What is the electrophile when RCl + `AlCl_3` are used in Friedel-Crafts reaction ?

Options

A. `Cl^+`
B. `AlCl_4^-`
C. `R^+`
D. `AlCl_2^+`

Answer

To determine the electrophile in the Friedel-Crafts reaction involving RCl and AlCl3, we can follow these steps:

### Step 1: Understand the Reaction Components
In the Friedel-Crafts reaction, we are using RCl (an alkyl chloride) and AlCl3 (aluminum chloride).

### Step 2: Identify the Role of AlCl3
AlCl3 acts as a Lewis acid in this reaction. It has a strong tendency to accept electrons due to its electron-deficient nature. When AlCl3 interacts with RCl, it forms a complex.

### Step 3: Formation of the Electrophile
When RCl reacts with AlCl3, the aluminum chloride coordinates with the chlorine atom of RCl. This results in the formation of a carbocation (R+) and a complex ion (AlCl4-). The reaction can be represented as follows:

\[ RCl + AlCl_3 \rightarrow R^+ + AlCl_4^- \]

### Step 4: Identify the Electrophile
In this reaction, the species R+ (the carbocation) is positively charged and is electron-deficient. Therefore, it acts as the electrophile in the Friedel-Crafts reaction.

### Conclusion
The electrophile formed when RCl and AlCl3 are used in the Friedel-Crafts reaction is R+.

### Final Answer
The electrophile is R+.

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