Metamerism is a type of structural isomerism that arises due to the presence of different alkyl groups linked to the same polyvalent functional group.

• It is observed in Ethers ($R-O-R^{\prime }$), Ketones ($R-CO-R^{\prime }$), and Secondary Amines ($R-NH-R^{\prime }$).
• Example: In Ethers ($C_4{H}_{10}O$):
• Diethyl ether: $C_2{H}_5-O-C_2{H}_5$
• Methyl propyl ether: $C{H}_3-O-C_3{H}_7$
• These two are metamers because the groups surrounding the oxygen atom differ.