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

2:57 minutes

Problem 22c

Textbook Question

Predict the product of the following hydrogenation reactions.
(c)

Verified step by step guidance

Identify the type of reaction: Hydrogenation is a reaction where hydrogen (H₂) or its isotope (D₂) is added across a double or triple bond in an alkene or alkyne, converting it into a saturated compound (alkane). This reaction typically requires a metal catalyst such as Pd, Pt, or Ni.

Analyze the starting material: Determine the structure of the compound undergoing hydrogenation. Look for the presence of double or triple bonds, as these are the sites where hydrogen (or deuterium) will add.

Determine the stereochemistry: If the starting material is an alkene, the addition of hydrogen (or deuterium) occurs in a syn fashion, meaning both hydrogen atoms add to the same side of the double bond. This is due to the surface interaction with the metal catalyst.

Predict the product: Replace the double or triple bond in the starting material with single bonds, and add the appropriate number of hydrogen (H) or deuterium (D) atoms to the carbons that were part of the unsaturated bond. Ensure the product is fully saturated.

Verify the isotopic labeling: If D₂ is used instead of H₂, ensure that deuterium atoms (D) are added to the product instead of hydrogen atoms. This will result in a product where the added atoms are isotopically labeled with D.

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.

Hydrogenation

Hydrogenation is a chemical reaction that involves the addition of hydrogen (H2) to an unsaturated compound, typically an alkene or alkyne, converting it into a saturated compound. This process is commonly facilitated by catalysts such as palladium, platinum, or nickel. Understanding hydrogenation is crucial for predicting the products of reactions where unsaturated hydrocarbons are transformed into saturated ones.

Isotopes

Isotopes are variants of a particular chemical element that have the same number of protons but different numbers of neutrons, resulting in different atomic masses. In the context of hydrogenation, deuterium (D) is an isotope of hydrogen (H) that can participate in reactions similarly to hydrogen. Recognizing the role of isotopes is essential for predicting reaction outcomes when they are involved.

Reaction Mechanism

A reaction mechanism is a step-by-step description of the process by which reactants are converted into products in a chemical reaction. It outlines the sequence of elementary steps, including bond formation and breaking. Understanding the mechanism of hydrogenation reactions helps in predicting the specific products formed, especially when isotopes like deuterium are involved, as they may influence the reaction pathway.

Watch next

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

Start learning

Related Videos

Related Practice

Textbook Question

Predict the product of the following hydrogenation reactions run with a poisoned catalyst.

(b)

Textbook Question

Predict the product of the following hydrogenation reactions run with a poisoned catalyst.

(c)

Textbook Question

Hydrogenation of which alkynes would produce the following cis-alkenes?

(c)

Textbook Question

Predict the product of the following hydrogenation reactions.

(a)

Textbook Question

The following deprotonation step occurs during the trans reduction of an alkyne. Calculate K_eq for this reaction.

Textbook Question

Sodium amide, the base we use to deprotonate terminal alkynes, is synthesized by reducing ammonia via a mechanism similar to the reduction of alkynes in Figure 10.21. Suggest a mechanism for this reaction.

Textbook Question

Reduction of an alkyne using the Lindlar catalyst, a reaction presented in Section 10.6.2, produces only the cis-alkene. Why?

Textbook Question

Identify the product when each of the following reactions is performed on the triglyceride of linoleic acid (linoleate).

(a) H₂ , Pd

Show more practices