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

10. Addition Reactions

Alkyne Oxidative Cleavage

Organic Chemistry

10. Addition Reactions

Alkyne Oxidative Cleavage

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5:40 minutes

Problem 23a

Textbook Question

Predict the product(s) you would expect from treatment of each compound with (1) dilute, neutral KMnO₄ and (2) warm basic KMnO₄, then dilute acid.
(a) hex-1-yne

Verified step by step guidance

Step 1: Understand the reactivity of KMnO4 with alkynes. Neutral, dilute KMnO4 typically performs mild oxidation, while warm, basic KMnO4 followed by acid treatment leads to oxidative cleavage of the triple bond.

Step 2: For reaction with dilute, neutral KMnO4, recognize that hex-1-yne will undergo mild oxidation. The triple bond will be converted into a diol (a compound with two hydroxyl groups) at the site of the triple bond.

Step 3: For reaction with warm, basic KMnO4 followed by acid treatment, understand that the triple bond in hex-1-yne will be cleaved completely. Each carbon of the triple bond will be oxidized to form carboxylic acids.

Step 4: Identify the structure of hex-1-yne. It is a six-carbon alkyne with the triple bond located between the first and second carbons. For oxidative cleavage, the products will depend on the position of the triple bond.

Step 5: Predict the products. For dilute KMnO4, the product will be a diol at the triple bond site. For warm, basic KMnO4 followed by acid, the triple bond will cleave, yielding acetic acid (CH₃COOH) and pentanoic acid (C₄H₉COOH).

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Key Concepts

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

Alkyne Reactivity

Alkynes, characterized by a carbon-carbon triple bond, undergo various reactions due to their high reactivity. They can participate in addition reactions, where reagents add across the triple bond, and oxidation reactions, which can lead to the formation of carbonyl compounds or carboxylic acids depending on the conditions.

Oxidation with KMnO4

Potassium permanganate (KMnO4) is a strong oxidizing agent used in organic chemistry. In dilute, neutral conditions, it typically oxidizes alkynes to form cis-diol products, while in warm basic conditions followed by acid treatment, it can cleave the triple bond, resulting in carboxylic acids or ketones, depending on the structure of the alkyne.

Mechanism of Oxidation

The mechanism of oxidation with KMnO4 involves the formation of a cyclic manganate ester intermediate, which subsequently leads to the addition of hydroxyl groups across the double bond. Understanding this mechanism is crucial for predicting the products of the reaction, as it dictates the stereochemistry and the nature of the final products formed from the alkyne.

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Related Practice

Textbook Question

Predict the product(s) you would expect from treatment of each compound with (1) dilute, neutral KMnO₄ and (2) warm basic KMnO₄, then dilute acid.

(d) 2-methylhex-3-yne

Textbook Question

Predict the product(s) you would expect from treatment of each compound with (1) dilute, neutral KMnO₄ and (2) warm basic KMnO₄, then dilute acid.

(e) cyclodecyne

Textbook Question

Deduce the structure of each compound from the information given. All unknowns in this problem have molecular formula C₈H₁₂.

(a) Upon catalytic hydrogenation, unknown W gives cyclooctane. Ozonolysis of W, followed by reduction with dimethyl sulfide, gives octanedioic acid, HOOC–(CH₂)₆–COOH. Draw the structure of W.

Textbook Question

Predict the product(s) you would expect from treatment of each compound with (1) dilute, neutral KMnO4 and (2) warm basic KMnO4, then dilute acid.

(b) hex-2-yne

Textbook Question

Predict the product(s) you would expect from treatment of each compound with (1) dilute, neutral KMnO₄ and (2) warm basic KMnO₄, then dilute acid.

Textbook Question

Show how you would synthesize the following carboxylic acids, using the indicated starting materials.

(a) oct-4-yne → butanoic acid

(b) trans-cyclodecene → decanedioic acid

Textbook Question

When treated with hydrogen and a platinum catalyst, an unknown compound X absorbs 5 equivalents of hydrogen to give n-butylcyclohexane. Treatment of X with an excess of ozone, followed by dimethyl sulfide and water, gives the following products:

Propose a structure for the unknown compound X. Is there any uncertainty in your structure?

Textbook Question

Predict the products of reaction of pent-1-yne with the following reagents.

g. cold, dilute KMnO₄

h. warm, concd. KMnO₄, NaOH

i. Na, liquid ammonia

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