Which of the following reactions does not involve reduction

Options

A. `R-COOH to RCH_2OH`
B. `RCHO to RCH_2OH`
C. `R-CO-R' to R-CH_2-R'`
D. `R-underset(OH)underset(|)CH-R'to R-underset(O)underset(||)C-R'`

Answer

To determine which of the given reactions does not involve reduction, we first need to understand what reduction means in the context of organic chemistry. Reduction generally refers to the process of gaining electrons, which can be interpreted as the addition of hydrogen or the removal of oxygen.

### Step-by-Step Solution:

1. **Understanding Reduction**:
- Reduction involves either the addition of hydrogen or the removal of oxygen from a compound.
- Common examples include the conversion of carbonyl compounds (like aldehydes and ketones) to alcohols.

2. **Analyzing the Options**:
- We will evaluate each option to see if it involves reduction.

3. **Option A**:
- **Reaction**: Acid to Alcohol
- **Analysis**: This is a reduction process because the carboxylic acid (which contains a carbonyl group) is being converted to an alcohol, indicating the addition of hydrogen and the removal of oxygen.

4. **Option B**:
- **Reaction**: Aldehyde to Alcohol
- **Analysis**: This is also a reduction process as aldehydes are converted to alcohols, again indicating the addition of hydrogen and the removal of oxygen.

5. **Option C**:
- **Reaction**: RCO group to RCH2R
- **Analysis**: This reaction involves the reduction of a carbonyl group (C=O) to an alcohol (C-H), which means that oxygen is being removed and hydrogen is being added, thus it is a reduction.

6. **Option D**:
- **Reaction**: Alcohol to Ketone
- **Analysis**: This reaction involves the oxidation of an alcohol to a ketone. In this case, there is a loss of hydrogen and/or the addition of oxygen, which does not qualify as reduction.

7. **Conclusion**:
- The reaction that does not involve reduction is **Option D** (Alcohol to Ketone).

### Final Answer:
**Option D** does not involve reduction.