Polyurethanes:

Options

A. Have structure features of both an ester and an amide.
B. Have a formula`H_(2)N-underset(O)underset(||)(C )-O-CH_(2)-CH_(3)`.
C. Are obtianed from`p`-phenylene disocyanate and ethylene glycol.
D. Are used as foam rubber in upholstery.

Answer

### Step-by-Step Solution:

1. **Understanding Polyurethanes**:
Polyurethanes, commonly abbreviated as PUR or PU, are polymers that contain carbamate units, also known as urethane links or units.

2. **Identifying Monomers**:
The primary monomers used to synthesize polyurethanes are para-phenylene diisocyanate and ethylene glycol.
- Ethylene glycol has the chemical formula:
\[ \text{HO-CH}_2-\text{CH}_2-\text{OH} \]
- Para-phenylene diisocyanate can be represented as:
\[ \text{C}_6\text{H}_4(\text{NCO})_2 \]
This compound consists of a phenyl group with two isocyanate groups attached.

3. **Polymerization Process**:
When ethylene glycol reacts with para-phenylene diisocyanate, they undergo a polymerization reaction to form polyurethane. This reaction does not involve the formation of ester or amide linkages.

4. **Analyzing Statements**:
We need to evaluate the statements regarding the properties of polyurethanes:
- **Statement 1**: Polyurethanes contain ester or amide linkages.
- This statement is **false** since polyurethanes do not have these linkages.
- **Statement 2**: Polyurethanes are used in rubber or foam applications.
- This statement is **false** as polyurethanes are typically thermosetting polymers and not primarily used in rubber applications.
- **Statement 3**: Polyurethanes are obtained from phenylene diisocyanate and ethylene glycol.
- This statement is **true** and correctly describes the synthesis of polyurethanes.

5. **Conclusion**:
The only correct statement about polyurethanes is that they are obtained from phenylene diisocyanate and ethylene glycol, which corresponds to option C.

### Final Answer:
The correct statement regarding polyurethanes is option C: "Polyurethanes are obtained from phenylene diisocyanate and ethylene glycol."

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