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

3. Acids and Bases

Reaction Mechanism

Organic Chemistry

3. Acids and Bases

Reaction Mechanism

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4:34 minutes

Problem 69a

Textbook Question

Use curved arrows to show the flow of electrons that occurs in each step of the following mechanism

Verified step by step guidance

Step 1: Identify the electrophile and nucleophile in the reaction. In this case, HBr acts as the electrophile, with the hydrogen atom being electron-deficient, and the alkene acts as the nucleophile due to the π-electrons in the double bond.

Step 2: Use a curved arrow to show the flow of electrons from the π-bond of the alkene to the hydrogen atom of HBr. This forms a new bond between the hydrogen and one of the carbon atoms in the double bond, breaking the π-bond.

Step 3: As the π-electrons move to bond with hydrogen, the bond between hydrogen and bromine in HBr breaks. Use a curved arrow to show the flow of electrons from the H-Br bond to bromine, resulting in the formation of a bromide ion (Br⁻).

Step 4: The carbon atom that does not bond with hydrogen becomes a carbocation (positively charged). This carbocation is stabilized by the surrounding alkyl groups through hyperconjugation and inductive effects.

Step 5: Use a curved arrow to show the flow of electrons from the lone pair on the bromide ion (Br⁻) to the carbocation. This forms a new bond between the bromine atom and the positively charged carbon, completing the addition reaction.

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Key Concepts

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

Curved Arrows in Mechanisms

Curved arrows are used in organic chemistry to represent the movement of electrons during chemical reactions. The tail of the arrow indicates the electron source, while the head points to the electron destination. This notation helps visualize the flow of electrons, which is crucial for understanding reaction mechanisms, including nucleophilic attacks and electrophilic additions.

Acid-Base Reactions

Acid-base reactions involve the transfer of protons (H+) between reactants. In the context of the provided mechanism, a Brønsted acid donates a proton to a base, leading to the formation of a conjugate acid and a conjugate base. Understanding the roles of acids and bases is essential for predicting the outcome of reactions and the stability of intermediates.

Electrophiles and Nucleophiles

Electrophiles are electron-deficient species that seek electrons, while nucleophiles are electron-rich species that donate electrons. In the mechanism shown, the bromine molecule acts as an electrophile, and the alkene acts as a nucleophile. Recognizing these roles is vital for predicting how molecules will interact and react in organic reactions.

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Related Practice

Textbook Question

For each of the reactions in Problem 15, indicate which reactant is the nucleophile and which is the electrophile.

Textbook Question

Use curved arrows to show the movement of electrons in the following reaction steps

Textbook Question

We discuss the following reactions in subsequent chapters. Given the mechanisms shown, draw the mechanism of the reverse reaction.

(a)

Textbook Question

We discuss the following reactions in subsequent chapters. Given the mechanisms shown, draw the mechanism of the reverse reaction.

(b)

Textbook Question

Identify the electrophile and the nucleophile in each of the following reaction steps. Then draw curved arrows to illustrate the bond-making and bond-breaking processes.

Textbook Question

The following reaction steps are shown using conventional electron pushing. (b) Use the bouncing arrow formalism to illustrate the formation of only the product shown.

(c)

Textbook Question

Predict the product that results from the following 'pushed electrons.'

(a)

Textbook Question

Predict the product that results from the following 'pushed electrons.'

(c)

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