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

22. Carboxylic Acid Derivatives: NAS

Carboxylic Acid Derivatives

Organic Chemistry

22. Carboxylic Acid Derivatives: NAS

Carboxylic Acid Derivatives

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3:35 minutes

Problem 38b

Textbook Question

Show how you would convert the following starting materials to the indicated nitriles:
(b) phenylacetic acid → 3-phenylpropionitrile

Verified step by step guidance

Step 1: Begin by understanding the transformation required. The starting material is phenylacetic acid (C₆H₅CH₂COOH), and the target product is 3-phenylpropionitrile (C₆H₅CH₂CH₂CN). This involves replacing the carboxylic acid (-COOH) group with a nitrile (-CN) group while extending the carbon chain by one methylene (-CH₂-) group.

Step 2: Convert phenylacetic acid into phenylacetyl chloride (C₆H₅CH₂COCl) using thionyl chloride (SOCl₂). This reaction replaces the hydroxyl group (-OH) of the carboxylic acid with a chlorine atom, forming an acyl chloride. The reaction proceeds via nucleophilic substitution.

Step 3: Perform a reaction with ammonia (NH₃) to convert phenylacetyl chloride into phenylacetamide (C₆H₅CH₂CONH₂). Ammonia acts as a nucleophile, attacking the acyl chloride to form the amide. This step introduces the nitrogen atom required for the nitrile group.

Step 4: Subject phenylacetamide to dehydration using a dehydrating agent such as phosphorus pentoxide (P₂O₅) or thionyl chloride (SOCl₂). This step removes water from the amide, converting it into phenylacetonitrile (C₆H₅CH₂CN).

Step 5: Perform a homologation reaction to extend the carbon chain by one methylene group. React phenylacetonitrile with sodium cyanide (NaCN) and an alkyl halide, such as ethyl bromide (C₂H₅Br), under basic conditions. This introduces the additional -CH₂- group, yielding 3-phenylpropionitrile (C₆H₅CH₂CH₂CN).

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Key Concepts

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

Nitrile Synthesis

Nitriles are organic compounds containing a cyano group (-C≡N). One common method to synthesize nitriles is through the conversion of carboxylic acids or their derivatives. In this case, phenylacetic acid can be transformed into a nitrile by first converting it to an acid chloride and then reacting it with a suitable nucleophile, such as sodium cyanide.

Reagents and Reaction Conditions

The choice of reagents and reaction conditions is crucial in organic synthesis. For converting phenylacetic acid to 3-phenylpropionitrile, reagents like thionyl chloride (SOCl2) or oxalyl chloride (COCl) can be used to form the acid chloride. Following this, a nucleophilic substitution reaction with sodium cyanide will yield the desired nitrile product.

Mechanism of Nucleophilic Substitution

Nucleophilic substitution reactions involve the attack of a nucleophile on an electrophile, leading to the replacement of a leaving group. In the case of converting an acid chloride to a nitrile, the cyanide ion acts as the nucleophile, attacking the carbonyl carbon of the acid chloride, resulting in the formation of the nitrile while releasing chloride ions as a byproduct.

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Show how you would synthesize octan-2-one from each compound. You may use any necessary reagents.

(e) heptanoic acid

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(A true story.) Chemistry lab students added an excess of ethylmagnesium bromide to methyl furoate, expecting the Grignard reagent to add twice and form the tertiary alcohol. After water workup, they found that the product was a mixture of two compounds. One was the expected product having two ethyl groups, but the unexpected product had added three ethyl groups. Propose a mechanism to explain the formation of the unexpected product.

Textbook Question

Show how you would accomplish the following syntheses efficiently (you may use any necessary reagents).

(e)

Textbook Question

Show how you would accomplish the following syntheses efficiently (you may use any necessary reagents).

(g)

Textbook Question

Show how you would convert the following starting materials to the indicated nitriles:

Textbook Question

Show how you would accomplish the following syntheses in good yields.

(a)

Textbook Question