Question

Complete each synthesis by giving missing starting material, reagent, or products: (I) \(\text{CH}_3\text{CH}_3 + \text{KMnO}_4, \text{KOH} \longrightarrow \text{?}\)
(II) CH2 −→ ? −→ CHO
(III)\(C_6H_6 + Pd - BaSO_4^{ −}→ \ ?\)

Hint:

Potassium permanganate is a strong oxidizing agent and is effective for oxidizing alkyl groups to carboxylic acids.

Answer 1

Reactions:

(i) Ethylbenzene (\( \text{C}_6\text{H}_5\text{CH}_2\text{CH}_3 \)) undergoes oxidation with potassium permanganate (\( \text{KMnO}_4 \)) and potassium hydroxide (\( \text{KOH} \)). This reaction converts the methyl group on ethylbenzene into a carboxyl group, yielding acetic acid (\( \text{CH}_3\text{COOH} \)).

(ii) The CH\(_2\) group undergoes oxidation to form an aldehyde. This can be achieved using a mild oxidizing agent like PCC (Pyridinium chlorochromate), which selectively oxidizes alcohols to aldehydes without further oxidation. The final product is an aldehyde, such as acetaldehyde (\( \text{CH}_3\text{CHO} \)).

(iii) Benzene (\( \text{C}_6\text{H}_6 \)) undergoes hydrogenation in the presence of palladium (Pd) supported on barium sulfate (\( \text{BaSO}_4 \)) as a catalyst. The reaction adds hydrogen atoms to the benzene ring, converting it into cyclohexane. This process is called catalytic hydrogenation.