NEETChemistryHydrocarbons
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): 2,2-Dimethylpropane is readily oxidized to an alcohol by alkaline KMnO ₄ . Reason (R): Alkanes containing a tertiary hydrogen atom are oxidized to corresponding alcohols by potassium permanganate. In the light of the above statements, choose the most appropriate answer from the options given below:
Options
- ABoth Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- BBoth Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- CAssertion (A) is false but Reason (R) is true.
- DAssertion (A) is true but Reason (R) is false.
Correct answer
C. Assertion (A) is false but Reason (R) is true.
Step-by-step solution
Assertion (A) is false. 2,2-Dimethylpropane (neopentane) has the structure C(CH₃)₄ . The central carbon is quaternary ( 4^ ) and is bonded to four methyl groups. It does not possess any tertiary ( 3^ ) hydrogen atom. Therefore, it resists oxidation by alkaline KMnO ₄ . Reason (R) is true. As a general rule, alkanes are inert towards oxidizing agents. However, as an exception, alkanes containing a tertiary hydrogen atom can be oxidized to the corresponding tertiary alcohol by potassium permanganate ( KMnO ₄ ). Thus,