Target Exam

CUET

Subject

Chemistry

Chapter

Organic: Amines

Question:

Read the passage carefully and answer the questions.

Amines are considered as derivatives of ammonia obtained by replacement of hydrogen atoms with alkyl or aryl groups. In nature they occur among proteins, vitamins, alkaloids and hormones. These can be primary, secondary or tertiary depending on the number of hydrogen groups replaced. They can be prepared from nitro compounds, alkyl halides, nitriles, amides etc. Due to unshared pair of electrons they behave as Lewis bases. Influence of the number of hydrogen atoms at nitrogen atom is displayed in physical properties such as solubility, boiling point and chemical reactions including basicity. Basic character of amines is expressed in terms of their $K_b$ and $pK_b$ values. Three classes of amines can be distinguished with p-toluene sulphonyl chloride which reacts with primary and secondary amines. Amino group when attached to benzene ring behaves as an activating and ortho para directing group.

Which reagent is used for the conversion of acetamide into ethylamine?

Options:

$H_2/Ni$

$LiAlH_4/H_2O$

Na/Ethanol

$LiAlH_4/ether$

Correct Answer:

$LiAlH_4/ether$

Explanation:

The correct answer is Option (4) → $LiAlH_4/ether$ **

The conversion of acetamide (CH₃CONH₂) to ethylamine (CH₃CH₂NH₂) is a reduction reaction where the carbonyl group (C=O) in the amide is reduced to a methylene group (-CH₂-), yielding a primary amine.

  • Reaction: CH₃CONH₂ + 4[H] → CH₃CH₂NH₂ + H₂O
  • This is achieved using LiAlH₄ in ether as the reducing agent, followed by hydrolysis (H₃O⁺ workup).