Answer: Na in liquid NH 3.
- A Na in liquid NH<sub>3</sub>
- B KMnO<sub>4</sub>
- C H<sub>2</sub> with Ni
- D Br<sub>2</sub>
Correct answer: A. Na in liquid NH<sub>3</sub>
Explanation: Birch reduction uses sodium or lithium dissolved in liquid ammonia.
Going from a single to a triple bond between carbons increases the s-character of hybridisation (sp³→sp²→sp), shortening the bond and locking the geometry, while increasing π-bond reactivity (alkenes and alkynes readily undergo addition reactions that alkanes don't).
Concept context
The simplest organic compounds made only of carbon and hydrogen. Covers alkanes, alkenes, alkynes, and aromatic compounds like benzene. Learn preparation methods, key reactions, and physical properties.