D-Glucose, D-Mannose and D-Fructose form same osazone on reaction with phenyl hydrazine because they have same confuguration at carbon x, y & z. Values of x,y and z are

Answer

To determine the values of x, y, and z for D-Glucose, D-Mannose, and D-Fructose that lead to the formation of the same osazone upon reaction with phenyl hydrazine, we need to analyze the structures of these sugars and identify the carbon atoms that have the same configuration.

### Step-by-Step Solution:

1. **Identify the Structures of D-Glucose, D-Mannose, and D-Fructose**:
- D-Glucose:
- Structure: C6H12O6
- Configuration:
- C1: Aldose (CHO)
- C2: OH on the right
- C3: OH on the right
- C4: OH on the left
- C5: OH on the right
- C6: CH2OH
- D-Mannose:
- Structure: C6H12O6
- Configuration:
- C1: Aldose (CHO)
- C2: OH on the left
- C3: OH on the right
- C4: OH on the left
- C5: OH on the right
- C6: CH2OH
- D-Fructose:
- Structure: C6H12O6
- Configuration:
- C2: Ketose (C=O)
- C3: OH on the right
- C4: OH on the left
- C5: OH on the right
- C6: CH2OH
- C1 and C2 are part of the ketone group.

2. **Identify the Carbons with Same Configuration**:
- For D-Glucose and D-Mannose, the configuration at C2, C3, and C4 differs, but they share the same configuration at C1 and C5.
- For D-Fructose, the configuration at C2 is different because it is a ketose, but it shares the same configuration at C3, C4, and C5 with D-Glucose and D-Mannose.

3. **Determine the Values of x, y, and z**:
- From the analysis, we find that:
- Carbon x = C2 (same configuration in D-Glucose and D-Mannose)
- Carbon y = C3 (same configuration in all three sugars)
- Carbon z = C4 (same configuration in D-Glucose and D-Mannose)
- Therefore, the values of x, y, and z are:
- x = 2
- y = 3
- z = 4

### Final Answer:
The values of x, y, and z are:
- x = 2
- y = 3
- z = 4