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

Substitution Comparison

Organic Chemistry

7. Substitution Reactions

Substitution Comparison

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3:43 minutes

Problem 21a,b,c

Textbook Question

Which of the following reactions take place more rapidly when the concentration of the nucleophile is increased?

Verified step by step guidance

Step 1: Analyze the reaction mechanisms for each reaction. Reaction A involves a secondary alkyl bromide and CH3O− as the nucleophile. Reaction B involves a primary alkyl bromide and CH3S− as the nucleophile. Reaction C involves a tertiary alkyl bromide and CH3COO− as the nucleophile.

Step 2: Determine the type of substitution mechanism (SN1 or SN2) for each reaction. SN2 reactions are bimolecular and depend on the concentration of both the nucleophile and the substrate, while SN1 reactions are unimolecular and depend only on the substrate concentration.

Step 3: Reaction A likely proceeds via an SN2 mechanism because the secondary alkyl bromide is accessible to the nucleophile, and CH3O− is a strong nucleophile. SN2 reactions are faster when the nucleophile concentration is increased.

Step 4: Reaction B also likely proceeds via an SN2 mechanism because the primary alkyl bromide is highly accessible to the nucleophile, and CH3S− is a strong nucleophile. Increasing the nucleophile concentration will speed up the reaction.

Step 5: Reaction C likely proceeds via an SN1 mechanism because the tertiary alkyl bromide forms a stable carbocation intermediate. The rate of an SN1 reaction is independent of the nucleophile concentration, so increasing the nucleophile concentration will not affect the reaction rate.

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Key Concepts

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

Nucleophilicity

Nucleophilicity refers to the ability of a nucleophile to donate an electron pair to an electrophile during a chemical reaction. It is influenced by factors such as charge, electronegativity, and steric hindrance. A stronger nucleophile will react more readily with an electrophile, making the reaction faster as the concentration of the nucleophile increases.

Reaction Mechanism

The reaction mechanism describes the step-by-step process by which reactants are converted into products. Understanding whether a reaction proceeds via a single step or multiple steps is crucial, as it affects how changes in nucleophile concentration influence the reaction rate. For example, in a bimolecular nucleophilic substitution (SN2) reaction, increasing nucleophile concentration directly increases the reaction rate.

Rate Law

The rate law is an equation that relates the rate of a reaction to the concentration of its reactants. It is expressed in the form Rate = k [A]^m [B]^n, where k is the rate constant, and m and n are the orders of the reaction with respect to reactants A and B. For reactions where the nucleophile is a reactant, increasing its concentration will typically increase the reaction rate, as indicated by the rate law.

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Textbook Question

Suggest a reagent to carry out each of the following conversions to an alcohol.

(c)

Textbook Question

Predict the product(s) of the following reactions.

(f)

Textbook Question

Predict the product(s) of the following reactions.

(g)

Textbook Question

When trans-4-bromocyclohexanol is treated with base, an intramolecular substitution reaction occurs to give a cyclic ether. This product does not form when cis-4-bromocyclohexanol is reacted under the same conditions. Explain these observations.

Textbook Question

Starting with (R)-1-deuterio-1-propanol, how could you prepare

c. (R)-1-deuterio-1-methoxypropane?

Textbook Question

Even with an excess of cyanide, only one equivalent will react with the following dibromoalkane. To which carbon will the cyanide add? Predict the product and explain your choice.

Textbook Question

Suggest a mechanism for the following reactions.

(a) Substitution:

Textbook Question

Predict the product(s) that would result when molecules (a)–(p) are allowed to react under the following conditions: (i) SOCl₂ ; (ii) PBr₃ ; (iii) SOCl₂ , NEt₃ (iv) 1. TsCl, Et₃N 2. NaCN; (v) 1. TsCl, Et₃N 2. NaOt-Bu (vi) H₂SO₄ (vii) HCl; (viii) HBr; (ix) PCC; (x) H₂CrO₄ , H₂O (xi) HOCl, H₂O (xii) HIO₄ If no reaction occurs, write 'no reaction.'

(o)

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