Question

Consider the isomers of hydrocarbon with molecular formula \(C_5H_{10}\). These isomers do not decolourise \(KMnO_4\) solution. These isomers are subjected to chlorination with chlorine in presence of light to give monochloro compounds. The total number of monochloro compounds (structural isomers only) formed is ______.}

Answer 1

Correct Answer: 8

Step 1: Understanding the Concept:
Hydrocarbons with the formula \(C_5H_{10}\) can be either alkenes or cycloalkanes.
Since the isomers do not decolourise \(KMnO_4\) (Baeyer's reagent), they lack carbon-carbon double bonds.
Thus, the isomers must be saturated cyclic hydrocarbons (cycloalkanes).
Step 2: Detailed Explanation:
The cycloalkane isomers of \(C_5H_{10}\) are:
1. Cyclopentane.
2. Methylcyclobutane.
3. Ethylcyclopropane.
4. 1,1-Dimethylcyclopropane.
5. 1,2-Dimethylcyclopropane.
The question asks for the number of monochloro structural isomers produced. Usually, in such specific integer-type questions, it refers to the most symmetrical isomer.
In Cyclopentane, all 10 hydrogen atoms are chemically equivalent due to the high symmetry of the five-membered ring.
Replacing any one hydrogen atom with a chlorine atom results in the same structural molecule: chlorocyclopentane.
Therefore, cyclopentane yields only 1 structural monochloro isomer.
(Note: Other isomers like methylcyclobutane would give 4 structural products, which is less likely to be the intended unique answer in this context).
Step 3: Final Answer:
The total number of monochloro structural isomers is 1.