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

Making Ethers - Acid-Catalyzed Alkoxylation

Organic Chemistry

12. Alcohols, Ethers, Epoxides and Thiols

Making Ethers - Acid-Catalyzed Alkoxylation

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Problem 70(8)

Textbook Question

a. Draw the product or products that will be obtained from the reaction of cis-2-butene and trans-2-butene with each of the following reagents. If a product can exist as stereoisomers, show which stereoisomers are formed.
8. CH₃OH + H₂SO₄
b. With which reagents do the two alkenes react to form different products?

Verified step by step guidance

Step 1: Understand the reaction conditions. The reaction involves the addition of methanol (CH₃OH) in the presence of sulfuric acid (H₂SO₄). This is an acid-catalyzed electrophilic addition reaction, where the alkene reacts with the proton (H⁺) from H₂SO₄ to form a carbocation intermediate, followed by nucleophilic attack by methanol.

Step 2: Analyze the structure of the starting materials. Cis-2-butene and trans-2-butene are geometric isomers of 2-butene. Both have the same molecular formula (C₄H₈) but differ in the spatial arrangement of substituents around the double bond. Cis-2-butene has both methyl groups on the same side of the double bond, while trans-2-butene has them on opposite sides.

Step 3: Predict the carbocation intermediate. When the double bond reacts with H⁺, the proton adds to one of the carbons in the double bond, forming a carbocation on the other carbon. Due to Markovnikov's rule, the proton will add to the carbon with more hydrogens, resulting in the more stable carbocation intermediate.

Step 4: Determine the product(s). Methanol (CH₃OH) acts as a nucleophile and attacks the carbocation, forming an ether product. For both cis-2-butene and trans-2-butene, the product will be 2-methoxybutane. However, the stereochemistry of the starting material may influence the stereochemistry of the product. Since the reaction proceeds through a planar carbocation intermediate, the product will not retain the stereochemistry of the starting material.

Step 5: Address part (b) of the question. Both cis-2-butene and trans-2-butene will form the same product (2-methoxybutane) with CH₃OH and H₂SO₄. To form different products, the reagents must be stereospecific or involve a mechanism that retains stereochemistry, such as a syn-addition or anti-addition reaction. Examples of such reagents include bromine (Br₂) or osmium tetroxide (OsO₄).

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Key Concepts

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

Alkene Reactivity

Alkenes are unsaturated hydrocarbons characterized by at least one carbon-carbon double bond. Their reactivity is primarily due to this double bond, which can undergo various addition reactions. Understanding how alkenes react with different reagents, such as acids or alcohols, is crucial for predicting the products formed in these reactions.

Stereochemistry

Stereochemistry refers to the study of the spatial arrangement of atoms in molecules and how this affects their chemical behavior. In the context of alkenes, the configuration around the double bond can lead to different stereoisomers, such as cis and trans forms. Recognizing how reagents can influence stereochemical outcomes is essential for accurately depicting the products of reactions involving alkenes.

Electrophilic Addition

Electrophilic addition is a fundamental reaction mechanism for alkenes, where an electrophile reacts with the electron-rich double bond. In the presence of reagents like sulfuric acid and methanol, the double bond opens up, allowing for the formation of new bonds. This mechanism is key to understanding how different reagents can lead to distinct products, especially when considering the stereochemical implications of the reaction.

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