Formyl chloride has not been prepared so far. Which of the following can function as formyl chloride in formylation?

Options

A. HCOOH + HCl
B. CO + HCl
C. `HCONH_(2)+HCl`
D. `HCOOCH_(3)+HCl`

Answer

To determine which of the given options can function as formyl chloride in formylation, we need to understand the concept of formylation and the role of formyl chloride in this process.

### Step-by-Step Solution:

1. **Understanding Formylation**:
Formylation is a chemical reaction that introduces a formyl group (-CHO) into a compound. Formyl chloride (HCOCl) is a reagent that can be used to achieve this.

2. **Analyzing the Options**:
We need to evaluate the options provided to see which can act as a source of formyl chloride. The question suggests that formyl chloride has not been prepared so far, so we need to look for alternatives.

3. **Option Evaluation**:
- **Option 1: HCOOH (Formic Acid)**:
- Formic acid is not a source of formyl chloride. It contains the formyl group but does not release HCl or CO, which are necessary for the generation of formyl chloride.
- **Conclusion**: Incorrect option.

- **Option 2: CO + HCl**:
- The combination of carbon monoxide (CO) and hydrogen chloride (HCl) can indeed produce formyl chloride (HCOCl) through the reaction:
\[ \text{CO} + \text{HCl} \rightarrow \text{HCOCl} \]
- **Conclusion**: Correct option.

4. **Final Answer**:
Based on the evaluations, the correct answer is that **CO + HCl** can function as formyl chloride in formylation.