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 \( C_5H_{12}O \), we will systematically explore the possible structural arrangements of the carbon skeleton and the placement of the hydroxyl (OH) group.

### Step 1: Identify the Carbon Skeleton
The first step is to identify the possible carbon skeletons for 5 carbon atoms. The main chain can be straight (pentane) or branched.

1. **Straight Chain (Pentane)**:
- 1-pentanol
- 2-pentanol
- 3-pentanol

### Step 2: Consider Branched Chains
Next, we will consider branched chains where one or more carbons are branched off the main chain.

2. **4-Carbon Chain with a Methyl Group**:
- 2-methyl-1-butanol
- 2-methyl-2-butanol
- 3-methyl-1-butanol
- 3-methyl-2-butanol

### Step 3: Consider Further Branching
Now we will consider the possibility of creating more branched structures.

3. **3-Carbon Chain with Two Methyl Groups**:
- 2,2-dimethylpropan-1-ol

### Step 4: Count All Isomers
Now we will count all the unique isomers we have identified:

1. **From the straight chain**:
- 1-pentanol
- 2-pentanol
- 3-pentanol

2. **From the branched chains**:
- 2-methyl-1-butanol
- 2-methyl-2-butanol
- 3-methyl-1-butanol
- 3-methyl-2-butanol
- 2,2-dimethylpropan-1-ol

### Total Count
Adding these together, we have:
- 3 (from straight chain) + 5 (from branched chains) = 8 isomeric alcohols.

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

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