What kind of compounds undergo Cannizaro reactions ?

Options

A. Ketones with no c-hydrogen
B. Aldehydes with a- hydrogen
C. Carboxylic acids with a- hydrogen
D. Aldehydes with no a-hydrogen

Explanation

### Step-by-Step Solution:

1. **Understanding Cannizzaro Reaction**: The Cannizzaro reaction is a chemical reaction that involves the disproportionation of aldehydes in the presence of a strong base. In this reaction, one molecule of aldehyde is oxidized to a carboxylic acid, while another molecule is reduced to an alcohol.

2. **Identifying the Type of Aldehydes**: The key characteristic of the aldehydes that undergo the Cannizzaro reaction is that they must lack alpha hydrogen atoms. Alpha hydrogen atoms are the hydrogen atoms attached to the carbon atom adjacent to the carbonyl group (C=O).

3. **Examples of Aldehydes**: The most common example of an aldehyde that undergoes the Cannizzaro reaction is formaldehyde (HCHO), which has no alpha hydrogen. Other aldehydes that lack alpha hydrogen, such as benzaldehyde (C6H5CHO), also participate in this reaction.

4. **Reaction Conditions**: The Cannizzaro reaction requires a strong base, typically sodium hydroxide (NaOH), to facilitate the reaction.

5. **Products of the Reaction**: The products of the Cannizzaro reaction include:
- An oxidized product, which is a carboxylic acid (e.g., formic acid from formaldehyde).
- A reduced product, which is an alcohol (e.g., methanol from formaldehyde).

6. **Conclusion**: Therefore, the compounds that undergo the Cannizzaro reaction are aldehydes that do not have alpha hydrogen atoms.

### Final Answer:
The compounds that undergo Cannizzaro reactions are aldehydes that lack alpha hydrogen atoms.