Table of contents

1. A Review of General Chemistry5h 5m
2. Molecular Representations1h 14m
3. Acids and Bases2h 46m
4. Alkanes and Cycloalkanes4h 17m
5. Chirality3h 39m
6. Thermodynamics and Kinetics1h 22m
7. Substitution Reactions1h 48m
8. Elimination Reactions2h 30m
9. Alkenes and Alkynes2h 9m
10. Addition Reactions3h 19m
11. Radical Reactions1h 58m
12. Alcohols, Ethers, Epoxides and Thiols2h 42m
13. Alcohols and Carbonyl Compounds2h 17m
14. Synthetic Techniques1h 26m
15. Analytical Techniques:IR, NMR, Mass Spect7h 3m
16. Conjugated Systems6h 13m
17. Ultraviolet Spectroscopy51m
18. Aromaticity2h 34m
19. Reactions of Aromatics: EAS and Beyond5h 1m
20. Phenols55m
21. Aldehydes and Ketones: Nucleophilic Addition4h 56m
22. Carboxylic Acid Derivatives: NAS2h 51m
23. The Chemistry of Thioesters, Phophate Ester and Phosphate Anhydrides1h 10m
24. Enolate Chemistry: Reactions at the Alpha-Carbon1h 53m
25. Condensation Chemistry2h 9m
26. Amines1h 43m
27. Heterocycles2h 0m
28. Carbohydrates5h 53m
29. Amino Acids4h 20m
30. Peptides and Proteins2h 42m
31. Catalysis in Organic Reactions1h 30m
32. Lipids 2h 50m
33. The Organic Chemistry of Metabolic Pathways2h 52m
34. Nucleic Acids1h 32m
35. Transition Metals6h 14m
36. Synthetic Polymers1h 49m

10. Addition Reactions

Epoxide Reactions

Organic Chemistry

10. Addition Reactions

Epoxide Reactions

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12:34 minutes

Problem 36b

Textbook Question

The existence of the NIH shift was established by determining the major product obtained from rearrangement of the following arene oxide, in which a hydrogen has been replaced by a deuterium.
b. What would be the major product if the carbocation forms phenol by losing H⁺ or D⁺, rather than by going through the NIH shift?

Verified step by step guidance

Step 1: Analyze the structure of the arene oxide provided in the image. The molecule contains a benzene ring with an epoxide group attached, where one hydrogen is replaced by deuterium (D). Additionally, there is a methyl group (-CH3) attached to the benzene ring.

Step 2: Understand the reaction conditions. The presence of HB+ indicates acidic conditions, which can lead to the opening of the epoxide ring. This process typically involves protonation of the oxygen atom in the epoxide, making it more electrophilic and susceptible to nucleophilic attack.

Step 3: Consider the mechanism of ring opening. Protonation of the epoxide oxygen leads to the formation of a carbocation intermediate. The carbocation can undergo rearrangement via the NIH shift, where the deuterium (D) migrates to the adjacent carbon, or it can directly lose H+ or D+ to form phenol.

Step 4: If the carbocation loses H+ or D+ without undergoing the NIH shift, the major product will be phenol. The loss of H+ or D+ will result in the formation of a hydroxyl group (-OH) on the benzene ring at the position where the epoxide was originally attached.

Step 5: Predict the major product. If the carbocation loses H+, the phenol product will retain the deuterium (D) at its original position. If the carbocation loses D+, the phenol product will have hydrogen (H) at the position where deuterium was originally located. The major product depends on which proton (H+ or D+) is preferentially lost during the reaction.

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Key Concepts

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

NIH Shift

The NIH shift refers to a specific rearrangement mechanism in organic chemistry where a hydrogen atom is replaced by a deuterium atom during the transformation of an arene oxide to a phenolic compound. This process involves the migration of a hydrogen atom to a neighboring carbon atom, resulting in a new carbocation intermediate. Understanding this shift is crucial for predicting the products of reactions involving arene oxides.

Carbocation Stability

Carbocation stability is a key concept in organic chemistry that describes the relative stability of positively charged carbon species. Factors influencing stability include the degree of substitution (primary, secondary, tertiary), resonance effects, and inductive effects from nearby atoms or groups. A more stable carbocation is more likely to form and dictate the pathway of the reaction, impacting the final product.

Deprotonation Mechanism

Deprotonation is the process of removing a proton (H+ or D+) from a molecule, which can lead to the formation of a stable product such as phenol. In the context of the question, understanding how a carbocation can lose a proton directly to form phenol, rather than undergoing a rearrangement like the NIH shift, is essential for predicting the major product of the reaction. This mechanism highlights the importance of reaction pathways in organic synthesis.

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