Predict the major product when each reagent reacts with ethylene oxide. (d) PhNH 2 (aniline) (e) KCN (potassium cyanide) (f) NaN 3 (sodium azide)

Hello, everyone. Today, we have the following problem ignoring stereo chemistry, draw the products formed from a reaction of 23 dimethyl oxy with each of the following. So first, we have our potassium azide and this will dissociate into positive potassium ions and negative negatively charged azide, which is a strong nuclear file. So what will occur is we will have a nucleic attack. So if we draw out what Azai actually looks like it has the following structure, we have our nucleic attack and this could be on either carbon oxide because both are equally substituted. This will force a ring opening and give us the following product. So we will have our negatively charged oxygen and this product will actually just exist as a salt. And that is because we have no other reactants with it. So this is our answer for part A part B says to react this oxer rain molecule with cyclo hexamine. As we did with the previous reaction, we will have a nucleic attack. So we will have our cyclohexane structure, which is a cyclic structure composed of six carbons. Then we will have our mean bound to it. And this is a rather neutral nucleo file, but it can still perform a nucleic attack on either carbon of the oxer, forcing the ring to be opened. And this will yield us this intermediate here, it has a positively charged nitrogen and a negatively charged oxygen within the same molecule. Now, to stabilize this structure, we can have a two in one such that we can get rid of both charges. So we can form an intra molecular dep protonation using a negatively charged oxygen and deproteinate the positively charged nitrogen such that we can be yielded the following alcohol product. So that's our answer for part B in the last but not least, we have sodium cyanide reacting with this oxer rain. And sodium cyanide associates into positively charged sodium ions and a negatively charged cyanide molecule. So will we react our oxer rain with that negatively charged cyanide, which has the following structure. This will be a nucleic attack at either carbon or the oxer R opening that ring and yielding us this following salt product. And this will be the salt product because we don't have any other reactants. And so with that, we have our answers overall, I hope has helped. And until next time.

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10. Addition Reactions

Epoxide Reactions

Organic Chemistry

10. Addition Reactions

Epoxide Reactions

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3:41 minutes

Problem 26d,e,f

Textbook Question

Predict the major product when each reagent reacts with ethylene oxide.
(d) PhNH₂ (aniline)
(e) KCN (potassium cyanide)
(f) NaN₃ (sodium azide)

Verified step by step guidance

Step 1: Understand the structure and reactivity of ethylene oxide. Ethylene oxide is a three-membered cyclic ether (epoxide) with significant ring strain, making it highly reactive towards nucleophiles. The nucleophile will attack the less sterically hindered carbon of the epoxide, leading to ring opening.

Step 2: Analyze the reagent in part (d), PhNH2 (aniline). Aniline is a nucleophile due to the lone pair on the nitrogen atom. The nitrogen will attack the less hindered carbon of ethylene oxide, opening the ring and forming a β-amino alcohol. The product will have the structure PhNH-CH2-CH2OH.

Step 3: Analyze the reagent in part (e), KCN (potassium cyanide). The cyanide ion (CN⁻) is a strong nucleophile. It will attack the less hindered carbon of ethylene oxide, opening the ring and forming a β-cyano alcohol. The product will have the structure HO-CH2-CH2-CN.

Step 4: Analyze the reagent in part (f), NaN3 (sodium azide). The azide ion (N3⁻) is a nucleophile. It will attack the less hindered carbon of ethylene oxide, opening the ring and forming a β-azido alcohol. The product will have the structure HO-CH2-CH2-N3.

Step 5: Summarize the general mechanism for all three reactions. In each case, the nucleophile attacks the less hindered carbon of the epoxide, leading to ring opening and the formation of a β-substituted alcohol. The specific substituent depends on the nucleophile used (PhNH for aniline, CN for potassium cyanide, and N3 for sodium azide).

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Key Concepts

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

Epoxide Reactivity

Epoxides, such as ethylene oxide, are three-membered cyclic ethers that are highly reactive due to the strain in their ring structure. They can undergo nucleophilic ring-opening reactions, where a nucleophile attacks the less hindered carbon atom, leading to the formation of alcohols or other functional groups. Understanding the mechanism of this reaction is crucial for predicting the products formed when different nucleophiles react with epoxides.

Nucleophiles

Nucleophiles are species that donate an electron pair to form a chemical bond in a reaction. In the context of the question, aniline (PhNH2), potassium cyanide (KCN), and sodium azide (NaN3) act as nucleophiles that will attack the epoxide. The strength and nature of the nucleophile influence the reaction pathway and the final product, making it essential to consider their reactivity and sterics when predicting outcomes.

Product Prediction

Predicting the major product of a reaction involves understanding the regioselectivity and stereochemistry of the nucleophilic attack on the epoxide. Factors such as the nucleophile's structure, the reaction conditions, and the stability of the resulting intermediates play a significant role in determining which product is favored. Analyzing these aspects allows for accurate predictions of the major products formed in the reactions with ethylene oxide.

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