A carbonyl compound gives a positive iodoform test but does not refuce tollen's reagent or Fehling's solution. If forms a cyanohydrin with HCN, which on hydrolysis gives a hydroxy acld with a methyl side chain. Compound is :

Options

A. Acetaldehyde
B. Propionaldehyde
C. Acetone
D. Crotonaldehyde

Answer

To solve the problem, we need to analyze the information given about the carbonyl compound step by step.

### Step 1: Identify the characteristics of the compound
The compound gives a positive iodoform test, which indicates that it must have a methyl ketone structure (i.e., a carbonyl group adjacent to a methyl group). However, it does not reduce Tollens' reagent or Fehling's solution, suggesting that it is not an aldehyde.

**Hint:** Recall that the iodoform test is specific for methyl ketones and some secondary alcohols, while Tollens' and Fehling's tests are used to identify aldehydes.

### Step 2: Determine the type of carbonyl compound
Since the compound does not reduce Tollens' reagent or Fehling's solution, it must be a ketone. Aldehydes would give a positive result for these tests. Therefore, we can conclude that the compound is a ketone.

**Hint:** Remember that only aldehydes can reduce Tollens' and Fehling's reagents, while ketones do not.

### Step 3: Analyze the formation of cyanohydrin
The compound forms a cyanohydrin with HCN. This means that the carbonyl carbon is reactive towards nucleophiles, and the addition of HCN leads to the formation of a cyanohydrin. The presence of a cyanohydrin indicates that the carbonyl compound is likely to have a structure that allows for this reaction.

**Hint:** A cyanohydrin is formed when HCN adds to a carbonyl group, resulting in a compound containing both -CN and -OH groups.

### Step 4: Hydrolysis of the cyanohydrin
Upon hydrolysis, the cyanohydrin will convert to a hydroxy acid. The problem states that this hydroxy acid has a methyl side chain, which means that the original ketone must also have a methyl group in its structure.

**Hint:** Hydrolysis of a cyanohydrin replaces the -CN group with a -COOH group, forming a carboxylic acid.

### Step 5: Identify the possible compounds
Now we need to analyze the options given:
1. Acetaldehyde (an aldehyde, so it cannot be the answer)
2. Propionaldehyde (also an aldehyde, so it cannot be the answer)
3. Acetone (a ketone, CH3COCH3)
4. Crotonaldehyde (an aldehyde, so it cannot be the answer)

Among these, only acetone is a ketone that can give a positive iodoform test and does not reduce Tollens' or Fehling's reagents.

**Hint:** Look for the compound that matches the criteria of being a ketone with a methyl group adjacent to the carbonyl.

### Conclusion
The compound that fits all the criteria given in the question is **Acetone (CH3COCH3)**.

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