Show how you can synthesize the following compounds starting with benzene, toluene, and alcohols containing no more than four carbon atoms as your organic starting materials. Assume that para is the major product (and separable from ortho) in ortho, para mixtures.
(c) N-ethyl-N-propylbutan-2-amine

Verified step by step guidance

Step 1: Begin with the synthesis of butan-2-amine. Start with a suitable alcohol containing no more than four carbons, such as 2-butanol. Convert 2-butanol to 2-bromobutane using phosphorus tribromide (PBr₃) or hydrogen bromide (HBr). Then, perform an SN2 reaction with ammonia (NH₃) to replace the bromine atom with an amine group, yielding butan-2-amine.

Step 2: Protect the amine group in butan-2-amine to prevent unwanted side reactions during subsequent steps. This can be done by reacting the amine with a protecting group, such as benzyl chloride, to form an N-benzyl derivative.

Step 3: Synthesize the ethyl and propyl groups to attach to the nitrogen atom. Use ethyl bromide (C₂H₅Br) and propyl bromide (C₃H₇Br) as alkylating agents. Perform successive alkylation reactions on the protected amine to introduce the ethyl and propyl groups, forming N-ethyl-N-propylbutan-2-amine.

Step 4: Remove the protecting group from the nitrogen atom to regenerate the free amine. For example, if a benzyl protecting group was used, catalytic hydrogenation (H₂ with Pd/C) can be employed to remove it.

Step 5: Purify the final product, N-ethyl-N-propylbutan-2-amine, by separation techniques such as distillation or chromatography to ensure the desired compound is isolated in high purity.

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Key Concepts

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

Electrophilic Aromatic Substitution (EAS)

Electrophilic Aromatic Substitution is a fundamental reaction in organic chemistry where an electrophile replaces a hydrogen atom on an aromatic ring, such as benzene. This reaction is crucial for synthesizing complex organic molecules from simpler aromatic compounds. Understanding the mechanism of EAS, including the role of activating and deactivating groups, is essential for predicting the products formed when starting with benzene or toluene.

Alkylation Reactions

Alkylation reactions involve the introduction of alkyl groups into a molecule, often through the use of alkyl halides and nucleophiles. In the context of synthesizing amines, alkylation can be used to build up the carbon chain of the target compound, such as N-ethyl-N-propylbutan-2-amine. Mastery of these reactions is necessary to manipulate the structure of starting materials like alcohols and toluene to achieve the desired amine product.

Amine Synthesis

Amine synthesis refers to the various methods used to create amines, which are organic compounds containing nitrogen. In this case, the target compound is a secondary amine, which can be synthesized through the alkylation of ammonia or primary amines. Understanding the reactivity of amines and the conditions required for their formation is vital for successfully synthesizing N-ethyl-N-propylbutan-2-amine from the specified starting materials.

Show how you can synthesize the following compounds starting with benzene, toluene, and alcohols containing no more than four carbon atoms as your organic starting materials. Assume that para is the major product (and separable from ortho) in ortho, para mixtures.(c) N-ethyl-N-propylbutan-2-amine