Which of the following compounds can exhibit tautomerism?

Options

A. `C_(6)H_(5)CHO`
B. `C_(6)H_(5)- overset(O) overset(||)(C)-CMe_(3)`
C. `C_(6)H_(5)- overset(O) overset(||)(C)-CH_(2)- overset(O) overset(||)(C)-H`
D. `C_(6)H_(5)- overset(O) overset(||)(C)-C_(6)H_(5)`

Answer

To determine which of the given compounds can exhibit tautomerism, we need to analyze each compound for the presence of alpha hydrogens. Tautomerism typically occurs in carbonyl compounds that have at least one alpha hydrogen adjacent to the carbonyl group. Here’s a step-by-step solution:

### Step 1: Understand Tautomerism
Tautomerism is a chemical phenomenon where a compound can exist in two interconvertible forms, typically involving the migration of a hydrogen atom and a shift of a double bond. The most common type of tautomerism in carbonyl compounds is keto-enol tautomerism.

### Step 2: Identify the Compounds
The options provided are:
- A: C6H5CHO (Benzaldehyde)
- B: C6H5C(=O)C(CH3)3 (A ketone with tert-butyl group)
- C: C6H5COCH2COH (A diketone)
- D: C6H5COC6H5 (Benzophenone)

### Step 3: Analyze Each Compound for Alpha Hydrogens

**Option A: C6H5CHO (Benzaldehyde)**
- Structure: C6H5-CHO
- Analysis: The carbonyl carbon (C=O) has no alpha hydrogens because the adjacent carbon is part of the phenyl group (C6H5).
- Conclusion: **Does not exhibit tautomerism.**

**Option B: C6H5C(=O)C(CH3)3 (A ketone with tert-butyl group)**
- Structure: C6H5-C(=O)-C(CH3)3
- Analysis: The carbonyl carbon is adjacent to a tert-butyl group, which has no alpha hydrogens.
- Conclusion: **Does not exhibit tautomerism.**

**Option C: C6H5COCH2COH (A diketone)**
- Structure: C6H5-CO-CH2-COH
- Analysis: This compound has two carbonyl groups. The CH2 group adjacent to the first carbonyl (C=O) has two alpha hydrogens.
- Conclusion: **Exhibits tautomerism.**

**Option D: C6H5COC6H5 (Benzophenone)**
- Structure: C6H5-CO-C6H5
- Analysis: The carbonyl carbon is adjacent to two phenyl groups, both of which do not have alpha hydrogens.
- Conclusion: **Does not exhibit tautomerism.**

### Step 4: Final Conclusion
Based on the analysis, the only compound that can exhibit tautomerism is **Option C: C6H5COCH2COH**.

### Summary of Results:
- Option A: No tautomerism
- Option B: No tautomerism
- Option C: Exhibits tautomerism
- Option D: No tautomerism