`CH_(3)CH_(2)CH(OH)CH(CH_(3))_(2)+CH_(3)COCI overset("base")rarr CH_(3)CH_(2)CH(OCOCH_(3))CH(CH_(3))_(2)+HCI` In the above reaction, if the reactant alcohol is a pure R-isomer the product would.

Options

A. Have configuration inverted at the chiral atom
B. be a racemic mixture
C. have the same configuration at the chiral atom
D. be optically inactive

Answer

To solve the problem, we need to analyze the reaction step by step, focusing on the stereochemistry involved when the reactant alcohol is a pure R-isomer.

### Step-by-Step Solution:

1. **Identify the Reactant Structure:**
The reactant is an alcohol with the structure CH3CH2CH(OH)CH(CH3)2. The hydroxyl (OH) group is attached to the third carbon, which makes this carbon a chiral center because it is bonded to four different groups:
- CH3 (methyl group)
- CH2CH3 (ethyl group)
- OH (hydroxyl group)
- H (hydrogen atom)

2. **Determine the Configuration of the Chiral Center:**
Since the reactant is specified as a pure R-isomer, we can assign the configuration at the chiral center. The priority of the substituents is determined by atomic number:
- OH has the highest priority (1)
- CH3 (methyl) is second (2)
- CH2CH3 (ethyl) is third (3)
- H (hydrogen) is lowest (4)

When arranged in order of priority, if you trace a path from 1 to 2 to 3, it goes in a clockwise direction, confirming that it is indeed an R configuration.

3. **Reaction with Acetyl Chloride:**
The alcohol reacts with acetyl chloride (CH3COCl) in the presence of a base. The base helps in the nucleophilic attack of the hydroxyl oxygen on the carbonyl carbon of acetyl chloride, leading to the formation of an intermediate.

4. **Formation of the Product:**
The product formed will have the structure CH3CH2CH(OCOCH3)CH(CH3)2. The carbon that was originally the chiral center now has a new substituent (OCOCH3) replacing the OH group.

5. **Analyze the New Chiral Center:**
The new chiral center still has four different groups:
- OCOCH3 (acetyl group)
- CH2CH3 (ethyl group)
- CH(CH3)2 (isopropyl group)
- H (hydrogen atom)

The configuration at this new chiral center needs to be determined. The reaction mechanism involves the inversion of configuration at the chiral center due to the nucleophilic attack.

6. **Conclusion on Stereochemistry:**
Since the reaction involves the inversion of configuration at the chiral center, the product will have the opposite configuration compared to the reactant. Therefore, if the reactant is a pure R-isomer, the product will be an S-isomer.

### Final Answer:
If the reactant alcohol is a pure R-isomer, the product would have the configuration inverted at the chiral carbon atom, resulting in an S-isomer.