Question

Draw the condensed structural formula of the organic product formed when each of the following is reduced by hydrogen in the presence of a nickel catalyst: a. butyraldehyde b. acetone c. hexanal

Short answer

a. CH3(CH2)2CH2OH, b. (CH3)2CHOH, c. CH3(CH2)4CH2OH.

Step-by-step solution

Understand the Reduction Reaction

Reduction of an aldehyde or ketone by hydrogen in the presence of a nickel catalyst converts the carbonyl group (C=O) into a hydroxyl group (C-OH), forming an alcohol.

Identify and Reduce Butyraldehyde

Butyraldehyde has the structure CH3(CH2)2CHO. Reducing the carbonyl group (CHO) yields butanol: CH3(CH2)2CH2OH.

Identify and Reduce Acetone

Acetone has the structure (CH3)2CO. Reducing the carbonyl group (CO) yields isopropanol: (CH3)2CHOH.

Identify and Reduce Hexanal

Hexanal has the structure CH3(CH2)4CHO. Reducing the carbonyl group (CHO) yields hexanol: CH3(CH2)4CH2OH.

Key concepts

Organic Chemistry

Organic chemistry is the branch of chemistry that studies the structure, properties, and reactions of organic compounds, which contain carbon atoms. The main elements involved, besides carbon, are hydrogen, oxygen, nitrogen, sulfur, and halogens.
Organic chemistry is central to all biological processes and many industrial applications, such as pharmaceuticals, petrochemicals, and food production.
The carbon atom's ability to form stable bonds with many elements, including itself, allows for a vast number of structural variations, leading to the rich diversity of organic compounds.

Hydrogenation Reaction

A hydrogenation reaction involves the addition of hydrogen (H2) to another compound, often facilitated by a catalyst. In organic chemistry, this reaction typically reduces or saturates organic compounds.
In the context of carbonyl compounds like aldehydes and ketones, hydrogenation requires a metal catalyst, such as nickel, to convert the carbonyl group (C=O) into a hydroxyl group (C-OH). This results in the formation of an alcohol.
The general reaction mechanism involves breaking the double bond of the carbonyl group and adding hydrogen atoms to the carbon and oxygen atoms.

• For aldehydes: R-CHO + H2 → R-CH2OH
• For ketones: R-CO-R' + H2 → R-CHOH-R'

This reaction is crucial in organic synthesis and industrial applications to create various alcohols used in everyday products and chemical processes.

Alcohol Formation

Alcohols are organic compounds with one or more hydroxyl groups (-OH) bound to a carbon atom. They are formed through various methods, including the reduction of aldehydes and ketones.
During the hydrogenation of aldehydes and ketones, the carbonyl group is reduced to a hydroxyl group. This transformation results in primary alcohols from aldehydes and secondary alcohols from ketones.

• From butyraldehyde (CH3(CH2)2CHO), reduction yields butanol (CH3(CH2)2CH2OH).
• From acetone ((CH3)2CO), reduction yields isopropanol ((CH3)2CHOH).
• From hexanal (CH3(CH2)4CHO), reduction yields hexanol (CH3(CH2)4CH2OH).

The presence of hydroxyl groups significantly influences the physical and chemical properties of alcohols, such as boiling points and solubility in water.

Aldehydes and Ketones

Aldehydes and ketones are organic compounds that contain a carbonyl group (C=O). They are essential in various chemical reactions and industrial applications.
Aldehydes have the carbonyl group at the end of the carbon chain, with the general formula R-CHO. They are typically more reactive than ketones. An example is butyraldehyde (CH3(CH2)2CHO).
Ketones have the carbonyl group within the carbon chain, with the general formula R-CO-R'. They are less reactive compared with aldehydes but are still crucial in organic chemistry. An example is acetone ((CH3)2CO).
Reduction of these carbonyl compounds by hydrogenation leads to the formation of alcohols, which is an important transformation in both laboratory and industrial processes.

• Butyraldehyde reduces to butanol.
• Acetone reduces to isopropanol.
• Hexanal reduces to hexanol.

Understanding the chemistry of aldehydes and ketones, together with their reactions, is fundamental to mastering organic synthesis.