Question

Write the structural formula for each of the following.
A $3^{\circ }$ alcohols with the formula $C_4{H}_{8}O$.

Answer 1

Degree of unsaturation:

$\frac{(2n_C+2)-n_H}{2}=\frac{10-8}{2}=1^{\circ }$

$1^{\circ }$ D.U. suggests either unsaturated alcohol or cyclic $3^{\circ }$ alcohol four $C$ atoms; $3^{\circ }$ alcohol cannot be unsaturated, so it is cyclic.