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

12. Alcohols, Ethers, Epoxides and Thiols

Leaving Group Conversions - Using HX

Organic Chemistry

12. Alcohols, Ethers, Epoxides and Thiols

Leaving Group Conversions - Using HX

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6:34 minutes

Problem 16

Textbook Question

Explain the products observed in the following reaction of an alcohol with the Lucas reagent.

Verified step by step guidance

Step 1: Recognize the reaction type. The reaction involves an alcohol reacting with Lucas reagent (HCl/ZnCl₂). Lucas reagent is used to test the reactivity of alcohols and convert them into alkyl chlorides via an SN1 or SN2 mechanism depending on the alcohol type.

Step 2: Analyze the structure of the alcohol. The alcohol in the reaction is a secondary alcohol, as the hydroxyl group (-OH) is attached to a carbon atom that is bonded to two other carbon atoms. Secondary alcohols typically undergo substitution reactions via the SN1 mechanism in the presence of Lucas reagent.

Step 3: Understand the mechanism. In the SN1 mechanism, the reaction proceeds through the formation of a carbocation intermediate. The hydroxyl group is protonated by HCl, forming water as a leaving group. This leads to the generation of a carbocation intermediate.

Step 4: Consider carbocation stability. The carbocation formed is stabilized by hyperconjugation and inductive effects from the surrounding alkyl groups. This stability allows the reaction to proceed efficiently.

Step 5: Formation of products. The chloride ion (Cl⁻) from HCl attacks the carbocation, leading to the formation of two stereoisomeric alkyl chlorides due to the planar nature of the carbocation intermediate. These products are observed as the final result of the reaction.

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Key Concepts

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

Lucas Reagent

The Lucas reagent is a solution of hydrochloric acid (HCl) and zinc chloride (ZnCl2) used to convert alcohols into alkyl chlorides. It is particularly effective for distinguishing between primary, secondary, and tertiary alcohols based on their reactivity. Tertiary alcohols react rapidly, while primary alcohols react slowly or not at all, allowing for the identification of alcohol types.

Alcohol Reactivity

Alcohols can be classified as primary, secondary, or tertiary based on the number of carbon atoms attached to the carbon bearing the hydroxyl (-OH) group. This classification affects their reactivity with reagents like the Lucas reagent. Tertiary alcohols undergo rapid substitution reactions, while primary alcohols require stronger conditions to react, influencing the products formed in the reaction.

Substitution Reaction

A substitution reaction involves the replacement of one functional group in a molecule with another. In the context of the reaction with the Lucas reagent, the hydroxyl group of the alcohol is replaced by a chlorine atom, resulting in the formation of alkyl chlorides. This type of reaction is fundamental in organic chemistry, as it allows for the transformation of functional groups and the synthesis of various compounds.

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Textbook Question

Protonation converts the hydroxy group of an alcohol to a good leaving group. Suggest a mechanism for each reaction.

(a)

Textbook Question

What product would be formed if the four-membered ring alcohol in Problem 70 were heated with an equivalent amount of HBr rather than with a catalytic amount of H₂SO₄?

Textbook Question

Propose a mechanism for each of the following reactions:

Textbook Question

When 3-methyl-2-butanol is heated with concentrated HBr, a rearranged product is obtained. When 2-methyl-1-propanol reacts under the same conditions, a rearranged product is not obtained. Explain.

Textbook Question

Show how you would use a simple chemical test to distinguish between the following pairs of compounds. Tell what you would observe with each compound.

(d) allyl alcohol and propan-1-ol

(e) butan-2-one and tert-butyl alcohol

Textbook Question

Neopentyl alcohol, (CH₃)₃CCH₂OH, reacts with concentrated HBr to give 2-bromo-2-methylbutane, a rearranged product. Propose a mechanism for the formation of this product.

Textbook Question

The reaction of tert-butyl alcohol with concentrated HCl goes by the S_N1 mechanism. Write a mechanism for this reaction.

Textbook Question

Suggest a mechanism for the following reactions.

(b) Substitution :

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