The CORRECT order of basicity for the following compounds is
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In compounds containing nitrogen, the availability of the lone pair on nitrogen determines its basicity. Nitrogen atoms involved in aromaticity are less basic than those where the lone pair is free.
Step 1: Understanding basicity.
The basicity of a compound is determined by the availability of its lone pair of electrons to accept a proton (H+). The more readily a compound can donate its lone pair to a proton, the stronger the base. The electron-donating effects of substituents (such as NH2) affect the basicity.
Step 2: Analyzing the structures.
- Compound I has a nitrogen attached to a benzene ring (pyridine), and the lone pair on nitrogen is involved in the aromaticity of the ring, making it less basic.
- Compound II has a nitrogen attached to a two-ring structure (pyrrole), with the nitrogen’s lone pair somewhat localized and not participating in aromaticity, making it more basic.
- Compound III is a simple nitrogen-containing ring (imidozole), where the nitrogen’s lone pair is highly available, but the presence of an electronegative group slightly lowers its basicity compared to II.
Step 3: Conclusion.
The correct order of basicity is (C): II \(>) I \(>) III.
