Question

Which of the following is an example of an asymmetrical ether?

• A. $\mathrm{C_2H_5-O-C_2H_5}$
• B. $\mathrm{CH_3-O-C_2H_5}$
• C. $\mathrm{CH_3-O-CH_3}$
• D. $\mathrm{C_6H_5-O-C_6H_5}$

Hint:

Mixed ether = Asymmetrical ether Example: \[ \mathrm{CH_3-O-C_2H_5} \] Simple ether = Symmetrical ether Example: \[ \mathrm{CH_3-O-CH_3} \]

Answer 1

The Correct Option is B

Concept: Ethers have the general formula \[ \mathrm{R-O-R'} \] where R and R' may be the same or different alkyl/aryl groups.
• If both groups attached to oxygen are identical, the ether is called a symmetrical ether.
• If the two groups attached to oxygen are different, the ether is called an asymmetrical (mixed) ether.

Step 1: Examine Option (1). \[ \mathrm{C_2H_5-O-C_2H_5} \] Both groups are ethyl groups. Hence it is a symmetrical ether.

Step 2: Examine Option (2). \[ \mathrm{CH_3-O-C_2H_5} \] One group is methyl and the other is ethyl. The two groups are different. Therefore it is an asymmetrical ether.

Step 3: Examine Option (3). \[ \mathrm{CH_3-O-CH_3} \] Both groups are methyl groups. Hence it is symmetrical.

Step 4: Examine Option (4). \[ \mathrm{C_6H_5-O-C_6H_5} \] Both groups are phenyl groups. Hence it is symmetrical. Therefore the only asymmetrical ether is \[ \boxed{\mathrm{CH_3-O-C_2H_5}} \] Thus, \[ \boxed{\text{Option (2)}} \]