Textbook Question
What alkyl bromide would you use in a Gabriel synthesis to prepare each of the following amines?
a. pentylamine
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26. Amines
Gabriel Synthesis
2:26 minutesProblem 38d
Textbook Question
What alkyl bromide would you use in a Gabriel synthesis to prepare each of the following amines?
d. cyclohexylamine
Verified step by step guidance1
Understand the Gabriel synthesis: It is a method used to prepare primary amines by reacting a phthalimide anion with an alkyl halide, followed by hydrolysis or hydrazinolysis to release the amine.
Identify the target amine: The target amine in this case is cyclohexylamine, which has the structure C₆H₁₁NH₂. This means the alkyl group attached to the nitrogen is a cyclohexyl group.
Determine the required alkyl bromide: In the Gabriel synthesis, the alkyl bromide provides the alkyl group that will eventually be attached to the nitrogen. Therefore, the alkyl bromide should have a cyclohexyl group attached to the bromine atom. The structure of the alkyl bromide would be cyclohexyl bromide (C₆H₁₁Br).
Write the reaction sequence: The phthalimide anion (generated by treating phthalimide with a strong base) reacts with cyclohexyl bromide in an SN2 reaction to form an N-alkylphthalimide intermediate.
Complete the synthesis: The N-alkylphthalimide intermediate is then hydrolyzed (using aqueous acid or base) or treated with hydrazine to release the primary amine, cyclohexylamine, as the final product.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Gabriel Synthesis
Gabriel synthesis is a method used to prepare primary amines from alkyl halides. It involves the use of phthalimide, which reacts with a base to form a phthalimide salt. This salt then undergoes nucleophilic substitution with an alkyl halide, leading to the formation of the desired amine after hydrolysis. This method is particularly useful for avoiding the formation of secondary or tertiary amines.
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Alkyl Bromides
Alkyl bromides are organic compounds containing a bromine atom attached to an alkyl group. They are commonly used as electrophiles in nucleophilic substitution reactions due to the polar C-Br bond, which makes the carbon susceptible to attack by nucleophiles. In the context of Gabriel synthesis, the choice of alkyl bromide is crucial as it determines the structure of the resulting amine.
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Cyclohexylamine
Cyclohexylamine is a primary amine derived from cyclohexane, characterized by the presence of an amine group (-NH2) attached to a cyclohexyl group. In Gabriel synthesis, to produce cyclohexylamine, one would need to use a suitable alkyl bromide that can provide the cyclohexyl group. The correct choice of alkyl bromide ensures that the final product is a primary amine, which is essential for the desired outcome.
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