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

Conjugated Hydrohalogenation (1,2 vs 1,4 addition)

Organic Chemistry

16. Conjugated Systems

Conjugated Hydrohalogenation (1,2 vs 1,4 addition)

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6:01 minutes

Problem 25e

Textbook Question

Predict the products of the following reactions.
(e) buta-1,3-diene + bromine water

Verified step by step guidance

Identify the type of reaction: The reaction involves buta-1,3-diene (a conjugated diene) and bromine water (Br₂ in water). This is an electrophilic addition reaction, where bromine reacts with the double bonds in the diene system.

Analyze the structure of buta-1,3-diene: Buta-1,3-diene has two conjugated double bonds. The conjugation allows for resonance stabilization, which will influence the regioselectivity and stereochemistry of the reaction.

Determine the possible reaction pathways: Bromine can add to the diene in two ways: (1) 1,2-addition, where bromine adds across the first double bond, and (2) 1,4-addition, where bromine adds across the conjugated system, resulting in a product with a double bond shifted to the middle of the molecule.

Consider the reaction conditions: Bromine water is an aqueous solution, so the reaction may also involve the formation of bromohydrins (addition of Br and OH groups) due to the presence of water as a nucleophile. This can compete with the direct addition of bromine.

Draw the possible products: For 1,2-addition, the product will be 3,4-dibromobut-1-ene. For 1,4-addition, the product will be 1-bromo-2-buten-3-ol (if water participates) or 1,4-dibromobut-2-ene (if bromine adds directly). Ensure to account for stereochemistry in the products, as the addition of bromine can lead to anti-addition (trans products).

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Key Concepts

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

Diene Reactivity

Butadiene is a conjugated diene, which means it has alternating double bonds. This structure allows for greater stability and reactivity in electrophilic addition reactions. Understanding how dienes react with electrophiles, such as bromine, is crucial for predicting the products of the reaction.

Electrophilic Addition

Electrophilic addition is a fundamental reaction mechanism in organic chemistry where an electrophile reacts with a nucleophile, resulting in the formation of a more saturated product. In the case of buta-1,3-diene and bromine, the bromine acts as an electrophile, adding across the double bonds of the diene.

Regioselectivity

Regioselectivity refers to the preference of a chemical reaction to yield one structural isomer over others when multiple products are possible. In the reaction of buta-1,3-diene with bromine, the formation of different dibrominated products can occur, and understanding regioselectivity helps predict which product will be favored based on the stability of the intermediates formed during the reaction.

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Related Practice

Textbook Question

What are the major 1,2- and 1,4-addition products of the following reaction? Indicate the kinetic and the thermodynamic products.

Textbook Question

What are the products of the following reactions, assuming that one equivalent of each reagent is used in each reaction?

Textbook Question

A student wanted to know whether the greater proximity of the nucleophile to the C-2 carbon in the transition state is what causes the 1,2-addition product to be formed faster when 1,3-butadiene reacts with HCl. Therefore, she decided to investigate the reaction of 2-methyl-1,3-cyclohexadiene with HCl. Her friend told her that she should use 1-methyl-1,3-cyclohexadiene instead. Should she follow her friend's advice?

Textbook Question

The experiment shown next and discussed in Section 8.13 shows that the proximity of the chloride ion to C-2 in the transition state causes the 1,2-addition product to form more rapidly than the 1,4-addition product.

a. Why was it important for the investigators to know that the preceding reaction was being carried out under kinetic control?

Textbook Question

Predict the products of the following reactions.

(b) cyclopentadiene + anhydrous HCl

Textbook Question

Predict the products of the following reactions.

(f) hexa-1,3,5-triene + bromine in CCl₄

Textbook Question

The following diene gives the same product regardless of whether the reaction is run under conditions of kinetic (0 °C) or thermodynamic (100 °C) control. Predict the product and explain this observation.

Textbook Question

Would you expect the following nucleophiles to do 1,2- or 1,4-addition?

(g)

(h)

(i)

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