Addition of alcohols to aldehydes in presence of anhydrous acids yield:

Options

A. Carboxylic acids
B. Ethers
C. Cyclic ethers
D. Acetals

Answer

To solve the question regarding the addition of alcohols to aldehydes in the presence of anhydrous acids, we can break down the process step by step:

### Step-by-Step Solution:

1. **Identify the Reactants**:
- We have an aldehyde (RCHO) and an alcohol (R'OH).
- The reaction takes place in the presence of an anhydrous acid, such as dry HCl.

2. **Protonation of the Aldehyde**:
- The lone pair of electrons on the oxygen of the aldehyde (RCHO) can attack a proton (H+) from the anhydrous acid.
- This leads to the formation of a protonated aldehyde (RCH(OH)⁺).

3. **Nucleophilic Attack by Alcohol**:
- The alcohol (R'OH) acts as a nucleophile and attacks the electrophilic carbon of the protonated aldehyde.
- This results in the formation of a tetrahedral intermediate (RCH(OH)(OR')).

4. **Formation of Acetal**:
- In the presence of an anhydrous acid, a water molecule is not formed. Instead, the hydroxyl group (OH) from the tetrahedral intermediate can be protonated and removed as water (H2O).
- This leads to the formation of an acetal (RCH(OR')(OR)).

5. **Final Product**:
- The final product of this reaction is an acetal, which is characterized by the structure RCH(OR')(OR).

### Conclusion:
The addition of alcohols to aldehydes in the presence of anhydrous acids yields **acetals**.