Predict the products of the following reactions: (a) excess NH 3 + Ph–CH 2 CH 2 CH 2 Br →

All right. Hi everyone. So for this question, it's asking us to determine the products of the reaction between fennel, ethyl bromide and an excessive amount of ammonia. So recall really quickly when we have an al Kyohei line, such as our final ethyl bromide here and we go ahead and we react that with ammonia. That's going to be what we call the um occupation of a means. Right? It's gonna be an calculation of a means. But recall that the calculation of a means is going to generate a mixture of a means. It's going to be a mixture of primary, secondary and tertiary amines unless we have an excess of ammonia. So if we have an excess of um ammonia in our system, then we're not going to have a mixture. We're going to have just one product of our calculation, which is going to be in this case the mono articulation. So with that being said, let's go ahead and draw out our fennel ethyl bromide here. So we have our final group, two Carbons and A. Brownie. And we are reacting this with an obscene amount of ammonia. So, I'm gonna go ahead and write here NH three in access. So, like I mentioned before, because we have ammonia in such an excess. Um we're only going to see the mono calculation product. If it was not access, then we would see a mixture of primary, secondary and tertiary um a means. So what's going to happen here is that one of the hydrogen of ammonia is going to be replaced by this fennel and our bro me is going to get kicked out. So what I'm gonna do is I'm gonna go ahead and draw out our two Carpentier of the ethyl group and Instead of grooming it's gonna be NH two instead, and this is going to be your final product. So, with that being said, thank you very much for watching and I hope you found this helpful.

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26. Amines

Amine Alkylation

Organic Chemistry

26. Amines

Amine Alkylation

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2:43 minutes

Problem 38a

Textbook Question

Predict the products of the following reactions:
(a) excess NH₃ + Ph–CH₂CH₂CH₂Br →

Verified step by step guidance

Step 1: Recognize the type of reaction. This is a nucleophilic substitution reaction where ammonia (NH₃) acts as the nucleophile and the alkyl bromide (Ph-CH₂CH₂CH₂Br) is the electrophile.

Step 2: Identify the mechanism. Since the alkyl bromide is a primary alkyl halide, the reaction will likely proceed via an SN2 mechanism, where the nucleophile attacks the carbon attached to the bromine, displacing the bromine atom.

Step 3: Write the first substitution step. Ammonia (NH₃) will attack the carbon bonded to the bromine, forming a new bond between the carbon and the nitrogen. This results in the formation of a primary amine (Ph-CH₂CH₂CH₂-NH₂) and the release of bromide ion (Br⁻).

Step 4: Consider the effect of excess NH₃. Since excess ammonia is present, the primary amine product can further react with another molecule of alkyl bromide, leading to the formation of a secondary amine (Ph-CH₂CH₂CH₂-NH-CH₂CH₂CH₂Ph) and so on. This process can continue to form tertiary amines or even quaternary ammonium salts.

Step 5: Summarize the possible products. Depending on the reaction conditions and the amount of excess NH₃, the products can include a primary amine, secondary amine, tertiary amine, or quaternary ammonium salt. The reaction can be controlled to favor specific products by adjusting the stoichiometry and reaction conditions.

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Key Concepts

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

Nucleophilic Substitution

Nucleophilic substitution is a fundamental reaction in organic chemistry where a nucleophile attacks an electrophile, resulting in the replacement of a leaving group. In this case, the bromine atom in Ph-CH2CH2CH2Br acts as the leaving group, while ammonia (NH3) serves as the nucleophile. Understanding this mechanism is crucial for predicting the products of the reaction.

Amine Formation

The reaction of ammonia with alkyl halides typically leads to the formation of amines. In this scenario, the nucleophilic attack by NH3 on the carbon attached to the bromine results in the formation of a primary amine. Recognizing the type of amine produced is essential for accurately predicting the final products of the reaction.

Excess Reagent Effects

Using an excess of a reagent, such as ammonia in this reaction, can influence the outcome by driving the reaction to completion and potentially leading to further reactions. In this case, excess NH3 can lead to the formation of multiple amine products, including secondary and tertiary amines, if the reaction conditions allow for further substitution. Understanding the implications of using excess reagents is vital for predicting all possible products.

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