Question

$ n- $ propyl alcohol and isopropyl alcohol can be chemically distinguished by which reagent :-

• A. $PCl_5$
• B. reduction
• C. oxidation with potassium dichromate
• D. ozonolysis

Answer 1

The Correct Option is C

To distinguish between n-\text{propyl alcohol} and \text{isopropyl alcohol}, we will explore the given options and apply the appropriate chemical test.

Option Analysis:

• PCl_5: This reagent is used for converting alcohols into alkyl chlorides, but it doesn't help in distinguishing between primary and secondary alcohols like n-\text{propyl alcohol} and \text{isopropyl alcohol}.
• Reduction: Through this process, the alcohol would be converted to the corresponding alkane, but it does not allow us to distinguish between the two types of alcohols.
• Ozonolysis: This method is used primarily in the cleavage of alkenes and would not provide distinguishing results with these alcohols.
• Oxidation with potassium dichromate: Potassium dichromate is an oxidizing agent that can differentiate between primary and secondary alcohols.

Reasoning:

When oxidized with potassium dichromate, the reactions vary depending on the type of alcohol:

• n-propyl alcohol (\text{C}_3\text{H}_7\text{OH}): This is a primary alcohol. Primary alcohols are oxidized first to aldehydes and then to carboxylic acids. Therefore, n-\text{propyl alcohol} will be oxidized to propionaldehyde and further to propionic acid.
• Isopropyl alcohol (\text{CH}_3\text{CHOH}\text{CH}_3): This is a secondary alcohol. Secondary alcohols are oxidized to ketones. Thus, isopropyl alcohol will be oxidized to acetone.

The difference in oxidation products allows us to distinguish between the two alcohols. Thus, the correct answer is oxidation with potassium dichromate.