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

9. Alkenes and Alkynes

Hydrogenation of Alkynes

Organic Chemistry

9. Alkenes and Alkynes

Hydrogenation of Alkynes

Previous problemNext problem

4:18 minutes

Problem 34f

Textbook Question

Show how you would accomplish the following synthetic transformations. Show all intermediates.
f. cyclodecyne → cis-cyclodecene

Verified step by step guidance

Step 1: Analyze the transformation. The starting material is cyclodecyne, which contains a triple bond, and the target product is cis-cyclodecene, which contains a double bond in the cis configuration. This indicates that the reaction involves the reduction of the triple bond to a double bond while maintaining the cis geometry.

Step 2: Select an appropriate reagent for the reduction. To selectively reduce an alkyne to a cis-alkene, use a Lindlar catalyst. The Lindlar catalyst is a palladium catalyst poisoned with lead or quinoline, which prevents further reduction to an alkane and ensures the formation of a cis-alkene.

Step 3: Write the reaction mechanism. The Lindlar catalyst facilitates the addition of hydrogen (H₂) to the triple bond in a syn fashion, meaning both hydrogen atoms are added to the same side of the molecule. This syn addition results in the cis configuration of the double bond.

Step 4: Identify the intermediate. During the reaction, the triple bond is partially reduced to form a cis-alkene. No other intermediates are formed in this specific reaction pathway.

Step 5: Confirm the stereochemistry. The use of the Lindlar catalyst ensures that the double bond in the product is in the cis configuration, as opposed to the trans configuration, which would require a different reagent such as sodium in liquid ammonia.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above

Video duration:

Play a video:

Was this helpful?

Key Concepts

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

Cyclodecyne Structure

Cyclodecyne is a cyclic alkyne with a ten-membered carbon ring containing a triple bond. Understanding its structure is crucial for planning synthetic transformations, as the presence of the triple bond influences reactivity and the types of reactions that can be employed to convert it into other compounds.

Hydrogenation Reactions

Hydrogenation is a chemical reaction that involves the addition of hydrogen (H2) to unsaturated hydrocarbons, such as alkynes and alkenes. This process is essential for converting cyclodecyne into cis-cyclodecene, as it reduces the triple bond to a double bond while maintaining the stereochemistry required for the cis isomer.

Stereochemistry of Alkenes

Stereochemistry refers to the spatial arrangement of atoms in molecules and is particularly important in alkenes, where the orientation of substituents around the double bond can lead to different isomers. For the synthesis of cis-cyclodecene, it is vital to control the stereochemistry during the hydrogenation process to ensure the correct geometric isomer is formed.

Watch next

Master The definition of hydrogenation. with a bite sized video explanation from Johnny

Start learning