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

10. Addition Reactions

Hydrohalogenation

Organic Chemistry

10. Addition Reactions

Hydrohalogenation

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1:32 minutes

Problem 18e

Textbook Question

Show how hex-1-yne might be converted to
e. 2-bromohexane.

Verified step by step guidance

Identify the starting material (hex-1-yne) and the target product (2-bromohexane). Hex-1-yne is an alkyne, and 2-bromohexane is an alkane with a bromine atom on the second carbon. This suggests a multi-step reaction involving reduction and halogenation.

Step 1: Perform a partial reduction of hex-1-yne to hex-1-ene. Use a Lindlar catalyst (Pd/CaCO₃ poisoned with lead or quinoline) and hydrogen gas (H₂). This will selectively reduce the alkyne to a cis-alkene without further reducing it to an alkane.

Step 2: Carry out a hydrohalogenation reaction to add a bromine atom to the second carbon of the hex-1-ene. Use HBr (hydrobromic acid) as the reagent. According to Markovnikov's rule, the bromine will add to the more substituted carbon (C-2), while the hydrogen will add to the less substituted carbon (C-1).

Step 3: Verify the product structure. The resulting compound should be 2-bromohexane, with the bromine atom attached to the second carbon of the hexane chain.

Step 4: Purify the product if necessary, using techniques such as distillation or recrystallization, to isolate 2-bromohexane in its pure form.

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Key Concepts

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

Alkyne Reactivity

Alkynes, such as hex-1-yne, are hydrocarbons containing a carbon-carbon triple bond. This triple bond makes them more reactive than alkenes and alkanes, allowing them to undergo various reactions, including halogenation. Understanding the reactivity of alkynes is crucial for predicting the products of their reactions.

Halogenation

Halogenation is a chemical reaction where halogens (like bromine) are added to a compound. In the case of converting hex-1-yne to 2-bromohexane, the triple bond can be converted to a double bond through partial hydrogenation, followed by the addition of bromine. This process is essential for introducing halogen substituents into organic molecules.

Markovnikov's Rule

Markovnikov's Rule states that in the addition of HX (where X is a halogen) to an alkene, the hydrogen atom will attach to the carbon with the greater number of hydrogen atoms already attached. This principle helps predict the regioselectivity of the reaction, guiding the formation of 2-bromohexane from hex-1-yne by favoring the more stable carbocation during the reaction.

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Textbook Question

What is the major product of the reaction of each of the following with HBr?

Textbook Question

When 1-chlorocyclohexene reacts with HBr, the major product is 1-bromo-1-chlorocyclohexane. Propose a mechanism for this reaction, and explain why your proposed intermediate is more stable than the other possible intermediate

Textbook Question

Propose mechanisms consistent with the following reactions.

(c)

Textbook Question

(a) Based on what you know about the relative stabilities of alkyl cations and benzylic cations, predict the product of addition of HBr to 1-phenylpropene.

(b) Propose a mechanism for this reaction.

Textbook Question

Limonene is one of the compounds that give lemons their tangy odor. Show the structures of the products expected when limonene reacts with an excess of each of these reagents.

(i) hydrogen bromide gas in a solution containing dimethyl peroxide

Textbook Question

When 3-methyl-1-butene reacts with HBr, two alkyl halides are formed: 2-bromo-3-methylbutane and 2-bromo-2-methylbutane. Propose a mechanism that explains the formation of these two products.

Textbook Question

Predict the product of the following haloalkane syntheses.

Textbook Question

Predict the product(s) that would result when the alkenes shown here are allowed to react under the following conditions: (iii) HBr, H₂O₂

(g)

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