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

Cumulative Substitution/Elimination

Organic Chemistry

8. Elimination Reactions

Cumulative Substitution/Elimination

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Problem 56d

Textbook Question

Predict the product(s) of the following substitution or elimination reactions, paying close attention to the stereochemical outcome of the reactions.
(d)

Verified step by step guidance

Identify the type of reaction: The reagent triphenylphosphine (Ph₃P) in tetrahydrofuran (THF) is commonly used in nucleophilic substitution reactions, particularly in the formation of phosphonium salts.

Analyze the substrate: The given substrate is a secondary alkyl bromide. Secondary alkyl halides can undergo nucleophilic substitution reactions, and the bromine atom is a good leaving group.

Determine the mechanism: Triphenylphosphine (Ph₃P) acts as a nucleophile and attacks the carbon atom bonded to the bromine, displacing the bromide ion (Br⁻) in an SN2 mechanism. This results in the formation of a phosphonium salt.

Consider stereochemistry: Since the reaction proceeds via an SN2 mechanism, the configuration at the carbon center will invert. If the starting material has a chiral center, the product will have the opposite stereochemistry.

Write the product: The product will be a phosphonium salt where the triphenylphosphine group (Ph₃P⁺) is bonded to the carbon that originally held the bromine atom, with inversion of configuration if applicable.

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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. These reactions can occur via two main mechanisms: SN1, which is a two-step process involving carbocation formation, and SN2, which is a one-step process where the nucleophile attacks the substrate simultaneously as the leaving group departs. Understanding the mechanism is crucial for predicting the products and their stereochemistry.

Elimination Reactions

Elimination reactions involve the removal of a leaving group and a hydrogen atom from adjacent carbon atoms, resulting in the formation of a double bond. The two primary types are E1, which proceeds through a carbocation intermediate, and E2, which is a concerted mechanism. The choice between substitution and elimination often depends on the structure of the substrate and the reaction conditions, influencing the stereochemical outcome.

Stereochemistry

Stereochemistry refers to the spatial arrangement of atoms in molecules and how this affects their chemical behavior. In substitution and elimination reactions, the stereochemical outcome can lead to different isomers, such as cis/trans or R/S configurations. Understanding stereochemistry is essential for predicting the specific products formed, especially in reactions involving chiral centers or when stereoselectivity is a factor.

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Related Practice

Textbook Question

Predict the product(s) that would result when molecules (a)–(p) are allowed to react under the following conditions: (ii) PBr₃ If no reaction occurs, write 'no reaction.'

(c)

Textbook Question

Predict the product(s) that would result when molecules (a)–(p) are allowed to react under the following conditions: (vii) HCl; (viii) HBr; If no reaction occurs, write 'no reaction.'

(c)

Textbook Question

Predict the product(s) that would result when molecules (a)–(p) are allowed to react under the following conditions: (v) 1. TsCl, Et₃N 2. NaOt-Bu (vi) H₂SO₄ If no reaction occurs, write 'no reaction.'

(f)

Textbook Question

Predict the product(s) of the following substitution or elimination reactions, paying close attention to the stereochemical outcome of the reactions.

(a)

Textbook Question

Predict the product(s) of the following substitution or elimination reactions, paying close attention to the stereochemical outcome of the reactions.

(e)

Textbook Question

Given the reactants shown, what type of elimination would you expect to occur?

(b)

Textbook Question

Show a mechanism for the following elimination reactions. Label the mechanism as E1 or E2.

(c)

Textbook Question

Would you expect the following bases to favor E1 or E2 elimination?

(d) H₂O

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Predict the product(s) of the following substitution or elimination reactions, paying close attention to the stereochemical outcome of the reactions.(d)

Key Concepts

Nucleophilic Substitution Reactions

Elimination Reactions

Stereochemistry

Watch next

Predict the product(s) of the following substitution or elimination reactions, paying close attention to the stereochemical outcome of the reactions.
(d)