Q.60. - Organic Chemistry

Question

Question: Classify each pair of compounds as constitutional isomers or identical molecules.

a. 

b.

Step-by-Step Solution

Answer

Answer

1. The given compounds are identical.
2. The given compounds are constitutional isomers. 

Step 1: Constitutional isomers

Constitutional isomers have the same number of atoms of each element but differ in the connectivities of those atoms. 

For example, 1-butene and 2-butene have the same molecular formula  $C_4{H}_8$ but are completely different in terms of the bonding of atoms.

Constitutional isomers

Step 2: Identical molecules

Identical molecules have the same molecular formula, sequence, connectivities, and arrangement of atoms in space.

Step 3: Re-draw the structures

Re-draw the given structures along with the bonds from the given Newman structures. Check for isomerism.

Step 4: Isomerism in the given compounds

a. Re-drawing the structure from the given Newman projections, you get:

Re-drawn structures

Since the IUPAC names of the two structures are the same, the two compounds are identical. 

 

b. Re-drawing the skeletal structure from the given Newman projections, you get:

Re-drawn structures

Since the given compounds are different in bonding, the compounds are constitutional isomers.