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

21. Aldehydes and Ketones: Nucleophilic Addition

Wittig Reaction

Organic Chemistry

21. Aldehydes and Ketones: Nucleophilic Addition

Wittig Reaction

Previous problemNext problem

4:37 minutes

Problem 26a

Textbook Question

Suggest the appropriate carbonyl and Wittig reagent to make the following alkenes.
a. (E)-7-methylnon-4-en-3-one

Verified step by step guidance

Step 1: Understand the Wittig reaction, which involves the reaction of a phosphonium ylide with a carbonyl compound to form an alkene. The ylide is typically formed from a triphenylphosphine and an alkyl halide.

Step 2: Identify the target alkene structure, (E)-7-methylnon-4-en-3-one. Note the position of the double bond and the stereochemistry (E configuration).

Step 3: Determine the carbonyl compound needed. The Wittig reaction forms the double bond at the site of the carbonyl group. For (E)-7-methylnon-4-en-3-one, the carbonyl group should be at the 3-position, suggesting the use of 3-oxononanal as the carbonyl compound.

Step 4: Identify the Wittig reagent. The Wittig reagent should provide the remaining carbon chain that forms the alkene. For (E)-7-methylnon-4-en-3-one, the Wittig reagent should be a phosphonium ylide derived from 4-methylbutyltriphenylphosphonium bromide.

Step 5: Consider the stereochemistry. The (E) configuration indicates that the Wittig reaction should be controlled to favor the trans product. This can be influenced by the choice of base and reaction conditions.

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.

Wittig Reaction

The Wittig reaction is a chemical reaction used to convert carbonyl compounds, such as aldehydes and ketones, into alkenes. This transformation involves the reaction of a phosphonium ylide with a carbonyl compound, resulting in the formation of a new carbon-carbon double bond. Understanding the mechanism and the stereochemistry of the Wittig reaction is crucial for predicting the structure of the resulting alkene.

Carbonyl Compounds

Carbonyl compounds are organic molecules that contain a carbon-oxygen double bond. They are key intermediates in many organic reactions, including the Wittig reaction. In the context of synthesizing alkenes, selecting the appropriate carbonyl compound is essential, as it determines the position and configuration of the double bond in the final alkene product.

Stereochemistry of Alkenes

Stereochemistry refers to the spatial arrangement of atoms in molecules and its impact on the physical and chemical properties of compounds. In alkenes, stereochemistry is particularly important because it affects the E/Z configuration of the double bond. For the synthesis of (E)-7-methylnon-4-en-3-one, understanding how to control and predict the stereochemistry during the Wittig reaction is crucial for obtaining the desired (E)-isomer.

Watch next

Master Box-Out Method and Full-Mechanism with a bite sized video explanation from Johnny

Start learning

Related Videos

Related Practice

Textbook Question

Like other strong nucleophiles, triphenylphosphine attacks and opens epoxides. The initial product (a betaine) quickly cyclizes to an oxaphosphetane that collapses to an alkene and triphenylphosphine oxide.

(b) Show how this sequence might be used to convert cis-cyclooctene to trans-cyclooctene.

Textbook Question

Show how you would accomplish the following syntheses efficiently and in good yield. You may use any necessary reagents.

(e)

Textbook Question

Show how you would accomplish the following synthetic conversions efficiently and in good yield. You may use any necessary additional reagents and solvents.

(h)

Textbook Question

What two sets of reagents (each consisting of a carbonyl compound and phosphonium ylide) can be used for the synthesis of the following alkene?

Multiple Choice

Determine the carbonyl and ylide that formed the following product.

Multiple Choice

Predict the major, organic product for the following reaction.

Textbook Question

Trimethylphosphine is a stronger nucleophile than triphenylphosphine, but it is rarely used to make ylides. Why is trimethylphosphine unsuitable for making most phosphorus ylides?

Textbook Question

Propose mechanisms for the following reactions.

(c)

Show more practices