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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3:44 minutes

Problem 110c,d

Textbook Question

Draw the substitution products for each of the following S_N2 reactions. If the products can exist as stereoisomers, show which stereoisomers are formed:
c. (3R,4R)-3-bromo-4-methylhexane + CH₃O^-
d. (3R,4S)-3-bromo-4-methylhexane + CH₃O^-

Verified step by step guidance

Step 1: Identify the type of substitution reaction. Since CH3O- is a strong nucleophile and a strong base, the reaction is likely to proceed via an SN2 mechanism. In SN2 reactions, the nucleophile attacks the carbon attached to the leaving group (bromine) from the opposite side, leading to inversion of configuration at the carbon center.

Step 2: Analyze the stereochemistry of the starting material for part (a). The compound (3R, 4R)-3-bromo-4-methylhexane has the bromine atom on the 3rd carbon in the R configuration and a methyl group on the 4th carbon in the R configuration. When CH3O- attacks the 3rd carbon, the configuration at this carbon will invert to S due to the backside attack characteristic of SN2 reactions.

Step 3: Draw the product for part (a). After the substitution, the bromine is replaced by the methoxy group (-OCH3), and the stereochemistry at the 3rd carbon is inverted to S. The 4th carbon retains its R configuration since it is not involved in the reaction.

Step 4: Analyze the stereochemistry of the starting material for part (b). The compound (3R, 4S)-3-bromo-4-methylhexane has the bromine atom on the 3rd carbon in the R configuration and a methyl group on the 4th carbon in the S configuration. When CH3O- attacks the 3rd carbon, the configuration at this carbon will invert to S due to the SN2 mechanism.

Step 5: Draw the product for part (b). After the substitution, the bromine is replaced by the methoxy group (-OCH3), and the stereochemistry at the 3rd carbon is inverted to S. The 4th carbon retains its S configuration since it is not involved in the reaction. If stereoisomers are possible, ensure to represent them clearly in the product structure.

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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 this context, the nucleophile is CH3O-, which attacks the carbon atom bonded to the bromine in the bromoalkane. Understanding the mechanism (either SN1 or SN2) is crucial, as it influences the stereochemistry of the products formed.

Stereochemistry and Stereoisomers

Stereochemistry refers to the spatial arrangement of atoms in molecules and how this affects their chemical behavior. Stereoisomers are compounds that have the same molecular formula and connectivity but differ in the orientation of their atoms in space. In the given reactions, the stereochemistry of the starting materials will determine the types of stereoisomers produced, which may include enantiomers and diastereomers.

Chirality and Optical Activity

Chirality is a property of a molecule that makes it non-superimposable on its mirror image, often due to the presence of a chiral center, typically a carbon atom with four different substituents. The presence of chirality in the products of the reactions can lead to optical activity, where the compounds can rotate plane-polarized light. Identifying chiral centers in the products is essential for determining the stereoisomers formed in the reactions.

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