Case: Read the passage and answer the following questions

Alcohol can be prepared in many ways. Alcohols are prepared from alkenes by acid catalysed hydration and by hydroboration–oxidation. Alcohols are even prepared from ketones and aldehydes by reduction. The reduction of carboxylic acid and ester leads to the formation of alcohol. Alcohols are produced by the reaction of Grignard reagents with aldehydes and ketones. Phenol, also known as carbolic acid, was first isolated in the early nineteenth century from coal tar. Nowadays, phenol is commercially produced synthetically. In the laboratory, phenols are prepared from benzene derivatives in many ways.

What is the usual catalyst used in the reduction of aldehydes and ketones?

All of the above

The correct answer is option 4. All of the above.

Let us delve into the catalysts used in the reduction of aldehydes and ketones to alcohols, focusing on their characteristics and why they are used.

Reduction of Aldehydes and Ketones:
The reduction of aldehydes and ketones involves adding hydrogen \((H_2)\) to the carbonyl group \((C=O)\) to form the corresponding alcohol. This process is typically catalyzed by transition metals.

Catalysts Used:

1. Platinum (Pt):

Properties: Platinum is a noble metal with high catalytic activity and selectivity.

Application: It is often used in laboratory and industrial settings for hydrogenation reactions, including the reduction of aldehydes and ketones.

Conditions: Platinum catalysts can work under relatively mild conditions, making them suitable for sensitive compounds.

2. Palladium (Pd):

Properties: Palladium is another noble metal known for its high catalytic efficiency.

Application: Widely used in organic chemistry for various hydrogenation reactions, including the reduction of carbonyl compounds.

Conditions: Palladium catalysts are effective under a range of conditions and are often used in hydrogenation of aromatic compounds as well.

3. Nickel (Ni):

Properties: Nickel is less expensive compared to noble metals like platinum and palladium.

Application: Raney nickel, a common form of nickel catalyst, is highly porous and provides a large surface area for catalytic activity.

Conditions: Nickel catalysts typically require higher temperatures and pressures compared to platinum and palladium but are very effective for industrial-scale hydrogenations.

General Reduction Reaction:

The reduction of a carbonyl compound to an alcohol can be represented as:

Why All of the Above:

Versatility: All three metals (Pt, Pd, Ni) can facilitate the addition of hydrogen to the carbonyl group, reducing it to an alcohol.

Different Conditions: They may operate under different conditions (temperature, pressure), but all achieve the same end result.

Efficiency: Each has its own advantages, with platinum and palladium being more active and selective, while nickel offers cost-effectiveness for large-scale applications.

Conclusion: Since platinum, palladium, and nickel are all commonly used and effective catalysts for the reduction of aldehydes and ketones to alcohols, the correct answer is: All of the above.