total number of isomeric alcohols (excluding stereoisomerism) with formula `C_5H_12O` is

Options

A. 5
B. 6
C. 7
D. 8

Answer

To determine the total number of isomeric alcohols with the molecular formula \( C_5H_{12}O \) (excluding stereoisomerism), we will follow these steps:

### Step 1: Identify the Base Structure
The base structure for alcohols with the formula \( C_5H_{12}O \) is a straight-chain or branched alkane with a hydroxyl (-OH) group. The longest carbon chain can have 5 carbon atoms.

### Step 2: Create Straight-Chain Alcohols
1. **Pentane-1-ol**: The hydroxyl group is at the end of the chain.
2. **Pentane-2-ol**: The hydroxyl group is on the second carbon.
3. **Pentane-3-ol**: The hydroxyl group is on the third carbon.

These three structures represent the straight-chain alcohols.

### Step 3: Create Branched Alcohols
Next, we will create branched alcohols by introducing methyl groups into the structure.

1. **3-Methylbutan-1-ol**: A methyl group on the third carbon of a butane chain with the -OH on the first carbon.
2. **3-Methylbutan-2-ol**: A methyl group on the third carbon of a butane chain with the -OH on the second carbon.
3. **2-Methylbutan-2-ol**: A methyl group on the second carbon of a butane chain with the -OH on the second carbon.
4. **2-Methylbutan-1-ol**: A methyl group on the second carbon of a butane chain with the -OH on the first carbon.
5. **2-Methylbutan-3-ol**: A methyl group on the second carbon of a butane chain with the -OH on the third carbon.

### Step 4: Count All Isomers
Now, we will count all the isomers we have created:
- From the straight-chain alcohols: 3 (Pentane-1-ol, Pentane-2-ol, Pentane-3-ol)
- From the branched alcohols: 5 (3-Methylbutan-1-ol, 3-Methylbutan-2-ol, 2-Methylbutan-2-ol, 2-Methylbutan-1-ol, 2-Methylbutan-3-ol)

### Step 5: Total Isomers
Adding these together gives:
\[ 3 + 5 = 8 \]

Thus, the total number of isomeric alcohols (excluding stereoisomerism) with the formula \( C_5H_{12}O \) is **8**.

### Final Answer
The total number of isomeric alcohols with the formula \( C_5H_{12}O \) is **8**.

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