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

Previous problemNext problem

4:39 minutes

Problem 9c,d

Textbook Question

Which alkyl halide is more reactive in an S_N2 reaction with a given nucleophile?
c.
d.

Verified step by step guidance

Step 1: Understand the SN2 reaction mechanism. SN2 reactions are bimolecular nucleophilic substitution reactions where the nucleophile attacks the electrophilic carbon and displaces the leaving group in a single step. The reaction rate depends on steric hindrance and the quality of the leaving group.

Step 2: Analyze the leaving group. In part (a), the leaving group is iodine (I), which is a better leaving group than chlorine (Cl) due to its larger size and weaker bond to carbon. This makes the alkyl halide with iodine more reactive in SN2 reactions.

Step 3: Consider steric hindrance. In part (a), the alkyl halide with iodine on the secondary carbon is less sterically hindered compared to the alkyl halide with iodine on the tertiary carbon. SN2 reactions favor less sterically hindered substrates, so the secondary alkyl halide is more reactive.

Step 4: Examine the structure in part (b). The first structure has a benzyl chloride, where the leaving group is attached to a benzylic carbon. Benzyl carbons are less sterically hindered and stabilize the transition state due to resonance. The second structure has a chlorine attached to a primary alkyl chain, which is also favorable for SN2 but lacks resonance stabilization.

Step 5: Compare the reactivity in part (b). Benzyl chloride is more reactive in SN2 reactions compared to the primary alkyl chloride because the benzylic position provides resonance stabilization to the transition state, enhancing the reaction rate.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above

Video duration:

Play a video:

Was this helpful?

Key Concepts

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

SN2 Mechanism

The SN2 (substitution nucleophilic bimolecular) mechanism involves a single concerted step where a nucleophile attacks an electrophile, resulting in the displacement of a leaving group. This reaction is characterized by a backside attack, leading to inversion of configuration at the carbon center. The rate of the reaction depends on the concentration of both the nucleophile and the substrate.

Steric Hindrance

Steric hindrance refers to the crowding around a reactive site that can impede the approach of a nucleophile. In SN2 reactions, primary alkyl halides are more reactive than secondary or tertiary ones due to less steric hindrance. The presence of bulky groups near the reactive carbon can significantly slow down or prevent the reaction.

Leaving Group Ability

The ability of a leaving group to depart from the substrate is crucial in determining the reactivity of alkyl halides in SN2 reactions. Good leaving groups, such as iodide (I-) and bromide (Br-), stabilize the negative charge after leaving, facilitating the reaction. Conversely, poor leaving groups, like chloride (Cl-), hinder the reaction rate, making the substrate less reactive.

Watch next

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

Start learning

Related Videos

Related Practice

Textbook Question

Predict the products of the following S_N2 reactions.

(a)

(b)

Textbook Question

Predict the compound in each pair that will undergo the S_N2 reaction faster.

(a)

(b)

Textbook Question

Draw the substitution product formed by each of the following S_N2 reactions:

a. trans-1-iodo-4-ethylcyclohexane and methoxide ion

b. cis-1-chloro-3-methylcyclobutane and ethoxide ion

Textbook Question

Draw the products obtained from the S_N2 reaction of:

c. (S)-3-chlorohexane and hydroxide ion.

d. 3-iodopentane and hydroxide ion.

Textbook Question

Rank the following alkyl bromides from most reactive to least reactive in an S_N2 reaction:

1-bromo-2-methylbutane, 1-bromo-3-methylbutane, 2-bromo-2-methylbutane, and 1-bromopentane.

Textbook Question

Which alkyl halide is more reactive in an S_N2 reaction with a given nucleophile?

Textbook Question

Does increasing the energy barrier for an S_N2 reaction increase or decrease the magnitude of the rate constant for the reaction?

Textbook Question

The rate of the reaction of methyl iodide with quinuclidine was measured in nitrobenzene, and then the rate of the reaction of methyl iodide with triethylamine was measured in the same solvent. The concentration of the reagents was the same in both experiments.

a.Which reaction had the larger rate constant?

Show more practices

Download the Mobile app

Privacy

Do not sell my personal information

Accessibility

Patent notice

Sitemap

Which alkyl halide is more reactive in an SN2 reaction with a given nucleophile? c. d.

Key Concepts

SN2 Mechanism

Steric Hindrance

Leaving Group Ability

Watch next

Which alkyl halide is more reactive in an S_N2 reaction with a given nucleophile?
c.
d.