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Which is the best leaving group ?...

Which is the best leaving group ?

A

`- overset(oplus)(N) -= N`

B

`OH^(-)`

C

`NH_(2)^(-)`

D

`CH_(3) COO^(-)`

Text Solution

AI Generated Solution

The correct Answer is:
To determine which is the best leaving group among the given options, we need to analyze the stability of the leaving groups after they depart from the substrate. A better leaving group is one that forms a more stable species after leaving. ### Step-by-Step Solution: 1. **Identify the Leaving Groups**: The options provided are: - A) N2+ - B) OH− - C) NH2− - D) CH3COO− 2. **Analyze Each Leaving Group**: - **Option A: N2+ (Nitrogen gas)**: When N2+ leaves, it forms a neutral nitrogen gas (N2), which is very stable and inert. The departure of N2+ does not leave any charge, making it a very favorable leaving group. - **Option B: OH− (Hydroxide ion)**: When OH− leaves, it forms a negatively charged hydroxide ion. The negative charge on OH− is not stabilized by any electron-withdrawing groups, making it a less favorable leaving group compared to N2+. - **Option C: NH2− (Amide ion)**: Similar to OH−, when NH2− leaves, it also forms a negatively charged amide ion. The negative charge on NH2− is not stabilized, making it a poor leaving group. - **Option D: CH3COO− (Acetate ion)**: When CH3COO− leaves, it forms a negatively charged acetate ion. However, the acetate ion is resonance-stabilized, which makes it a better leaving group than OH− and NH2−, but still not as good as N2+. 3. **Compare the Stability of the Leaving Groups**: - N2+ forms a stable, neutral gas. - OH− and NH2− both leave as negatively charged ions that are not stabilized. - CH3COO− is stabilized by resonance, but still carries a negative charge. 4. **Conclusion**: Since N2+ leaves as a neutral and stable molecule, it is the best leaving group among the options provided. ### Final Answer: The best leaving group is **Option A: N2+**. ---
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