Question

Which of the following compounds is least likely to give effervescence of CO$_2$ in presence of aq. NaHCO$_3$?

• A.
• B.
• C.
• D.

Hint:

In reactions with NaHCO\(_3\), look for acidic functional groups (like -COOH or -OH) that readily react to release CO\(_2\). Nitrogenous compounds without strong acidic groups generally do not react.

Answer 1

The Correct Option is D

To determine which compound least readily produces CO₂ effervescence with aqueous NaHCO₃, one must consider the acidic properties of each substance. NaHCO₃ typically reacts with acids to release CO₂. Consequently, compounds lacking acidity or possessing very weak acidity will not liberate CO₂ when exposed to NaHCO₃.

Step-by-step Analysis:

1. Ascertain the acidity of each compound. Only acidic compounds will react with NaHCO₃ to yield CO₂.
   • A carboxylic acid (COOH) functional group or a phenolic group generally exhibits acidity.
   • Alcohols and ethers typically do not react with NaHCO₃ due to their insufficient acidity.
2. Evaluate each provided option:
   • Option 1 contains a carboxylic acid group, which is acidic and will react with NaHCO₃ to produce CO₂.
   • Option 2 also features a carboxylic acid, exhibiting similar reactivity to Option 1.
   • Option 3 likely includes a phenol, which can be acidic and may produce CO₂ gas upon reaction with NaHCO₃.
   • Option 4 consists of an ether group, which is non-acidic and thus unlikely to react with NaHCO₃.
3. Conclusion: The compound characterized solely by an ether group (Option 4) is least likely to generate effervescence with NaHCO₃.

Correct Answer Explanation: Option 4, the compound with the ether group, is the correct answer because ethers lack acidic protons that can react with NaHCO₃ to produce CO₂ gas. Therefore, it is the least likely to cause effervescence.