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

E1 Reaction

Organic Chemistry

8. Elimination Reactions

E1 Reaction

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2:47 minutes

Problem 39b

Textbook Question

Which reacts faster in an E1 reaction?

Verified step by step guidance

Step 1: Understand the E1 reaction mechanism. E1 reactions are unimolecular elimination reactions where the rate-determining step involves the formation of a carbocation intermediate. The stability of the carbocation formed is a key factor in determining the reaction rate.

Step 2: Analyze the leaving groups in the given molecules. In the first molecule, the leaving group is iodine (I), and in the second molecule, the leaving group is bromine (Br). The ability of a leaving group to depart is influenced by its size and electronegativity.

Step 3: Compare the leaving group abilities of iodine and bromine. Iodine is a better leaving group than bromine because it is larger and can stabilize the negative charge better after leaving. This makes the molecule with iodine more likely to undergo the E1 reaction faster.

Step 4: Consider the carbocation stability. Both molecules form a secondary carbocation upon the departure of the leaving group. Since the carbocation environments are identical, the leaving group ability becomes the deciding factor.

Step 5: Conclude that the molecule with iodine as the leaving group reacts faster in an E1 reaction due to iodine's superior leaving group ability compared to bromine.

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Key Concepts

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

E1 Reaction Mechanism

The E1 reaction is a type of elimination reaction that occurs in two steps: first, the formation of a carbocation intermediate, followed by the loss of a proton to form a double bond. The rate of an E1 reaction depends primarily on the stability of the carbocation formed, as the first step is the rate-determining step. Thus, more stable carbocations, such as tertiary carbocations, will react faster.

Carbocation Stability

Carbocation stability is a crucial factor in determining the rate of E1 reactions. Carbocations are positively charged species that can be stabilized by hyperconjugation and inductive effects from adjacent alkyl groups. Tertiary carbocations are the most stable due to the presence of three alkyl groups, while primary carbocations are the least stable, influencing the speed of the reaction.

Solvent Effects on E1 Reactions

The choice of solvent can significantly impact the rate of E1 reactions. Polar protic solvents stabilize carbocations through solvation, which can enhance the reaction rate. In contrast, polar aprotic solvents may not stabilize the carbocation as effectively, leading to slower reaction rates. Understanding solvent effects is essential for predicting the reactivity of different substrates in E1 reactions.

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