Which of the following amines can be prepared by Gabriel phthalimide reaction?

• A. neopentylamine
• B. n-butylamine
• C. triethylamine
• D. t-butylamine

The Gabriel phthalimide reaction is a well-known method for synthesizing primary amines from phthalimide derivatives. This reaction is particularly useful because it allows for the selective formation of primary amines without the risk of forming secondary or tertiary amines. To determine which of the given amines can be prepared using this method, let’s break down the options one by one.

Understanding the Gabriel Phthalimide Reaction

The Gabriel reaction involves the nucleophilic substitution of a phthalimide with an alkyl halide. The general steps are as follows:

• Phthalimide is treated with a strong base, such as potassium hydroxide (KOH), to form the phthalimide anion.
• This anion then acts as a nucleophile and attacks an alkyl halide, resulting in the formation of a N-alkyl phthalimide.
• Finally, hydrolysis of the N-alkyl phthalimide yields the corresponding primary amine.

Analyzing the Options

Now, let’s evaluate each of the amines listed in your question:

A. Neopentylamine

Neopentylamine is a primary amine with the structure (CH3)4C(NH2). To synthesize it via the Gabriel reaction, we would need to use a neopentyl halide. However, neopentyl halides are known to undergo elimination reactions rather than substitution due to steric hindrance. Therefore, neopentylamine cannot be prepared using the Gabriel reaction.

B. n-Butylamine

n-Butylamine is a straightforward primary amine (C4H11NH2). It can be synthesized using the Gabriel reaction by reacting phthalimide with butyl bromide (or another butyl halide). This reaction proceeds smoothly, making n-butylamine a suitable candidate for preparation via the Gabriel method.

C. Triethylamine

Triethylamine is a tertiary amine (N(CH2CH3)3). The Gabriel reaction specifically produces primary amines, and attempting to synthesize triethylamine would not be feasible through this method. Therefore, triethylamine cannot be prepared using the Gabriel reaction.

D. t-Butylamine

t-Butylamine is also a tertiary amine ((CH3)3CNH2). Similar to triethylamine, the Gabriel reaction cannot yield tertiary amines, as it only produces primary amines. Hence, t-butylamine cannot be synthesized using this reaction.

Final Thoughts

From the analysis above, the only amine that can be prepared via the Gabriel phthalimide reaction is n-butylamine. The other options, neopentylamine, triethylamine, and t-butylamine, cannot be synthesized using this method due to their structural characteristics and the nature of the reaction. This highlights the importance of understanding the underlying mechanisms when selecting appropriate synthetic routes in organic chemistry.