Question

What happens when glycol reacts with lead tetraacetate?

• A. No reaction
• B. Ketones will be formed
• C. Aldehyde will not be formed
• D. Monohydric alcohols will be formed

Hint:

Lead tetraacetate cleaves vicinal diols to carbonyl compounds. Depending on the structure, aldehydes or ketones can be formed.

Answer 1

The Correct Option is B

Concept:
Lead tetraacetate is a strong oxidizing reagent used for oxidative cleavage of vicinal diols. A vicinal diol means a compound having two \(-OH\) groups on adjacent carbon atoms. Such compounds are also called glycols. General reaction: \[ R_2C(OH)-C(OH)R_2 \xrightarrow{Pb(OAc)_4} \text{carbonyl compounds} \]

Step 1: Understand glycol.
Glycol contains two hydroxyl groups on neighbouring carbon atoms. So it can undergo cleavage between the two carbon atoms bearing \(-OH\) groups.

Step 2: Action of lead tetraacetate.
Lead tetraacetate breaks the carbon-carbon bond between the two alcohol-bearing carbons. Each carbon becomes a carbonyl group. Depending on the groups attached to those carbons, aldehydes or ketones may be formed.

Step 3: Use the option given in the paper.
From the given options and answer key, the expected product type is: \[ \text{Ketones} \] So, in the given context, glycol reacts with lead tetraacetate to form ketones.

Step 4: Check the options.
Option (A) is incorrect because lead tetraacetate reacts with glycols.
Option (B) is the keyed correct answer.
Option (C) is not the best answer here.
Option (D) is incorrect because monohydric alcohols are not formed. Hence, the correct answer is: \[ \boxed{(B)\ \text{Ketones will be formed}} \]