Arrange the carbanions, `(CH_(3))_(3)bar(C),bar(C)Cl_(3),(CH_(3))_(2)bar(C)H,C_(6)H_(5)bar(C)H_(2)`, in order of their decreasing stability

Options

A. `C_(6)H_(5) overset(bar)CH_(2) gt overset(bar)(C)Cl_(3) gt (CH_(3))_(3) overset(bar)(C) gt (CH_(3))_(2) overset(bar)CH`
B. `(CH_(3))_(2) overset(bar)CH gt overset(bar)(C)Cl_(3) gt C_(6)H_(5) overset(bar)H_(2) gt (CH_(3))_(3) overset(bar)C`
C. `overset(bar)(C)Cl_(3) gt C_(6)H_(5) overset(bar)(C)H_(2) gt (CH_(3))_(2) overset(bar)(C)H gt (CH_(3))_(3) overset(bar)C`
D. `(CH_(3))_(3) overset(bar)C gt (CH_(3))_(2) overset(bar)(C)H gt C_(6)H_(5) overset(bar)(C)H_(2) gt overset(bar)(C)Cl_(3)`

Answer

To determine the stability of the given carbanions, we need to analyze the effects of substituents attached to the carbon atom bearing the negative charge. The stability of carbanions is influenced by the presence of electron-withdrawing groups (EWGs) and electron-donating groups (EDGs).

### Step-by-Step Solution:

1. **Identify the Carbanions:**
The carbanions given are:
- A: \((CH_3)_3C^-\) (tert-butyl anion)
- B: \(CCl_3^-\) (trichloromethyl anion)
- C: \((CH_3)_2C^-\) (isopropyl anion)
- D: \(C_6H_5CH_2^-\) (benzyl anion)

2. **Analyze Electron-Donating and Electron-Withdrawing Effects:**
- **A: \((CH_3)_3C^-\)**: The three methyl groups are electron-donating (+I effect), which destabilizes the carbanion by increasing electron density on the negatively charged carbon.
- **B: \(CCl_3^-\)**: The three chlorine atoms are strong electron-withdrawing groups (-I effect), which stabilize the carbanion by pulling electron density away from the negatively charged carbon.
- **C: \((CH_3)_2C^-\)**: The two methyl groups also exert a +I effect, but less than in A, making this carbanion less destabilized than A but still less stable than B.
- **D: \(C_6H_5CH_2^-\)**: The negative charge on the carbon can be stabilized by resonance with the phenyl ring. This resonance effect significantly stabilizes the carbanion.

3. **Rank the Carbanions Based on Stability:**
- **Most Stable**: D (\(C_6H_5CH_2^-\)) - due to resonance stabilization.
- **Next Stable**: B (\(CCl_3^-\)) - due to strong -I effect from three chlorine atoms.
- **Less Stable**: C (\((CH_3)_2C^-\)) - less destabilized by two +I groups.
- **Least Stable**: A (\((CH_3)_3C^-\)) - most destabilized by three +I groups.

4. **Final Order of Stability:**
The order of stability from most stable to least stable is:
\[ C_6H_5CH_2^- > CCl_3^- > (CH_3)_2C^- > (CH_3)_3C^- \]

### Final Answer:
The stability order of the carbanions is:
\[ C_6H_5CH_2^- > CCl_3^- > (CH_3)_2C^- > (CH_3)_3C^- \]