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

7:43 minutes

Problem 55c2

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.

Verified step by step guidance

Understand the structure of diethyl carbonate (C5H10O3) and methyl isocyanate (CH3NCO). Diethyl carbonate contains two ethoxy groups (-OCH2CH3) attached to a central carbonyl group (C=O), while methyl isocyanate contains a methyl group (CH3) attached to an isocyanate functional group (-N=C=O).

Recall the structure of Sevin® insecticide, which is carbaryl (1-naphthyl N-methylcarbamate). It is synthesized by introducing a carbamate functional group (-NHCOO-) to a naphthol derivative. The goal is to replace methyl isocyanate with diethyl carbonate in this synthesis.

Propose a reaction mechanism where diethyl carbonate reacts with 1-naphthol (C10H7OH). The hydroxyl group (-OH) of 1-naphthol can act as a nucleophile, attacking the carbonyl carbon of diethyl carbonate, leading to the formation of an intermediate.

Account for the elimination of ethanol (C2H5OH) during the reaction. This occurs as the ethoxy group (-OCH2CH3) is displaced, leaving behind the desired carbamate functional group attached to the naphthol ring.

Verify the final product structure to ensure it matches the structure of Sevin® (1-naphthyl N-methylcarbamate). The reaction should yield the carbamate derivative of 1-naphthol, completing the synthesis using diethyl carbonate as a substitute for methyl isocyanate.

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Key Concepts

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

Diethyl Carbonate

Diethyl carbonate is an organic compound classified as a carbonate ester. It is a colorless, flammable liquid with a fruity odor, commonly used as a solvent and reagent in organic synthesis. Its structure allows it to participate in nucleophilic substitution reactions, making it a versatile building block in the synthesis of various organic compounds, including pharmaceuticals and agrochemicals.

Methyl Isocyanate

Methyl isocyanate (MIC) is a highly reactive organic compound known for its use in the production of pesticides, particularly carbamate insecticides like Sevin®. It is a toxic and volatile compound that can pose significant health risks. Understanding its reactivity and the mechanisms of its reactions is crucial for safely substituting it with less hazardous alternatives like diethyl carbonate in synthetic pathways.

Carbamate Insecticides

Carbamate insecticides are a class of chemicals derived from carbamic acid, known for their effectiveness in pest control. They work by inhibiting the enzyme acetylcholinesterase, leading to the accumulation of acetylcholine and resulting in paralysis of the target pests. Understanding the synthesis and action of carbamates is essential for developing safer alternatives and improving the environmental profile of insecticides.

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Related Practice

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.

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

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

(d)

Textbook Question

Predict the products of the following reactions.

(d) anisole + succinic anhydride and aluminum chloride

Textbook Question

Show how you would accomplish the following multistep syntheses. You may use any additional reagents and solvents you need.

(e)

Textbook Question

Write the mechanism for each of the following reactions: