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The acidic character of alcohols is due ...

The acidic character of alcohols is due the polar nature of O-H bond. An e releasing group `(- CH_(3) -C_(2)H_(5))` increases e density on oxygen thus decreasing the acidity while e withdrawing group increases the acidity.
Which among the following is most acidic

A

B

C

D

Text Solution

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The correct Answer is:
To determine which among the given compounds is the most acidic, we need to analyze the effects of substituents on the acidity of alcohols and phenols. The acidic character of alcohols and phenols is influenced by the nature of the substituents attached to the aromatic ring or the alcohol group. ### Step-by-Step Solution: 1. **Understanding Acidity in Alcohols and Phenols:** - The acidic character of alcohols is primarily due to the polar nature of the O-H bond. When an alcohol loses a proton (H⁺), it forms an alkoxide ion, which is stabilized by the substituents on the molecule. 2. **Effect of Electron Releasing Groups:** - Electron releasing groups (like -CH₃ or -C₂H₅) increase the electron density on the oxygen atom. This makes it less likely for the alcohol to lose a proton, thus decreasing its acidity. 3. **Effect of Electron Withdrawing Groups:** - Conversely, electron withdrawing groups (like -NO₂) decrease the electron density on the oxygen atom. This stabilization of the negative charge on the alkoxide ion makes it easier for the alcohol to lose a proton, thus increasing its acidity. 4. **Comparing Acidity of Phenols:** - Among the compounds given, we need to compare the acidity of phenol and its derivatives with electron withdrawing groups. - **Phenol** itself has moderate acidity. - **Nitrophenols** (ortho, meta, and para) have -NO₂ groups which are strong electron withdrawing groups. 5. **Ranking the Acidity of Nitrophenols:** - The para-nitro group is the most effective in stabilizing the negative charge due to resonance and inductive effects, making **para-nitrophenol** the most acidic. - The ortho-nitro group can also stabilize the negative charge but is slightly less acidic due to intramolecular hydrogen bonding, which hinders the release of the proton. - The meta-nitro group is the least effective in stabilizing the negative charge compared to ortho and para positions. 6. **Conclusion:** - Based on the analysis, the order of acidity is: - **Most Acidic:** Para-nitrophenol - Ortho-nitrophenol - Meta-nitrophenol - Least Acidic: Phenol ### Final Answer: The most acidic compound among the given options is **para-nitrophenol**.
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The acidic character of alcohols is due the polar nature of O-H bond. An e releasing group (- CH_(3) -C_(2)H_(5)) increases e density on oxygen thus decreasing the acidity while e withdrawing group increases the acidity. Which among the following is a better proton acceptor

The acidic character of alcohols is due the polar nature of O-H bond. An e releasing group (- CH_(3) -C_(2)H_(5)) increases e density on oxygen thus decreasing the acidity while e withdrawing group increases the acidity. Which is the strongest acid among:

Knowledge Check

  • Which of the following compounds are more acidic than H_(2)O ?

    A
    `CH_(3)-OH`
    B
    `H-overset(overset(O)(||))(C)-OH`
    C
    `CH_(3)-ddot(N)H_(2)`
    D

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