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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5:11 minutes

Problem 23c

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.
(c) hex-3-yne

Verified step by step guidance

Step 1: Understand the reaction conditions. Neutral KMnO4 (dilute, neutral potassium permanganate) is a mild oxidizing agent that typically adds hydroxyl groups across double or triple bonds, resulting in diols. Warm, basic KMnO4 followed by acidification is a stronger oxidizing agent that cleaves double or triple bonds, producing carboxylic acids or ketones depending on the substituents attached to the carbons involved in the bond.

Step 2: Analyze the structure of hex-3-yne. Hex-3-yne is an alkyne with a triple bond between carbons 3 and 4 in a six-carbon chain. The structure can be written as CH3-CH2-C≡C-CH2-CH3.

Step 3: Predict the product with dilute, neutral KMnO4. Neutral KMnO4 will add hydroxyl groups across the triple bond, converting it into a diol. The triple bond will first be oxidized to a double bond, and then hydroxyl groups (-OH) will be added to each carbon of the former triple bond, resulting in a vicinal diol (a compound with two hydroxyl groups on adjacent carbons).

Step 4: Predict the product with warm, basic KMnO4 followed by acidification. Under these conditions, the triple bond in hex-3-yne will be cleaved completely. Each carbon of the triple bond will be oxidized to a carboxylic acid group (-COOH). Since the triple bond is symmetrically located in the middle of the chain, the products will be two molecules of propanoic acid (CH3-CH2-COOH).

Step 5: Summarize the results. For dilute, neutral KMnO4, the product is a vicinal diol. For warm, basic KMnO4 followed by acidification, the product is two molecules of propanoic acid. Ensure you understand the difference in reactivity between the mild and strong oxidizing conditions.

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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. In the presence of oxidizing agents like KMnO4, alkynes can be converted into carbonyl compounds or carboxylic acids, depending on the reaction conditions. Understanding the structure and reactivity of alkynes is crucial for predicting the products of their reactions.

Oxidation with KMnO4

Potassium permanganate (KMnO4) is a strong oxidizing agent used in organic chemistry to oxidize alkenes and alkynes. In dilute, neutral conditions, KMnO4 typically leads to syn-dihydroxylation, while warm basic KMnO4 can cleave the triple bond, resulting in the formation of carboxylic acids. The conditions of the reaction significantly influence the outcome, making it essential to consider them when predicting products.

Acidic Workup

An acidic workup, often involving dilute acid, is a common step following oxidation reactions to neutralize any remaining reagents and stabilize the products. In the case of KMnO4 oxidation, this step can help convert intermediate products into their more stable forms, such as converting alkoxide ions into alcohols or carboxylic acids. Understanding the role of the acidic workup is vital for accurately determining the final products of the reaction.

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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.

(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.

(a) hex-1-yne

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

Textbook Question

Oxidative cleavages can help to determine the positions of the triple bonds in alkynes.

(a) An unknown alkyne undergoes oxidative cleavage to give adipic acid and two equivalents of acetic acid. Propose a structure for the alkyne.

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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.(c) hex-3-yne

Key Concepts

Alkyne Reactivity

Oxidation with KMnO4

Acidic Workup

Watch next

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.
(c) hex-3-yne