Table of contents

Prepare for your exams

Upload your syllabus and get recommendations on what to study and when. No syllabus? Sharing your exam schedule works too.

Skip topic navigation

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

36. Synthetic Polymers

Step-Growth Polymers: Urethane

36. Synthetic Polymers

Step-Growth Polymers: Urethane: Videos & Practice Problems

Video Lessons Practice Worksheet

Topic summary

Urethane is a carbonate ester formed through the nucleophilic addition of an alcohol to an isocyanate. This reaction involves the carbonyl group of the isocyanate and the hydroxyl group of the alcohol, resulting in a carbamate ester. The nitrogen atom of the isocyanate accepts a hydrogen from the alcohol, while the remaining alkoxy group attaches to the carbonyl carbon, creating the urethane structure. Understanding this formation is essential for grasping the broader concepts of nucleophilic addition and the properties of carbonate esters in organic synthesis.

concept

Step-Growth Polymers: Urethane Concept 1

Video duration:

Play a video:

Was this helpful?

Step-Growth Polymers: Urethane Concept 1 Video Summary

Urethane formation involves the creation of a carbonate ester through a nucleophilic addition reaction. This process occurs when an alcohol reacts with an isocyanate molecule. A carbonate ester is characterized by a carbonyl group (C=O) that is bonded to an amino group (N) and an alkoxyl group (O-R), where R represents a carbon atom or hydrogen.

In the reaction, the isocyanate features a reactive carbon atom that is double-bonded to a nitrogen atom. When the alcohol approaches, the pi bond of the isocyanate is broken, allowing the alcohol to attach. Specifically, the hydrogen atom from the alcohol is transferred to the nitrogen atom, forming an NH bond. Meanwhile, the remaining alkoxyl portion (O-R) of the alcohol bonds to the carbonyl carbon, resulting in the formation of the urethane structure.

This reaction can be summarized as follows: the isocyanate (R-N=C=O) reacts with the alcohol (R'-OH) to yield the urethane (R-NH-C(=O)-O-R'). This simplified explanation highlights the essential components of urethane formation without delving into the detailed reaction mechanism.

example

Step-Growth Polymers: Urethane Example 1

Video duration:

Play a video:

Was this helpful?

Step-Growth Polymers: Urethane Example 1 Video Summary

In the reaction between isocyanate and sec-butyl alcohol, the structure of the resulting product can be understood by examining the components involved. Isocyanate has the general structure where nitrogen is double bonded to carbon, which is also double bonded to oxygen (R-N=C=O). When it reacts with sec-butyl alcohol, which has the structure of a secondary alcohol (R-OH), the hydrogen from the alcohol transfers to the nitrogen of the isocyanate.

This transfer results in the breaking of the pi bond between the nitrogen and carbon, leading to a single bond between them. The carbon remains double bonded to the oxygen, while the oxygen from the alcohol forms a new bond with the carbon of the isocyanate. The sec-butyl alcohol can be represented as follows: CH₃CH(OH)CH₂CH₃.

After the reaction, the product formed is a urethane, which can be described as a carbonate ester. The final structure includes the nitrogen atom bonded to the carbon that is also bonded to the oxygen from the alcohol, along with the remaining carbon chain from the sec-butyl alcohol. This product can be represented as follows:

R-NH-C(=O)-O-R'

Where R is the sec-butyl group and R' is the remaining part of the isocyanate. This reaction exemplifies the formation of urethanes, which are important in various applications, including the production of foams, elastomers, and coatings.

Problem

Provide the structure of the urethane molecule created from the reaction between phenyl isocyanate and ethylene diol.

Video duration:

Play a video:

Was this helpful?

Problem

Name the alcohol that was used to create the following urethane molecule.

(1S,3S)-3-methyl-1-cyclopentanol

(1S,3R)-3-methyl-1-cyclopentanol

(1R,3S)-3-methyl-1-cyclopentanol

(1R,3R)-3-methyl-1-cyclopentanol

Do you want more practice?

We have more practice problems on Step-Growth Polymers: Urethane

Here’s what students ask on this topic:

What is the mechanism of urethane formation from an alcohol and an isocyanate?

Urethane formation involves the nucleophilic addition of an alcohol to an isocyanate. The mechanism starts with the nucleophilic attack of the alcohol's hydroxyl group on the carbonyl carbon of the isocyanate. This results in the formation of a tetrahedral intermediate. The nitrogen atom of the isocyanate then accepts a hydrogen from the alcohol, forming an NH group. The remaining alkoxy group (RO) from the alcohol attaches to the carbonyl carbon, creating the urethane structure. The overall reaction can be summarized as:

$R_{1} - N = C = O + R_{2} - OH \to R_{1} - N (H)- C (O)- O_{R} 2$

What are the key functional groups involved in urethane formation?

The key functional groups involved in urethane formation are the isocyanate group (N=C=O) and the hydroxyl group (OH) of an alcohol. The isocyanate group contains a carbonyl carbon (C=O) and a nitrogen atom (N), while the hydroxyl group consists of an oxygen atom bonded to a hydrogen atom. During the reaction, the hydroxyl group of the alcohol attacks the carbonyl carbon of the isocyanate, leading to the formation of a carbamate ester (urethane), which has the general structure R1-NH-C(O)-OR2.

What is the significance of urethane formation in organic synthesis?

Urethane formation is significant in organic synthesis because it provides a versatile method for creating carbamate esters, which are important intermediates in the production of pharmaceuticals, agrochemicals, and polymers. Urethanes are also used in the manufacture of polyurethane foams, coatings, and elastomers. Understanding the formation of urethanes helps chemists design and synthesize new materials with desired properties, making it a crucial reaction in both academic research and industrial applications.

How does the nucleophilic addition mechanism apply to urethane formation?

The nucleophilic addition mechanism in urethane formation involves the attack of a nucleophile (the hydroxyl group of an alcohol) on an electrophile (the carbonyl carbon of an isocyanate). The nucleophile donates a pair of electrons to the electrophile, forming a new covalent bond. In this case, the hydroxyl group attacks the carbonyl carbon, creating a tetrahedral intermediate. The nitrogen atom of the isocyanate then accepts a hydrogen from the alcohol, resulting in the formation of an NH group. The remaining alkoxy group attaches to the carbonyl carbon, completing the urethane structure. This mechanism is a fundamental concept in organic chemistry, illustrating how nucleophiles and electrophiles interact to form new compounds.

What are the applications of urethane in industry?

Urethane has numerous applications in industry, primarily due to its versatility and desirable properties. It is widely used in the production of polyurethane foams, which are essential for insulation, cushioning, and packaging. Urethanes are also used in coatings, adhesives, sealants, and elastomers, providing durability, flexibility, and resistance to chemicals and abrasion. Additionally, urethanes are important in the manufacture of synthetic fibers, automotive parts, and medical devices. Their ability to form strong, stable bonds makes them valuable in various industrial applications, contributing to advancements in materials science and engineering.