Question

What is the IUPAC name of the following?

A. Ethenyl cyclopentane
B. cyclopentyl ethene
C. cyclopentyl ethylene
D. vinyl cyclopentane

Answer 1

Functional group with the formula $- C{H_2} = CH -$ is ethenyl or vinyl basically vinylic carbon atom is one of the two carbon atoms that share the double bond. By removing 1 hydrogen from ethylene we get $- C{H_2} = CH -$ which is a vinyl group but allylic carbon is the carbon atom next to the double-bonded carbon atom. The allylic carbon is $s{p^3}$hybridized and is bonded to $s{p^2}$a hybridized carbon atom by a single bond but the vinylic carbon is $s{p^2}$ hybridized.

Complete answer:
The IUPAC naming of any compound involves identifying the longest and continuous carbon chain (The continuous form can be a chain or a ring pattern.) and naming the continuous carbon chain according to the numeric word root. Then the next step involves identifying the parent functional group and numbering it with the highest order of precedence. Identification of the side chain and the type of bond present and then adding the suitable suffix/prefix is the next step.
The compound has the formula ${C_7}{H_{12}}$.

The structure has a cyclic ring which has 5 carbon atoms so it can be named cyclopentane.
The structure has $- CH = C{H_2}$ a functional group which is vinyl. So the chemical compound has a vinyl functional group and the IUPAC name of the compound can be written as vinyl cyclopentane.

Therefore the correct answer is option D.

Note:
Ring consisting of five carbon atoms attached to two hydrogen atoms above and below the plane is the Cyclopentane. It is in the class of cycloalkanes. Cyclopentane can be obtained in the presence of alumina, cracking cyclohexane at a high temperature and pressure.