Correct decreasing stability order of following carbanions :
`""^(Ө)underset(" "I)(CH_(2))-CHO" "CH_(3)-underset(O)underset(||)C-""^(Ө)CH-underset(II" ")underset(O)underset(||)C-CH_(3)" "H-underset(III)underset(O)underset(||)-overset(Ө)(CH)-underset(O)underset(||)C-H" "OHC-underset(IV)underset(CHO)underset(|)overset(Ө)C-CHO`

Options

A. `III gt IV gt II gt I`
B. `IV gt II gt III gt I`
C. `IV gt III gt II gt I`
D. `III gt II gt I gt IV`

Answer

To determine the correct decreasing stability order of the given carbanions, we will analyze each carbanion based on its structure and the effects of substituents on stability.

### Step-by-Step Solution:

1. **Identify the Type of Carbanion**:
- **Carbanion I**: `CH2-CHO`
- This carbanion has one carbon bonded to two hydrogens and one carbon. Thus, it is a **primary carbanion**.
- **Carbanion II**: `CH3-C(=O)-CH`
- This carbanion has one carbon bonded to one hydrogen and two carbons. Thus, it is a **secondary carbanion**.
- **Carbanion III**: `H-C(=O)-C-CHO`
- This carbanion has one carbon bonded to one hydrogen and two carbons. Thus, it is also a **secondary carbanion**.
- **Carbanion IV**: `OHC-C(=O)-CHO`
- This carbanion has one carbon bonded to three carbons. Thus, it is a **tertiary carbanion**.

2. **Determine Stability Based on Structure**:
- The general order of stability for carbanions is:
- Tertiary > Secondary > Primary
- However, we must also consider the effects of substituents (electron-donating vs. electron-withdrawing).

3. **Analyze the Effects of Substituents**:
- **Carbanion I** (Primary): Has one electron-withdrawing group (CHO), making it the least stable.
- **Carbanion II** (Secondary): Has one electron-donating group (CH3) and one electron-withdrawing group (C=O). The presence of CH3 makes it more stable than Carbanion I.
- **Carbanion III** (Secondary): Similar to Carbanion II but has two carbonyl groups (C=O), which are electron-withdrawing. This makes it less stable than Carbanion II.
- **Carbanion IV** (Tertiary): Has three electron-withdrawing groups (CHO), making it the most stable due to the stabilization provided by the electron-withdrawing nature of the groups.

4. **Rank the Carbanions**:
- Based on the analysis:
- Carbanion IV (most stable)
- Carbanion II (more stable than III)
- Carbanion III (less stable than II)
- Carbanion I (least stable)

5. **Final Order**:
- The correct decreasing order of stability is:
- **Carbanion IV > Carbanion II > Carbanion III > Carbanion I**
- Thus, the order is **4 > 2 > 3 > 1**.

### Final Answer:
The correct decreasing stability order of the carbanions is **4, 2, 3, 1**.