Isomerism

A compound of molecular formula C7H16 shows optical isomerism, compound will be

1. 2,3-dimethylpentane
2. 2,2-dimethylbutane
3. 2-methylhexane
4. none of these

Answer

(1) 2,3-dimethylpentane

Solution

2,3-dimethylpentane: CH3-CH(CH3)- *CH(CH3)-CH2-CH3 ( C7H16)

C-3 carries four different groups: H, CH3, CH(CH3)2 and C2H5 ⇒ chiral carbon ⇒ optically active.

2,2-dimethylbutane is C6H14 and has no chiral carbon.

2-methylhexane: C-2 carries two identical CH3 groups ⇒ no chiral carbon.

∴ The compound is 2,3-dimethylpentane.

Answer: (1)