Question

# The conformations of n-butane, commonly known as eclipsed, gauche and anti conformations can be interconverted by :a.) Rotation around $C - H$ bond of a methyl groupb.) Rotation around $C - H$ bond of a methylene groupc.) Rotation around $C1 - C2$ linkaged.) Rotation around $C2 - C3$ linkage

Verified
129k+ views
Hint : The conformations of butane can be interconverted only by rotation around the central carbon atoms in butane.

Butane is a form of carbon molecule that exists in three forms when we see molecules in Newman projection or sawhorse projection.
Conformational isomerism is a form of stereoisomerism in which the isomers can be interconverted just by rotations about single bonds. These conformations change only by single carbon carbon rotation. In butane, four such conformations are possible which are fully eclipsed, eclipsed, gauche and anti.

The three conformations of butane given in question i.e. eclipsed, anti and gauche can be interconverted by rotation around $C2 - C3$ linkage.
Thus, option d.) is the correct answer.
The rotations around C-H in methyl will not show any difference. SO, option a.) and b.) can not be the answer.