoms. Since the ortho and para positions of the phenol are electron rich, the substitution takes place at these positions. Two such reactions are halogenation and nitration reactions.

Halogenation: Phenol reacts with bromine in aqueous solution to give 2,4, 6- tribromophenol in about 100 % yield.

Electrophilic Substitution Reactions

Bromination can be limited to monobromination to give mainly 4-bromophenol using low temperature and less polar solvent such as carbon di Sulphide. The other product formed in minor quantity is 2-bromophenol.

Nitration: Phenol gives a mixture of 2-nitro and 4-nitrophenols on nitration with dilute nitric acid.

Electrophilic Substitution Reactions
Electrophilic Substitution Reactions

Ethers

  • Ethers are organic compounds in which an oxygen atom is bonded to two alkyl groups or aryl groups. Thus, ethers can be represented as where and may be alkyl or aryl groups.
  • When the two substituent groups are identical, then the ether is called a symmetrical ether, otherwise if these two groups are different, then the ether is known as an unsymmetrical ether.

1.

A symmetrical ether

2.

An unsymmetrical ether

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