Which of the following is an example of an alkenyl group?
a. ethenyl group
b. phenyl group
c. methylene group
d. more than one correct response
e. no correct response
The Correct Answer and Explanation is:
The correct answer is a. ethenyl group.
Explanation:
Alkenyl groups are derived from alkenes, which are hydrocarbons that contain at least one carbon-carbon double bond (C=C). An alkenyl group specifically refers to a group of atoms that is formed when a hydrogen atom is removed from an alkene. The key feature of alkenyl groups is that they contain a C=C double bond, making them unsaturated, which distinguishes them from alkyl groups (which only have single bonds between carbon atoms).
Let’s analyze the options:
- Ethenyl group (a): This is the correct example of an alkenyl group. The ethenyl group is derived from ethene (C₂H₄), where one hydrogen atom is removed to form the ethenyl group (C₂H₃–). This group contains a carbon-carbon double bond, making it an alkenyl group.
- Phenyl group (b): The phenyl group (C₆H₅–) is derived from benzene (C₆H₆), a cyclic compound with alternating single and double bonds. Although the phenyl group contains carbon-carbon bonds, it is not an alkenyl group because it is derived from an aromatic compound (benzene), not an alkene. Aromatic groups like phenyl do not have the same structure as alkenyl groups, as they involve resonance and delocalized electrons in a ring.
- Methylene group (c): The methylene group (–CH₂–) is a saturated group derived from methane (CH₄) by removing one hydrogen atom. Since it does not contain a carbon-carbon double bond, it is not an alkenyl group. Instead, it is part of an alkyl group.
- More than one correct response (d): Since only the ethenyl group is correct, this option is incorrect.
- No correct response (e): This option is also incorrect because the ethenyl group is indeed an alkenyl group.
In conclusion, the ethernyl group is the only alkenyl group listed in the choices, making it the correct answer.