Which of the following is strongest nucleophile

Options

A. `Br^(-)`
B. `:OH^(-)`
C. `CN^(-)`
D. `C_(2)H_(5) barO:`

Answer

To determine the strongest nucleophile among the given options (Br⁻, OH⁻, CN⁻, and C₂H₅O⁻), we need to analyze the ability of each species to donate electrons. Here’s a step-by-step solution:

### Step 1: Understand the concept of nucleophilicity
A nucleophile is a species that donates an electron pair to form a chemical bond in a reaction. Stronger nucleophiles are typically less electronegative, as they can more readily donate their electrons.

**Hint:** Remember that nucleophiles are electron donors, and their strength is influenced by their electronegativity.

### Step 2: Analyze the first option (Br⁻)
Bromide ion (Br⁻) is a halogen. Halogens are generally electronegative, which means they tend to attract electrons rather than donate them. Therefore, Br⁻ is not a strong nucleophile.

**Hint:** Consider the electronegativity of halogens and how it affects their ability to donate electrons.

### Step 3: Analyze the second option (OH⁻)
The hydroxide ion (OH⁻) has a negative charge on oxygen. Oxygen is highly electronegative, which means it also tends to attract electrons. Thus, OH⁻ is not a strong nucleophile.

**Hint:** Recall that higher electronegativity in an atom usually leads to lower nucleophilicity.

### Step 4: Analyze the third option (CN⁻)
The cyanide ion (CN⁻) has a negative charge on carbon. Carbon is less electronegative compared to oxygen and halogens, which means it can more easily donate its electrons. Therefore, CN⁻ is a strong nucleophile.

**Hint:** Compare the electronegativity of carbon with that of oxygen and halogens to understand its nucleophilic strength.

### Step 5: Analyze the fourth option (C₂H₅O⁻)
The ethoxide ion (C₂H₅O⁻) has a negative charge on oxygen. Similar to OH⁻, oxygen's high electronegativity means it is not as willing to donate electrons, making C₂H₅O⁻ a weaker nucleophile compared to CN⁻.

**Hint:** Again, consider how the electronegativity of oxygen affects its ability to act as a nucleophile.

### Conclusion
After analyzing all the options, we can conclude that the strongest nucleophile among the given choices is **CN⁻**.

**Final Answer:** CN⁻ is the strongest nucleophile.