Question

For the following compounds, write structural formulas and IUPAC names for all possible isomers having the number of double or triple bond as indicated:
$\left(a\right)C_4{H}_8$ (one double bond)

$\left(b\right)C_5{H}_8$ (one triple bond)

Answer 1

The following structural isomers are possible for $C_4{H}_8$ with one double bond:
Structural formulas of isomers of $C_4{H}_8$

The IUPAC name of Compound
(I) is But-1-ene,
(II) is But-2-ene, and
(III) is 2-Methylprop-1-ene.
Structural formulas of isomers of $C_5{H}_8$

The IUPAC name of Compound
(I) is Pent-1-yne,
(II) is Pent-2-yne, and
(III) is 3-Methylbut-1-yne.