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)

Previous problemNext problem

3:16 minutes

Problem 36g,h,i

Textbook Question

Would you expect the following nucleophiles to do 1,2- or 1,4-addition?
(g)
(h)
(i)

Verified step by step guidance

Identify the type of nucleophile: Determine whether the nucleophile is a strong or weak nucleophile. Strong nucleophiles tend to favor 1,2-addition, while weak nucleophiles often favor 1,4-addition.

Analyze the electrophile: Consider the structure of the electrophile, particularly if it is an α,β-unsaturated carbonyl compound. This will help determine the possible sites for nucleophilic attack.

Consider the reaction conditions: The conditions under which the reaction is carried out (e.g., temperature, solvent) can influence whether 1,2- or 1,4-addition is favored.

Evaluate the stability of intermediates: 1,4-addition often leads to more stable intermediates, such as enolates or enols, which can be a deciding factor in the reaction pathway.

Predict the outcome: Based on the analysis of the nucleophile, electrophile, and reaction conditions, predict whether 1,2- or 1,4-addition is more likely to occur for each nucleophile.

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.

Nucleophiles

Nucleophiles are species that donate an electron pair to form a chemical bond in reaction mechanisms. They are typically negatively charged or neutral molecules with lone pairs of electrons. Understanding the nature of nucleophiles, such as their charge, size, and electron density, is crucial for predicting their behavior in addition reactions.

1,2-Addition

1,2-Addition, also known as direct addition, occurs when a nucleophile adds to the carbon atom directly adjacent to the carbonyl group in an α,β-unsaturated carbonyl compound. This type of addition is favored by strong, small nucleophiles and results in the formation of a new bond at the carbonyl carbon, often leading to a more stable product in kinetic terms.

1,4-Addition

1,4-Addition, or conjugate addition, involves the nucleophile adding to the β-carbon of an α,β-unsaturated carbonyl compound. This pathway is typically favored by weaker, larger nucleophiles and results in the formation of a more stable product in thermodynamic terms. Understanding the conditions and nucleophile characteristics that favor 1,4-addition is essential for predicting reaction outcomes.

Watch next

Master Conjugated Hydrohalogenation - General Mechanism with a bite sized video explanation from Johnny

Start learning

Related Videos

Related Practice

Textbook Question

Predict the products of the following reactions.

(e) buta-1,3-diene + bromine water

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

What products would be obtained from the reaction of 1,3,5-hexatriene with one equivalent of HBr? Disregard stereoisomers.

Textbook Question

Whereas stabilized enolates do 1,4-addition, unstabilized (normal) enolates can do both 1,2- and 1,4-addition depending on the situation. Why might this be?

Textbook Question

Predict the product of the following addition reactions to dienes.

(a)

Textbook Question

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

Show more practices