The total number of ketones (including stereo isomers ) with the molecular formula `C_(6)H_(12)O` is :

Options

A. 4
B. 5
C. 6
D. 7

Answer

To determine the total number of ketones (including stereoisomers) with the molecular formula C₆H₁₂O, we can follow these steps:

### Step 1: Understand the Structure of Ketones
Ketones have the general structure R-CO-R', where R and R' are carbon-containing groups. For a ketone with the formula C₆H₁₂O, we need to have a carbonyl group (C=O) flanked by two carbon chains.

### Step 2: Determine the Carbon Skeletons
We need to find different carbon skeletons that can give rise to ketones. The carbon skeletons can vary in terms of branching and linear arrangements.

1. **Linear Structure**: Start with a straight-chain of 6 carbon atoms.
2. **Branched Structures**: Consider branching at various positions to create different ketone structures.

### Step 3: Draw Possible Ketone Structures
1. **Straight-chain (Hexan-2-one)**: CH₃(CH₂)₄COCH₃
2. **Branched Structures**:
- 2-Pentanone (with a methyl group on the second carbon)
- 3-Pentanone (with a methyl group on the third carbon)
- 4-Methyl-2-pentanone (with a methyl group on the fourth carbon)
- 3-Hexanone (with a methyl group on the third carbon of a hexane chain)
- 2-Hexanone (with a methyl group on the second carbon of a hexane chain)

### Step 4: Identify Chiral Centers
While drawing the structures, identify any chiral centers:
- A chiral center is a carbon atom that is bonded to four different groups. For example, in 4-Methyl-2-pentanone, the carbon adjacent to the carbonyl group can be a chiral center.

### Step 5: Count Stereoisomers
For each chiral center, there can be two stereoisomers (R and S configurations).
- For example, if one structure has one chiral center, it contributes two stereoisomers.

### Step 6: Total Count of Ketones
After drawing all possible structures and identifying chiral centers, count the total number of unique ketone structures including stereoisomers.

1. **Count of Ketones**:
- Hexan-2-one: 1 structure
- 3-Pentanone: 1 structure
- 2-Pentanone: 1 structure
- 4-Methyl-2-pentanone: 2 structures (due to chirality)
- 3-Hexanone: 1 structure
- 2-Hexanone: 1 structure

### Conclusion
After counting all unique structures and considering stereoisomers, the total number of ketones with the molecular formula C₆H₁₂O is **7**.