Name the reagent which is used in the conversion of `-COCl` group into `-CHO` group.

Explanation

To convert a carbonyl chloride group (-COCl) into an aldehyde group (-CHO), we can use a specific reagent known as S2PD (which stands for sodium borohydride in the presence of a catalyst) along with BSO4 (barium sulfate). This process is known as the Rosenmund reduction.

### Step-by-Step Solution:

1. **Identify the Functional Groups**:
- Start with the carbonyl chloride group (-COCl) that you want to convert to an aldehyde (-CHO).

2. **Select the Reagent**:
...