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

Nucleophilic Acyl Substitution

Organic Chemistry

22. Carboxylic Acid Derivatives: NAS

Nucleophilic Acyl Substitution

Previous problemNext problem

3:22 minutes

Problem 51b

Textbook Question

Phosgene is the acid chloride of carbonic acid. Although phosgene was used as a war gas in World War I, it is now used as a reagent for the synthesis of many useful products. Phosgene reacts like other acid chlorides, but it can react twice.

(b) Predict the products formed when phosgene reacts with 1 equivalent of methanol, followed by 1 equivalent of aniline.

Verified step by step guidance

Step 1: Understand the reactivity of phosgene. Phosgene (Cl₂C=O) is an acid chloride and reacts with nucleophiles. It can undergo two successive nucleophilic acyl substitution reactions due to the presence of two chlorine atoms attached to the carbonyl carbon.

Step 2: Analyze the reaction with methanol. Methanol (CH₃OH) acts as a nucleophile. The lone pair on the oxygen atom of methanol attacks the carbonyl carbon of phosgene, displacing one chloride ion (Cl^-). This forms methyl chloroformate (CH₃OCOCl).

Step 3: Examine the reaction with aniline. Aniline (C₆H₅NH₂) is a nucleophile due to the lone pair on the nitrogen atom. Aniline reacts with methyl chloroformate, attacking the carbonyl carbon and displacing the remaining chloride ion (Cl^-). This forms the final product, methyl N-phenyl carbamate (CH₃OCO-NH-C₆H₅).

Step 4: Summarize the reaction mechanism. The reaction proceeds via two nucleophilic acyl substitution steps. In the first step, methanol replaces one chloride ion, forming methyl chloroformate. In the second step, aniline replaces the remaining chloride ion, forming methyl N-phenyl carbamate.

Step 5: Note the byproducts. Each substitution reaction releases a chloride ion (Cl^-) as a byproduct. Therefore, two chloride ions are released in total during the reaction.

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.

Acid Chlorides

Acid chlorides are a class of organic compounds derived from carboxylic acids, where the hydroxyl group (-OH) is replaced by a chlorine atom. They are highly reactive due to the presence of the carbonyl group (C=O) and the electronegative chlorine, making them excellent electrophiles. This reactivity allows them to participate in nucleophilic acyl substitution reactions, where nucleophiles attack the carbonyl carbon, leading to the formation of various products.

Nucleophilic Acyl Substitution

Nucleophilic acyl substitution is a fundamental reaction in organic chemistry where a nucleophile attacks the electrophilic carbon of a carbonyl group in an acyl compound, such as an acid chloride. This reaction typically involves the replacement of a leaving group (like Cl) with the nucleophile. In the case of phosgene reacting with methanol and aniline, the nucleophiles will replace the chlorine atoms, resulting in the formation of esters and amides.

Reactivity of Phosgene

Phosgene, as an acid chloride of carbonic acid, exhibits unique reactivity patterns due to its ability to undergo two nucleophilic substitutions. When it reacts with nucleophiles like methanol and aniline, it can form both an ester and an amide. Understanding this dual reactivity is crucial for predicting the products of the reaction, as it highlights the versatility of phosgene in synthetic organic chemistry.

Watch next

Master NAS - The Three Rules with a bite sized video explanation from Johnny

Start learning