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

16. Conjugated Systems

Photochemical Electrocyclic Reactions

Organic Chemistry

16. Conjugated Systems

Photochemical Electrocyclic Reactions

Previous problemNext problem

Problem 27b

Textbook Question

Predict the product of the following [2 + 2] cycloadditions.
(b)

Verified step by step guidance

Identify the reactants: The given structure is a 1,5-hexadiene, which consists of two alkenes separated by a methylene group.

Understand the reaction type: A [2 + 2] cycloaddition involves the formation of a four-membered ring from two alkenes. Under photochemical conditions (hv), this reaction is allowed due to the involvement of excited states.

Consider the possible interactions: The two alkenes in 1,5-hexadiene can interact in two different ways to form cyclobutane rings. These interactions can occur between the terminal alkenes or between one terminal and the internal alkene.

Predict the first product: When the two terminal alkenes react, a cyclobutane ring is formed, resulting in a bicyclic structure with a bridgehead carbon.

Predict the second product: When one terminal alkene reacts with the internal alkene, a different cyclobutane ring is formed, leading to a different bicyclic structure. Both products are possible due to the symmetry and flexibility of the molecule.

Verified video answer for a similar problem:

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

Play a video:

Was this helpful?

Key Concepts

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

[2 + 2] Cycloaddition

[2 + 2] Cycloaddition is a chemical reaction where two alkenes or alkynes form a four-membered ring. This reaction is typically photochemically induced, as thermal conditions often lead to different outcomes due to symmetry restrictions. The reaction involves the overlap of two π-bonds, resulting in the formation of two new σ-bonds, creating a cyclobutane ring.

Photochemical Reactions

Photochemical reactions are chemical reactions initiated by the absorption of light, often ultraviolet or visible. In organic chemistry, light can provide the energy needed to overcome activation barriers, allowing reactions that are otherwise symmetry-forbidden under thermal conditions. The symbol 'hv' denotes the involvement of light, indicating that the reaction proceeds via an excited state.

Stereochemistry in Cycloadditions

Stereochemistry plays a crucial role in cycloaddition reactions, influencing the spatial arrangement of atoms in the resulting product. In [2 + 2] cycloadditions, the orientation of substituents on the reacting alkenes can lead to different stereoisomers. The reaction can yield both cis and trans isomers, depending on the relative orientation of the substituents in the starting materials and the reaction conditions.

Watch next

Master MO Theory of Photochemical Electrocyclics with a bite sized video explanation from Johnny

Start learning

Related Videos

Related Practice

Textbook Question

Draw the product formed when each of the following compounds undergoes an electrocyclic reaction

b. under photochemical conditions.

Textbook Question

Chorismate mutase is an enzyme that promotes a pericyclic reaction by forcing the substrate to assume the conformation needed for the reaction. The product of the pericyclic reaction is prephenate that is subsequently converted into the amino acids phenylalanine and tyrosine. What kind of a pericyclic reaction does chorismate mutase catalyze?

Textbook Question

Predict the product of the following electrocyclic reactions.

(c)

Textbook Question

Draw the product of each of the following reactions:

Textbook Question

Predict the product of the following electrocyclic reactions.

(b)

Textbook Question

c. Under photochemical conditions, will ring closure be conrotatory or disrotatory?

d. Will the product have the cis or the trans configuration?

Textbook Question

Explain why the hydrogen and the methyl substituent are trans to one another after photochemical ring closure of provitamin D₃ to form 7-dehydrocholesterol.

Textbook Question

Draw the product of each of the following reactions:

Show more practices

Download the Mobile app

Privacy

Do not sell my personal information

Accessibility

Patent notice

Sitemap

Predict the product of the following [2 + 2] cycloadditions.(b)

Key Concepts

[2 + 2] Cycloaddition

Photochemical Reactions

Stereochemistry in Cycloadditions

Watch next

Predict the product of the following [2 + 2] cycloadditions.
(b)