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

SN2 Reaction

Organic Chemistry

7. Substitution Reactions

SN2 Reaction

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6:19 minutes

Problem 45a,b

Textbook Question

Predict the products of the following S_N2 reactions.
(a)
(b)

Verified step by step guidance

Step 1: Understand the SN2 reaction mechanism. SN2 reactions involve a single-step nucleophilic substitution where the nucleophile attacks the electrophilic carbon and simultaneously displaces the leaving group. This reaction is favored by primary or secondary alkyl halides and strong nucleophiles.

Step 2: Analyze reaction (a). CH3CH2ONa is a strong nucleophile (ethoxide ion), and CH3CH2Cl is a primary alkyl halide. The ethoxide ion will attack the electrophilic carbon in CH3CH2Cl, displacing the chloride ion (Cl⁻) as the leaving group. The product will be an ether formed via nucleophilic substitution.

Step 3: Analyze reaction (b). The molecule CH2CH2Br attached to a benzene ring is a primary alkyl bromide. NaCN provides the cyanide ion (CN⁻), which is a strong nucleophile. The cyanide ion will attack the electrophilic carbon bonded to the bromine atom, displacing the bromide ion (Br⁻) as the leaving group. The product will be a nitrile group (-CN) attached to the benzyl group.

Step 4: Consider stereochemistry. SN2 reactions proceed with inversion of configuration at the electrophilic carbon. However, in these cases, the electrophilic carbons are not chiral, so stereochemistry is not a concern.

Step 5: Write the general products. For reaction (a), the product is CH3CH2OCH2CH3 (an ether). For reaction (b), the product is benzyl cyanide (C6H5CH2CH2CN). These products are formed via the SN2 mechanism.

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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 the formation of a product with inversion of configuration at the carbon center. Understanding this mechanism is crucial for predicting the products of reactions involving primary and secondary alkyl halides.

Nucleophiles and Electrophiles

Nucleophiles are species that donate an electron pair to form a chemical bond, while electrophiles are electron-deficient species that accept electron pairs. In SN2 reactions, the nucleophile attacks the electrophile, which is typically a carbon atom bonded to a leaving group. Identifying the nucleophile and electrophile in a reaction is essential for predicting the outcome and products of the reaction.

Leaving Groups

Leaving groups are atoms or groups that can depart from the parent molecule during a chemical reaction, allowing for the formation of new bonds. In SN2 reactions, good leaving groups are typically weak bases that can stabilize the negative charge after departure. Common leaving groups include halides and sulfonate esters. Recognizing the nature of the leaving group is vital for understanding the reactivity and product formation in nucleophilic substitution reactions.

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Master Drawing the SN2 Mechanism with a bite sized video explanation from Johnny

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Predict the products of the following SN2 reactions. (a) (b)

Key Concepts

S<sub>N</sub>2 Mechanism

Nucleophiles and Electrophiles

Leaving Groups

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Predict the products of the following S_N2 reactions.
(a)
(b)