JEE Chemistry 2023 Question with Solution

Given: The order of basic strength in aqueous medium for methyl-substituted amines is to be identified.

Find: The correct order among the given options.

In aqueous medium, the basic strength of amines depends on:

1. Electron density on the nitrogen atom due to the inductive effect of methyl groups.
2. Solvation effect, which stabilizes the conjugate acid after accepting a proton.

• Dimethylamine $\mathrm{Me}_2\mathrm{NH}$: The best combination of inductive effect and solvation, making it the most basic.
• Methylamine $\mathrm{MeNH}_2$: Slightly less basic due to less inductive effect but better solvation.
• Trimethylamine $\mathrm{Me}_3\mathrm{N}$: Weaker basicity because bulky groups hinder solvation.
• Ammonia $\mathrm{NH}_3$: Lowest basicity due to the absence of inductive effect.

Therefore, the order is

$$\mathrm{Me}_2\mathrm{NH} > \mathrm{MeNH}_2 > \mathrm{Me}_3\mathrm{N} > \mathrm{NH}_3$$

So, the correct option according to the extracted working is A.

Note: The solution says "The Correct Option is C", but the worked explanation clearly concludes the order matching Option A. Hence the worked solution is taken as authoritative.