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

8. Elimination Reactions

SN1 SN2 E1 E2 Chart (Big Daddy Flowchart)

Organic Chemistry

8. Elimination Reactions

SN1 SN2 E1 E2 Chart (Big Daddy Flowchart)

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3:17 minutes

Problem 115c

Textbook Question

Draw the products of each of the following S_N2/E2 reactions. If the products can exist as stereoisomers, show which stereoisomers are formed.
c. (3S,4R)-3-bromo-4-methylhexane + CH₃O⁻

Verified step by step guidance

Analyze the reaction type: The problem specifies SN2/E2 reactions. SN2 (bimolecular nucleophilic substitution) and E2 (bimolecular elimination) are competing mechanisms. The choice depends on the substrate, nucleophile/base, and reaction conditions. Here, CH3O− is a strong nucleophile and a strong base, so both SN2 and E2 are possible.

Examine the substrate: The substrate is (3S,4R)-3-bromo-4-methylhexane. The bromine atom is attached to the 3rd carbon, making it a good leaving group. The stereochemistry at the 3rd carbon is S, and the 4th carbon has an R configuration with a methyl group attached.

Consider the SN2 pathway: In an SN2 reaction, the nucleophile (CH3O−) attacks the carbon bonded to the leaving group (C-3) from the opposite side, leading to an inversion of configuration at C-3. This results in a product with the 3rd carbon having an R configuration. The stereochemistry at C-4 remains unchanged (R).

Consider the E2 pathway: In an E2 reaction, the base (CH3O−) abstracts a β-hydrogen (a hydrogen on a carbon adjacent to the carbon bearing the leaving group). Here, β-hydrogens are available on both C-2 and C-4. Elimination of H from C-2 forms a double bond between C-2 and C-3, while elimination of H from C-4 forms a double bond between C-3 and C-4. The resulting alkenes can have E/Z stereoisomers depending on the spatial arrangement of substituents around the double bond.

Draw the products: For the SN2 pathway, draw the product with inversion of configuration at C-3. For the E2 pathway, draw the two possible alkenes (one with a double bond between C-2 and C-3, and the other with a double bond between C-3 and C-4), showing both E and Z stereoisomers for each alkene. Ensure the stereochemistry at C-4 remains consistent with the original R configuration.

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Key Concepts

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

SN2 Mechanism

The SN2 mechanism is a type of nucleophilic substitution reaction where a nucleophile attacks an electrophile, resulting in the simultaneous displacement of a leaving group. This reaction occurs in a single concerted step, leading to inversion of configuration at the carbon center. It is favored by primary and some secondary substrates, particularly in polar aprotic solvents.

E2 Mechanism

The E2 mechanism is a bimolecular elimination reaction where a base abstracts a proton from a β-carbon while a leaving group departs from the α-carbon, resulting in the formation of a double bond. This reaction requires a strong base and typically occurs in a single concerted step. The stereochemistry of the reaction is important, as it often leads to the formation of specific geometric isomers.

Stereoisomerism

Stereoisomerism refers to the phenomenon where compounds have the same molecular formula and connectivity but differ in the spatial arrangement of atoms. In the context of SN2 and E2 reactions, stereoisomers can arise due to the configuration of chiral centers or the geometry of double bonds. Understanding stereoisomerism is crucial for predicting the products of these reactions, as different stereoisomers can exhibit distinct physical and chemical properties.

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Related Practice

Textbook Question

For each of the following reactions, draw the major elimination product; if the product can exist as stereoisomers, indicate which stereoisomer is obtained in greater yield.

a. (R)-2-bromohexane + high concentration of CH₃O⁻

b. (R)-3-bromo-3-methylhexane + CH₃OH

Textbook Question

What are the products of the following reactions?

Textbook Question

Explain how each of the following changes affect the rate of the reaction of 1-bromobutane with ethoxide ion in DMF.

c. The alkyl halide is changed to 1-chlorobutane.

d. The alkyl halide is changed to 2-bromobutane.

Textbook Question

What are the products of the following reactions?

Textbook Question

What products (including stereoisomers, if applicable) are formed from the reaction of 3-bromo-3-methylpentane:

b. with H₂O?

Textbook Question

Which of these reactions are likely to produce both elimination and substitution products?

a. 2-bromopentane + NaOCH₃

b. 3-bromo-3-methylpentane + NaOMe. (Me = methyl, CH₃)

c. 2-bromo-3-ethylpentane + NaOH

Textbook Question

For each reaction, decide whether substitution or elimination (or both) is possible, and predict the products you expect. Label the major products.

c. chlorocyclohexane+NaOCH₃in CH₃OH

d. chlorocyclohexane + NaOC(CH₃)₃ in (CH₃)₃COH

Textbook Question

Silver-assisted solvolysis of bromomethylcyclopentane in methanol gives a complex product mixture of the following five compounds. Propose mechanisms to account for these products.

(a)

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Draw the products of each of the following SN2/E2 reactions. If the products can exist as stereoisomers, show which stereoisomers are formed.c. (3S,4R)-3-bromo-4-methylhexane + CH3O−

Key Concepts

S<sub>N</sub>2 Mechanism

E2 Mechanism

Stereoisomerism

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Draw the products of each of the following S_N2/E2 reactions. If the products can exist as stereoisomers, show which stereoisomers are formed.
c. (3S,4R)-3-bromo-4-methylhexane + CH₃O⁻