Question

In the given reactions identify the reagent A and reagent B

• A. $A-\text{CrO}_3 \quad B-\text{CrO}_3$
• B. $A-\text{CrO}_3 \quad B-\text{CrO}_2\text{Cl}_2$
• C. $A-\text{CrO}_2\text{Cl}_2 \quad B-\text{CrO}_2\text{Cl}_2$
• D. $A-\text{CrO}_2\text{Cl}_2 \quad B-\text{CrO}_3$

Answer 1

Answer: (B)

$A-\text{CrO}_3 \quad B-\text{CrO}_2\text{Cl}_2$

Answer 2

Step 1: The reaction starts with toluene, which is oxidized by reagent A (CrO3) in acetic anhydride (CH3CO)2O. This oxidation step is known as the Etard reaction, where toluene is converted into benzylidene diacetate as an intermediate.

Step 2: The intermediate benzylidene diacetate is then treated with reagent B (CrO2Cl2), followed by hydrolysis (H2O+) to yield benzaldehyde (C6H5CHO).

Thus, the correct reagents are A-CrO3 and B-CrO2Cl2, which is represented by option (2).