Which of the following are electrophiles ?

Options

A. `BeCl_2`
B. `CH_2 = CH_2`
C. `HCl`
D. `BCl_3`

Answer

To determine which of the given species are electrophiles, we need to analyze each option based on the definition of electrophiles. Electrophiles are electron-deficient species that have a tendency to accept electrons. They can be positively charged or neutral and are often Lewis acids.

### Step-by-Step Solution:

1. **Identify the Options**: The options provided are:
- (A) BeCl2
- (B) CH2=CH2
- (C) HCl
- (D) BCl3

2. **Analyze Each Option**:
- **Option (A) BeCl2**:
- Beryllium chloride (BeCl2) is a Lewis acid and is electron-deficient because beryllium has only 2 valence electrons and forms bonds with 2 chlorine atoms, leaving it short of electrons. Thus, BeCl2 can accept electrons and is an electrophile.

- **Option (B) CH2=CH2**:
- Ethylene (CH2=CH2) is an alkene and is electron-rich due to the presence of a double bond. It does not have a tendency to accept electrons; instead, it can donate electrons. Therefore, CH2=CH2 is not an electrophile.

- **Option (C) HCl**:
- Hydrogen chloride (HCl) is also electron-deficient. Chlorine is highly electronegative and pulls electron density towards itself, making the hydrogen atom partially positive. Therefore, HCl can accept electrons and acts as an electrophile.

- **Option (D) BCl3**:
- Boron trichloride (BCl3) is another Lewis acid. Boron has 3 valence electrons and forms 3 bonds with chlorine atoms, but it still lacks 2 electrons to complete its octet. Thus, BCl3 is electron-deficient and can accept electrons, making it an electrophile.

3. **Conclusion**:
- The electrophiles among the options are:
- BeCl2 (Option A)
- HCl (Option C)
- BCl3 (Option D)

### Final Answer:
The electrophiles are **BeCl2, HCl, and BCl3** (Options A, C, and D).

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