Answer to Question #53796 in Organic Chemistry for tarun jain

Question

Why is ethyne more acidic than ethane?

Answer 1

Terminal alkynes (ethyne) have carbon atoms with sp-hybridization, and alkanes (ethane) contain carbons with sp3 – hybridization. Since s-character of hybride orbitals is larger by 25% for ethyne than for ethane, sp – orbital is closer to carbon nuclei than sp3 – one. Therefore, due to the most electrostatic stabilization of the lone pair, the most stable carboanion is formed for ethyne upon deprotonation. Taking into account that higher stability of carboanion indicates higher acidity of initial neutral compound, ethyne is more acidic than ethane.