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

3:12 minutes

Problem 51a

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.

(a) Predict the products formed when phosgene reacts with excess propan-2-ol.

Verified step by step guidance

Step 1: Recognize the structure of phosgene (Cl₂C=O), which is an acid chloride derived from carbonic acid. Acid chlorides are reactive electrophiles that undergo nucleophilic acyl substitution reactions.

Step 2: Identify the nucleophile in the reaction. In this case, excess propan-2-ol (CH₃CHOHCH₃) acts as the nucleophile. Alcohols are good nucleophiles due to the lone pairs on the oxygen atom.

Step 3: Predict the first reaction step. The nucleophilic oxygen of propan-2-ol attacks the carbonyl carbon of phosgene, displacing one chloride ion (Cl^-) and forming an intermediate ester-like compound: CH₃CHOHCH₃-C(=O)-Cl.

Step 4: Predict the second reaction step. Since phosgene can react twice, another molecule of propan-2-ol attacks the remaining carbonyl chloride group in the intermediate, displacing the second chloride ion (Cl^-) and forming the final product: CH₃CHOHCH₃-C(=O)-OCH₃CHOHCH₃.

Step 5: Summarize the reaction. The final products are a diester (formed by two molecules of propan-2-ol reacting with phosgene) and two chloride ions (Cl^-) as byproducts.

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.

Nucleophilic Acyl Substitution

Nucleophilic acyl substitution is a fundamental reaction in organic chemistry where a nucleophile attacks the carbonyl carbon of an acyl compound, leading to the replacement of a leaving group. In the case of phosgene, the nucleophile (propan-2-ol) attacks the carbonyl carbon, resulting in the formation of a tetrahedral intermediate that eventually collapses to yield a carboxylic acid derivative and release the leaving group.

Acid Chlorides

Acid chlorides are a class of reactive organic compounds characterized by the presence of a carbonyl group (C=O) bonded to a chlorine atom. They are highly reactive due to the electronegative chlorine, which makes the carbonyl carbon more susceptible to nucleophilic attack. Phosgene, as an acid chloride of carbonic acid, exhibits similar reactivity, allowing it to participate in nucleophilic acyl substitution reactions.

Reactivity of Phosgene

Phosgene is notable for its ability to react twice with nucleophiles due to its two reactive acyl chloride groups. This property allows it to form products with two nucleophiles, such as propan-2-ol, leading to the generation of a diester. Understanding this reactivity is crucial for predicting the products of reactions involving phosgene and other similar acid chlorides.

Watch next

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

Start learning

Related Videos

Related Practice

Textbook Question

Show how you would use anhydrides to synthesize the following compounds. In each case, explain why an anhydride might be preferable to an acid chloride.

(d) succinic acid monomethyl ester

Textbook Question

Predict the major products formed when benzoyl chloride (PhCOCl) reacts with the following reagents.

(d) anisole and aluminum chloride

(e) excess phenylmagnesium bromide, then dilute acid

(f) LiAlH(O-t-Bu)₃

Textbook Question

Predict the products of the following reactions.

(e)

(f)

Textbook Question

One mole of acetyl chloride is added to a liter of triethylamine, resulting in a vigorous exothermic reaction. Once the reaction mixture has cooled, 1 mole of ethanol is added. Another vigorous exothermic reaction results. The mixture is analyzed and found to contain triethylamine, ethyl acetate, and triethylammonium chloride. Propose mechanisms for the two exothermic reactions.

Textbook Question

In each part, rank the compounds in order of increasing rate of nucleophilic attack at C=O by a strong nucleophile like methoxide.

(b)

Textbook Question

Suggest the most appropriate reagent for each synthesis, and explain your choice.

(a)

Textbook Question

There are many methods for activating a carboxylic acid in preparation for coupling with an amine. The following method converts the acid to an N-hydroxysuccinimide (NHS) ester.

(a) Explain why an NHS ester is much more reactive than a simple alkyl ester.

Textbook Question

Grignard reagents add to carbonate esters as they add to other esters.

(c) Diethyl carbonate is a liquid reagent that is easy to handle. Also show how you might use diethyl carbonate instead of methyl isocyanate to make Sevin® insecticide.

Show more practices

Download the Mobile app

Privacy

Do not sell my personal information

Accessibility

Patent notice

Sitemap