Predict the product(s) of the reactions shown.
(i)

Verified step by step guidance

Step 1: Identify the starting material as phthalimide, which is a cyclic imide derived from phthalic acid.

Step 2: Recognize the first reagent, nBuBr (n-butyl bromide), which is an alkyl halide. This suggests an alkylation reaction where the nitrogen atom of the phthalimide will act as a nucleophile.

Step 3: Understand that the phthalimide nitrogen will attack the n-butyl bromide, displacing the bromide ion and forming N-butylphthalimide.

Step 4: Note the second step involves KOH and hydrazine (H2NNH2) under heat (Δ). This indicates a Gabriel synthesis, where the phthalimide is converted to a primary amine.

Step 5: In the Gabriel synthesis, hydrazine reacts with N-butylphthalimide to release the primary amine, n-butylamine, and form phthalhydrazide as a byproduct.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Nucleophilic Substitution Reaction

Nucleophilic substitution is a fundamental class of reactions in organic chemistry where a nucleophile selectively bonds with or attacks the positive or partially positive charge of an atom or a group of atoms to replace a leaving group. In the given reaction, nBuBr (n-butyl bromide) acts as the alkylating agent, where the bromide ion is the leaving group, and the nitrogen atom in the imide acts as the nucleophile.

Gabriel Synthesis

Gabriel synthesis is a method used to synthesize primary amines from primary alkyl halides. The reaction involves the use of phthalimide, which is deprotonated to form a nucleophilic phthalimide anion that reacts with an alkyl halide. In this reaction, the phthalimide is alkylated by nBuBr, and subsequent hydrazinolysis releases the primary amine, n-butylamine.

Hydrazinolysis

Hydrazinolysis is a chemical reaction where hydrazine is used to cleave a bond, often in the context of removing protecting groups. In the Gabriel synthesis, hydrazinolysis is used to convert the N-alkylphthalimide intermediate into the corresponding primary amine. Here, hydrazine reacts with the alkylated phthalimide to release n-butylamine and phthalhydrazide as a byproduct.

Related Practice

Textbook Question

The Gabriel synthesis is most frequently done with 1° alkyl halides. Why is it less successful with more substituted halides?

1057

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Textbook Question

Suggest reagents to carry out the following transformations. Some may require more than one step.

(b)

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Textbook Question

Predict the product(s) of the reactions shown.