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

19. Reactions of Aromatics: EAS and Beyond

Side-Chain Halogenation

Organic Chemistry

19. Reactions of Aromatics: EAS and Beyond

Side-Chain Halogenation

Previous problemNext problem

4:37 minutes

Problem 30c

Textbook Question

Show how you would convert (in one or two steps) 1-phenylpropane to the three products shown below. In each case, explain what unwanted reactions might produce undesirable impurities in the product.

Verified step by step guidance

Step 1: Analyze the starting material, 1-phenylpropane, and the target product, 2-phenylbutanenitrile. The transformation involves the addition of a nitrile group (-C≡N) to the carbon adjacent to the phenyl group, which requires a nucleophilic substitution reaction.

Step 2: Perform bromination of 1-phenylpropane using bromine (Br₂) in the presence of light or heat (radical halogenation conditions). This will selectively brominate the benzylic position (the carbon adjacent to the phenyl group) due to the stability of the benzylic radical intermediate. The product will be 1-bromo-2-phenylpropane.

Step 3: React 1-bromo-2-phenylpropane with sodium cyanide (NaCN) in a polar aprotic solvent like DMSO or acetone. This will result in an SN2 reaction, where the bromine atom is replaced by the cyanide group (-C≡N), forming 2-phenylbutanenitrile.

Step 4: Consider potential side reactions. During bromination, over-bromination (e.g., dibromination) or bromination at non-benzylic positions could occur, leading to impurities. During the SN2 reaction, elimination reactions (E2) might compete, forming alkenes as side products.

Step 5: To minimize impurities, ensure controlled reaction conditions: use excess bromine for selective benzylic bromination and avoid strong bases during the SN2 reaction to suppress elimination pathways.

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.

Nitrile Formation

Nitriles are organic compounds containing a cyano group (-C≡N). To convert 1-phenylpropane to 2-phenylbutanenitrile, a common method is to perform a nucleophilic substitution or addition reaction, where a suitable reagent, such as a cyanide ion, is introduced to form the nitrile. Understanding the mechanism of this transformation is crucial for predicting the reaction pathway and the conditions required.

Unwanted Side Reactions

In organic reactions, unwanted side reactions can lead to impurities in the final product. For instance, during the conversion of 1-phenylpropane to 2-phenylbutanenitrile, side reactions such as elimination or rearrangement may occur, resulting in by-products. Identifying these potential side reactions helps in optimizing reaction conditions to minimize impurities.

Reagent Selection

The choice of reagents is critical in organic synthesis, as it influences both the efficiency and selectivity of the reaction. In the case of converting 1-phenylpropane to 2-phenylbutanenitrile, selecting a suitable cyanide source and reaction conditions (like temperature and solvent) is essential to ensure a high yield of the desired product while reducing the formation of undesired by-products.

Watch next

Master Side-Chain Halogenations with a bite sized video explanation from Johnny

Start learning

Related Videos

Related Practice

Textbook Question

(c) Based on what you know about the relative stabilities of alkyl radicals and benzylic radicals, predict the product of addition of HBr to 1-phenylpropene in the presence of a free-radical initiator.

(d) Propose a mechanism for this reaction.

Textbook Question

Suggest reagents and reaction conditions that would result in synthesis of the following bromoalkanes.

(c)

Textbook Question

Predict the product of the following benzylic bromination reactions.

(c)

Textbook Question

What is the major product of the following reactions? Disregard stereoisomers:

Textbook Question

Show the products you expect when each compound reacts with NBS with light shining on the reaction.

(d)

Textbook Question

Predict the major products of treating the following compounds with hot, concentrated potassium permanganate, followed by acidification with dilute HCl.

(a) isopropylbenzene

(b) p-xylene

(c)

Textbook Question

Predict the product of the following benzylic bromination reactions.

(a)

Textbook Question

A radical reaction, as it progressed through its propagation steps, involved the following radical species. Suggest which products might form in all possible termination steps (six products are possible).

Show more practices

Download the Mobile app

Privacy

Do not sell my personal information

Accessibility

Patent notice

Sitemap