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Pyridine is less basic than triethylamin...

Pyridine is less basic than triethylamine because :

A

pyridine has aromatic character

B

nitrogen in pyridine is `sp^(2)` hybridised

C

pyridine is a cyclic system

D

in pyridine, lone pair of nitrogen is delocalised.

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The correct Answer is:
To understand why pyridine is less basic than triethylamine, we need to analyze the structural and electronic properties of both compounds. ### Step-by-Step Solution: 1. **Identify the Structures**: - Pyridine is a six-membered aromatic ring containing one nitrogen atom. Its structure can be represented as follows: ``` N / \ C C | | C---C \ / C ``` - Triethylamine is a tertiary amine with the structure: ``` H H \ / H - C - N - C - H / \ H H ``` 2. **Hybridization**: - In pyridine, the nitrogen atom is **sp² hybridized**. This means that one of its p orbitals is involved in the π system of the aromatic ring, which affects the availability of the lone pair of electrons on nitrogen. - In triethylamine, the nitrogen atom is **sp³ hybridized**, which means it has a lone pair of electrons that is more available for donation. 3. **Electronegativity**: - The sp² hybridized nitrogen in pyridine is more electronegative than the sp³ hybridized nitrogen in triethylamine. This increased electronegativity means that the nitrogen in pyridine holds onto its lone pair more tightly, making it less available for protonation (donating to acids). 4. **Electron Donating Groups**: - Triethylamine has three ethyl groups attached to the nitrogen. These groups are electron-donating, which increases the electron density around the nitrogen atom, making it more basic. The electron-donating nature of the ethyl groups enhances the ability of triethylamine to donate its lone pair of electrons. 5. **Resonance and Delocalization**: - In pyridine, the lone pair of electrons on nitrogen is **localized** and not involved in resonance with the aromatic system. This localization reduces its basicity because the lone pair is not available for bonding with protons. - In contrast, the lone pair in triethylamine is free from such delocalization and is readily available for donation. 6. **Conclusion**: - Therefore, the combination of sp² hybridization, increased electronegativity, and the lack of electron-donating groups in pyridine makes it less basic than triethylamine, where the sp³ hybridization and electron-donating ethyl groups enhance its basicity. ### Final Answer: Pyridine is less basic than triethylamine because: - The nitrogen in pyridine is sp² hybridized, making it more electronegative and reducing its ability to donate electrons. - The lone pair of nitrogen in pyridine is localized and not available for bonding, while in triethylamine, the sp³ hybridized nitrogen has a lone pair that is more available for donation due to the presence of electron-donating ethyl groups.
To understand why pyridine is less basic than triethylamine, we need to analyze the structural and electronic properties of both compounds. ### Step-by-Step Solution: 1. **Identify the Structures**: - Pyridine is a six-membered aromatic ring containing one nitrogen atom. Its structure can be represented as follows: ``` N ...
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