Write the following name reaction: (i) Gabriel phthalimide reaction. (ii) Hoffman bromamide reaction.

Let's delve into two important name reactions in organic chemistry: the Gabriel phthalimide reaction and the Hofmann bromamide reaction. Both of these reactions are significant for synthesizing amines, but they operate through different mechanisms and starting materials.

Gabriel Phthalimide Reaction

The Gabriel phthalimide reaction is a method for synthesizing primary amines from phthalimide. This reaction is particularly useful because it allows for the formation of amines without the risk of over-alkylation, which can occur in other methods.

Mechanism Overview

The process begins with phthalimide, which is treated with a strong base, typically potassium hydroxide (KOH) or sodium hydride (NaH), to deprotonate the nitrogen atom. This generates a nucleophilic phthalimide anion that can then undergo nucleophilic substitution with an alkyl halide.

• The reaction can be summarized as follows:
• Phthalimide + Base → Phthalimide anion
• Phthalimide anion + Alkyl halide → N-alkyl phthalimide
• N-alkyl phthalimide + Hydrolysis → Primary amine + Phthalic acid

After the alkylation step, the N-alkyl phthalimide is hydrolyzed, usually by boiling with aqueous acid, to yield the desired primary amine and phthalic acid as a byproduct. This reaction is particularly advantageous because it allows for the selective formation of primary amines, avoiding the formation of secondary or tertiary amines.

Hofmann Bromamide Reaction

The Hofmann bromamide reaction is another valuable method for synthesizing amines, specifically primary amines, from amides. This reaction is notable for its ability to convert amides into amines while also reducing the carbon chain length by one carbon atom.

Mechanism Breakdown

The reaction begins with an amide, which is treated with bromine (Br2) in the presence of a strong base, such as sodium hydroxide (NaOH). The mechanism involves several key steps:

• Formation of N-bromoamide: The amide reacts with bromine to form an N-bromoamide intermediate.
• Deprotonation: The strong base deprotonates the N-bromoamide, generating a reactive intermediate.
• Elimination: The intermediate undergoes rearrangement, leading to the loss of carbon dioxide (CO2) and the formation of the primary amine.

The overall reaction can be summarized as:

Amide + Br2 + Base → Primary amine + Byproducts (such as NaBr and CO2)

This reaction is particularly useful in organic synthesis because it allows for the conversion of stable amides into more reactive amines, facilitating further chemical transformations.

Comparative Insights

Both reactions are essential tools in organic chemistry for synthesizing primary amines, but they differ in their starting materials and mechanisms:

• The Gabriel phthalimide reaction starts with phthalimide and is ideal for avoiding over-alkylation.
• The Hofmann bromamide reaction begins with amides and effectively shortens the carbon chain while producing amines.

Understanding these reactions not only enhances your grasp of amine synthesis but also illustrates the diverse strategies chemists employ to manipulate organic compounds. Each reaction has its unique advantages, making them valuable in various synthetic pathways.