Question

Gabriel's synthesis is used frequently for the preparation of which of the following? 

• A. \(1^{st}\) amines
• B. \(1^{st}\) alcohols
• C. \(3^{rd}\) amines
• D. \(3^{rd}\) alcohols

Hint:

Gabriel's synthesis is a useful method for synthesizing primary amines from alkyl halides by the use of phthalimide. It does not produce secondary or tertiary amines.

Answer 1

The Correct Option is A

Gabriel's synthesis is a chemical reaction used to synthesize primary amines (\(1^{st}\) amines). This process typically involves the following steps:

1. Phthalimide is treated with a base to form the phthalimide anion.

2. The phthalimide anion then undergoes nucleophilic substitution with an alkyl halide. This step introduces the alkyl group to the nitrogen atom.

3. Hydrolysis (with acid or base) of the alkylated phthalimide leads to the cleavage of the phthalimide group, resulting in the formation of a primary amine.

Gabriel's synthesis is specifically designed to prepare primary amines, avoiding the formation of secondary and tertiary amines, which can occur in other synthetic methods. Therefore, among the given options, Gabriel's synthesis is used for the preparation of:

• Primary amines (\(1^{st}\) amines)

Answer 2

Gabriel's synthesis is a well-known method in organic chemistry, primarily utilized for the preparation of primary amines (\(1^{st}\) amines). This method involves the following key steps:

1. Formation of phthalimide anion: The process begins with the conversion of phthalimide to its anionic form using a strong base such as potassium hydroxide (\(KOH\)) or sodium hydroxide (\(NaOH\)).

2. Alkylation: The phthalimide anion is then alkylated using an alkyl halide (\(R-X\)), where \(R\) is the alkyl group and \(X\) is the halogen, typically bromide or iodide. This results in the formation of a N-alkylphthalimide.

3. Hydrolysis: The N-alkylphthalimide undergoes hydrolysis, commonly with hydrazine (\(N_2H_4\)), to yield the primary amine and phthalic acid as a by-product.

This synthesis method is advantageous because it avoids the formation of secondary and tertiary amines, making it selective for primary amines. Hence, the correct option is:

1^st amines