The monomer unit of PHBV is

Options

A. `CH_(3)-overset(OH)overset(|)(CH)-CH_(2)COOH`
B. `CH_(3)-CH_(2)-underset(OH)underset(|)(CH)-CH_(2)COOH`
C. `HO-CH_(2)-CH_(2)-COOH`
D. Both 1 and 2

Answer

To determine the monomer unit of PHBV (poly-beta-hydroxybutyrate-co-beta-hydroxyvalerate), we can follow these steps:

### Step-by-Step Solution:

1. **Understanding PHBV**:
- PHBV stands for poly-beta-hydroxybutyrate-co-beta-hydroxyvalerate. It is a type of biodegradable polymer.

2. **Identifying the Monomers**:
- The name suggests that PHBV is made from two different monomer units:
- The first monomer is **3-hydroxybutanoic acid** (which corresponds to beta-hydroxybutyrate).
- The second monomer is **3-hydroxyvaleric acid** (which corresponds to beta-hydroxyvalerate).

3. **Chemical Structure of Monomers**:
- **3-Hydroxybutanoic acid** has the structure:
- CH3-CH(OH)-CH2-COOH
- **3-Hydroxyvaleric acid** has the structure:
- CH3-CH2-CH(OH)-CH2-COOH

4. **Formation of PHBV**:
- When these two monomers undergo polymerization, they form the polymer PHBV. The reaction involves the condensation of the hydroxyl (-OH) group of one monomer with the carboxylic acid (-COOH) group of another, resulting in the formation of ester bonds and the release of water.

5. **Repeating Units**:
- The resulting structure of PHBV consists of repeating units of these two monomers, leading to a copolymer.

### Final Answer:
The monomer units of PHBV are **3-hydroxybutanoic acid** and **3-hydroxyvaleric acid**.

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