Which statement about formaldehyde is correct

Options

A. It undergoes oxidation reaction with Tollen's reagent
B. It underegoes disproportination reaction with dil. NaOH
C. It undergoes electrophilic substitution reaction with phenol
D. It undergoes nucleophilic addition reaction with Grignard reagent

Explanation

To determine which statements about formaldehyde are correct, we will analyze each statement one by one.

### Step 1: Analyze the first statement
**Statement:** Formaldehyde undergoes oxidation reaction with Tollens reagent.

**Solution:**
Formaldehyde (HCHO) does indeed undergo oxidation when treated with Tollens reagent (Ag(NH3)2^+). The reaction results in the formation of a carboxylic acid (formic acid, HCOOH) or its carboxylate ion (HCOO^-). Thus, this statement is correct.

### Step 2: Analyze the second statement
**Statement:** Formaldehyde undergoes disproportionation reaction with dilute NaOH.

**Solution:**
Formaldehyde can undergo a disproportionation reaction known as the Cannizzaro reaction, where it does not have any alpha hydrogen. In this reaction, one molecule of formaldehyde is oxidized to formate ion (HCOO^-) and another molecule is reduced to methanol (CH3OH). Therefore, this statement is also correct.

### Step 3: Analyze the third statement
**Statement:** Formaldehyde undergoes electrophilic substitution reaction with phenol.

**Solution:**
When formaldehyde reacts with phenol in an acidic medium, it undergoes an electrophilic substitution reaction. The hydroxyl group of phenol directs the substitution to the ortho and para positions, resulting in the formation of ortho- and para-hydroxybenzyl alcohols. Thus, this statement is correct.

### Step 4: Analyze the fourth statement
**Statement:** Formaldehyde undergoes nucleophilic addition reaction with Grignard reagent.

**Solution:**
Formaldehyde reacts with Grignard reagents (RMgX) to form primary alcohols. The nucleophilic carbon in the Grignard reagent attacks the electrophilic carbon in formaldehyde, leading to the formation of a primary alcohol after hydrolysis. Therefore, this statement is also correct.

### Conclusion
All statements regarding formaldehyde are correct. Thus, the answer is that statements A, B, C, and D are all correct.

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