Which of following statements is/are correct?

Options

A. In Reimer-Tiemann reaction, dichlorocarbene intermediate is produced.
B. Reimer-Tiemann reaction is example of electrophilic substitutions reaction.
C. Highly reactive ring like aniline & highly deactivated ring like nitrobenzene, cyanobenzene do not give Friedel Craft reaction
D. All of these

Answer

To determine which statements regarding the Riemer-Tiemann reaction and Friedel-Crafts reaction are correct, we will analyze each statement step by step.

### Step 1: Understanding the Riemer-Tiemann Reaction
The Riemer-Tiemann reaction involves the treatment of phenol with chloroform (CHCl3) in the presence of a base, typically sodium hydroxide (NaOH).

**Hint:** Recall that the Riemer-Tiemann reaction is a method to introduce an aldehyde group into the ortho or para position of phenol.

### Step 2: Formation of Dichlorocarbene
During the reaction, chloroform reacts with the base to generate dichlorocarbene (CCl2), which is a reactive intermediate.

**Hint:** Remember that dichlorocarbene is formed when a proton is abstracted from chloroform, leading to the loss of a water molecule.

### Step 3: Electrophilic Substitution Reaction
The Riemer-Tiemann reaction is classified as an electrophilic substitution reaction. The electron-donating -OH group on phenol increases the electron density at the ortho and para positions, making them more susceptible to electrophilic attack.

**Hint:** Identify the role of the -OH group in activating the aromatic ring for electrophilic substitution.

### Step 4: Analyzing the Statements
1. **Statement 1:** "In the Riemer-Tiemann reaction, dichlorocarbene intermediate is produced."
- This statement is **correct** as we have established that dichlorocarbene is indeed formed during the reaction.

2. **Statement 2:** "Riemer-Tiemann reaction is an example of electrophilic substitution reaction."
- This statement is also **correct** since the reaction involves the substitution of a hydrogen atom on the aromatic ring with an electrophile (dichlorocarbene).

3. **Statement 3:** "Highly reactive rings like aniline and highly deactivated rings like nitrobenzene and cyanobenzene do not give Friedel-Crafts reactions."
- This statement is **correct**. Aniline is too reactive and can form a positively charged intermediate in the presence of a Lewis acid, which destabilizes the reaction. Nitrobenzene and cyanobenzene are deactivated due to their electron-withdrawing groups, which reduce the electron density in the aromatic ring, making Friedel-Crafts reactions unfavorable.

### Step 5: Conclusion
Since all three statements are correct, the final conclusion is that **all of these statements are correct**.

**Final Answer:** All of the statements are correct.