An organic compound of molecular formula, `C_3H_6O` , forms 2,4 - dinitrophenylhydrazone, but gives negative Tollen's test . The compound is

Options

A. `CH_2=CH - CH_2-OH`
B. `CH_3CH_2CHO`
C. `CH_3COCH_3`
D. `CH_2=CH-OCH_3`

Answer

To solve the problem, we need to identify the organic compound with the molecular formula \( C_3H_6O \) that forms a 2,4-dinitrophenylhydrazone but gives a negative Tollen's test. Let's break down the steps:

### Step 1: Analyze the Molecular Formula
The molecular formula given is \( C_3H_6O \). This indicates that the compound contains three carbon atoms, six hydrogen atoms, and one oxygen atom.

**Hint:** Look for functional groups that could fit this molecular formula, particularly those that contain carbonyl groups.

### Step 2: Identify the Functional Group
The compound forms a 2,4-dinitrophenylhydrazone, which suggests that it contains a carbonyl group (C=O). Carbonyl groups are typically found in aldehydes and ketones.

**Hint:** Remember that both aldehydes and ketones can react with 2,4-DNP to form hydrazones.

### Step 3: Consider the Tollen's Test
The Tollen's test is used to differentiate between aldehydes and ketones. Aldehydes give a positive result (silver mirror), while ketones do not. Since the compound gives a negative Tollen's test, it cannot be an aldehyde.

**Hint:** Keep in mind that the negative result indicates that the compound is likely a ketone.

### Step 4: Determine the Structure
Given that the compound is a ketone with the molecular formula \( C_3H_6O \), we can deduce its structure. The simplest ketone with this formula is acetone, which has the structure \( CH_3COCH_3 \).

**Hint:** Visualize the structure of the compound to confirm it fits the ketone category.

### Step 5: Conclusion
The compound is acetone, which is a ketone that fits the criteria of forming a 2,4-dinitrophenylhydrazone and giving a negative Tollen's test.

**Final Answer:** The compound is acetone.

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