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

7. Substitution Reactions

Substitution Comparison

Organic Chemistry

7. Substitution Reactions

Substitution Comparison

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4:37 minutes

Problem 77e,f

Textbook Question

Draw the substitution products for each of the following reactions; if the products can exist as stereoisomers, show what stereoisomers are obtained:
e. 1-bromo-2-butene + CH₃O⁻
f. 1-bromo-2-butene + CH₃OH

Verified step by step guidance

Step 1: Analyze the substrate (1-bromo-2-butene) and the nucleophile/base in each reaction. For part (e), the nucleophile is CH3O− (a strong nucleophile and base), and for part (f), the nucleophile is CH3OH (a weak nucleophile and solvent).

Step 2: Determine the mechanism for each reaction. For part (e), the strong nucleophile CH3O− suggests an SN2 mechanism, where the nucleophile attacks the carbon bonded to the bromine in a single concerted step. For part (f), the weak nucleophile CH3OH suggests an SN1 mechanism, where the bromine leaves first to form a carbocation intermediate, followed by nucleophilic attack.

Step 3: For part (e), in the SN2 mechanism, the nucleophile CH3O− will attack the carbon bonded to the bromine from the opposite side (backside attack), leading to inversion of configuration at the carbon center. Since the carbon is sp2 hybridized (planar) in 1-bromo-2-butene, stereoisomerism is not a concern here.

Step 4: For part (f), in the SN1 mechanism, the bromine leaves first, forming a carbocation intermediate. The carbocation is planar and can be attacked by CH3OH from either side, leading to the formation of two stereoisomers (R and S configurations) if the carbon is chiral after substitution.

Step 5: Draw the products for each reaction. For part (e), the product will be 2-methoxy-2-butene. For part (f), the products will be two stereoisomers of 2-methoxy-2-butene if chirality is present. Ensure to show the stereochemistry explicitly in the products for part (f).

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Key Concepts

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

Nucleophilic Substitution Reactions

Nucleophilic substitution reactions involve the replacement of a leaving group in a molecule by a nucleophile. In the context of the given reactions, the nucleophile (CH3O− or CH3OH) attacks the carbon atom bonded to the bromine atom, leading to the formation of new products. Understanding the mechanism, whether it follows an SN1 or SN2 pathway, is crucial for predicting the structure and stereochemistry of the products.

Stereochemistry

Stereochemistry refers to the study of the spatial arrangement of atoms in molecules and how this affects their chemical behavior. In the reactions provided, the formation of stereoisomers is possible due to the presence of chiral centers in the products. Recognizing how the nucleophile approaches the substrate can help determine the stereochemical outcomes, including whether enantiomers or diastereomers are formed.

Alkenes and Electrophilic Addition

Alkenes, such as 1-bromo-2-butene, can undergo electrophilic addition reactions where the double bond reacts with electrophiles. In the context of the reactions, the alkene can react with the nucleophiles to form substitution products. Understanding the reactivity of alkenes and the nature of the electrophiles involved is essential for predicting the products and their stereochemical configurations.

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