Consider these reasons for base stability when answering 13-15. 1. Delocalizatio
ID: 483387 • Letter: C
Question
Consider these reasons for base stability when answering 13-15. 1. Delocalization of charge through a system (stable if it withdraws, unstable if it donates) 2. ization of charge through m system (stable if it withdraws. unstable if it donates) 3. through size (arger delocalizes better) 4. Delocalization through shape (rounder delocalizes better) 5 negative charge on electronegative atom). e Equilibrium Reaction NH2 NH duoc thru S&R; OH de loc. 13. For reaction I, what factor is most important in determining the equilibrium favorability? B) 2 A) 1 C) 3 D) 4 14. For reaction ll, what factor is most important in determining the equilibrium favorability? E) 5 B) 2 A) 1 15. For reaction III, what factor is most important in determining the equilibrium favorability? C) 3 E) 5 D) 4 A) 1Explanation / Answer
Stability of base
1. A base is more stable as charged species If the charge is delocalised in the sigma-bond system, that is the negative charge is pulled inside such that the charge becomes more stable. On the other hand donating effect will make the charge less stable.
2. Similarly for a pi-bond system, again the delocalisation of charge would make the charged species more stable whereas the donating effect would destabilise the already electron rich charged species.
3. As the size goes up, more valence orbitals are available for delocalisation of the extrac electron in the form of charge and thus the stability of base goes up.
4. As the shape becomes more compact (rounder), the base species can easily solvate in solution which makes its stability increase. the charge is equally distributed on all sides.
5. A higher electronegatve atom with a negative charge is more stable than a less electronegative atom with negative charge. the electron pull is greater in the former case and this makes the base on more electronegatuve atom more stable.