Question

IUPAC name of the following compound is ___________.

• A. $1$ - chloro-but - $2$ - ene
• B. $1$ - chloro- -but - $3$ - ene
• C. $3$ - chloro- $2$ -methylbut - $1$ - ene
• D. $4$ - chloro-pent - $2$- ene

Answer 1

The correct option is A $1$ - chloro-but - $2$ - ene

The given compound has four carbon atoms, therefore it is assigned the term 'but". There is a chlorine group attached to the first carbon, hence the name '1 chloro'. A double bond exists between the second and third carbon. Hence the name '2 ene'. The IUPAC name is thus given as 1-chloro-but-2-ene.