Question

Identify X, Y and Z in the following reactions sequence:

• A.

  

• B.

  

• C.

  

• D.

  

Hint:

For alcohols, Jones reagent (CrO\(_3\)) is commonly used to oxidize primary alcohols to carboxylic acids. The decarboxylation step requires NaOH and CaO to remove the carboxyl group.

Answer 1

The Correct Option is D

In the given sequence: - \( X = \text{Jones reagent} \), which is a strong oxidizer used to oxidize alcohols to aldehydes or carboxylic acids. Thus, \( C_6H_5CH_2CH_2OH \) is oxidized to \( C_6H_5CH_2COOH \) (benzoic acid). - \( Y = \text{NaOH, CaO} \) indicates a decarboxylation reaction, where the carboxyl group is removed, leading to the formation of a hydrocarbon, \( C_6H_5CH_3 \) (toluene). Thus, the correct sequence is:

Answer 2

In the given reaction sequence, we are starting from an alcohol (C₆H₅CH₂CH₂OH) and ending with an aromatic hydrocarbon (C₆H₅CH₃). Let us analyze each step in detail:

1. Step 1: Oxidation of Alcohol to Carboxylic Acid
The compound C₆H₅CH₂CH₂OH (phenylethanol) undergoes oxidation. To convert a primary alcohol to a carboxylic acid, we use a strong oxidizing agent such as the Jones reagent (CrO₃ in aqueous H₂SO₄). This converts the alcohol into C₆H₅CH₂COOH (phenylacetic acid).
So,
X = Jones reagent

2. Step 2: Decarboxylation of the Carboxylic Acid
In the second step, C₆H₅CH₂COOH undergoes decarboxylation. This is typically carried out using soda lime (a mixture of NaOH and CaO) with heat. Decarboxylation removes the COOH group and replaces it with a hydrogen atom. Hence,
C₆H₅CH₂COOH → C₆H₅CH₃ (toluene)

So,
Y = NaOH, CaO, Δ
Z = C₆H₅CH₃

Final Answer:
X = Jones reagent
Y = NaOH, CaO, Δ
Z = C₆H₅CH₃