Question

Propose a structure for the product with formula \(\mathrm{C}_{9} \mathrm{H}_{17} \mathrm{~N}\) that results when 2 -(2-cyanoethyl)cyclohexanone is reduced catalytically.

Short answer

The product is a cyclohexanol with an ethylamine substituent.

Step-by-step solution

Identify the Reaction

The exercise involves the reduction of 2-(2-cyanoethyl)cyclohexanone. Catalytic reduction typically refers to hydrogenation, where hydrogen is added to multiple bonds such as double bonds or triple bonds, often with the help of a catalyst such as palladium on carbon (Pd/C).

Recognize Functional Groups

2-(2-cyanoethyl)cyclohexanone contains multiple functional groups: a cyano group (\(-C \equiv N\)) and a ketone group (cyclohexanone ring). Catalytic hydrogenation can reduce these groups.

Predict Reduction of the Ketone Group

The ketone group in the cyclohexanone can be reduced to an alcohol group. The process involves the addition of hydrogen to the carbonyl \((C=O)\) group, converting it to a secondary alcohol \((C-OH)\).

Predict Reduction of the Nitrile Group

The nitrile group (\(-C \equiv N\)) can be reduced to an amine group (\(-CH_2NH_2\)). The triple bond between carbon and nitrogen is broken, and hydrogen is added to both nitrogen and carbon.

Combine the Products: Alcohol and Amine

The structure arising from the reduction results in the conversion of the ketone to a cyclohexanol and the cyanoethyl chain to an ethylamine, maintaining the cyclohexane backbone.

Verify the Molecular Formula

After completing the reductions, the compound has a cyclohexyl group, an ethyl group converted to ethylamine, and the overall molecular formula should match \(\mathrm{C}_{9} \mathrm{H}_{17} \mathrm{~N}\). This confirms our structure.

Key concepts

Functional Groups

Functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. They play a significant role in organic chemistry by determining the properties and reactivity of compounds. In the case of 2-(2-cyanoethyl)cyclohexanone, the molecule possesses two notable functional groups:

• The cyano group \((-C \equiv N)\): This group is characterized by a triple bond between carbon and nitrogen, making it highly reactive in reductions.
• The ketone group: Found within the cyclohexanone ring, this group features a carbonyl bond \(C=O\), which is also a common target for reduction reactions.

Both of these functional groups can undergo catalytic hydrogenation, making them key areas of interest during the chemical modification process. Recognizing these groups is crucial before predicting the outcomes of reactions they participate in. Understanding how these groups transform under different conditions can simplify the prediction of reaction products, ultimately aiding in molecular design and synthesis.

Nitrile Reduction

Nitrile reduction is a process in which the cyano group \((-C \equiv N)\) is transformed into an amine \((-CH_2NH_2)\). Hydrogenation, or the addition of hydrogen, is commonly used to reduce nitriles. This reaction usually requires catalysts like palladium on carbon (Pd/C) to proceed effectively.During this reduction process:

• The triple bond between carbon and nitrogen in the nitrile group is broken.
• Hydrogen atoms are added to both the carbon and nitrogen, converting the nitrile into a primary amine.

In the context of our exercise, the 2-cyanoethyl group attached to the cyclohexanone undergoes this transformation. This change converts the cyano group into an ethylamine moiety, which drastically alters the molecule's functional profile and increases its potential reactivity with other compounds. Understanding nitrile reduction is fundamental when predicting how a molecule will function after undergoing catalytic hydrogenation.

Ketone Hydrogenation

Ketone hydrogenation is a reduction reaction where a ketone \(C=O\) is transformed into an alcohol \(C-OH\) by the addition of hydrogen. Catalytic hydrogenation typically involves the use of catalysts such as palladium on carbon (Pd/C) to facilitate the reaction.Here's what happens during ketone hydrogenation:

• Hydrogen molecules split and the atoms are added across the carbonyl bond.
• This breaks the double bond between carbon and oxygen, converting the carbonyl to an alcohol group.

In the exercise given, the cyclohexanone part of the molecule is reduced to cyclohexanol. As the ketone group is hydrogenated, we transition from a carbonyl-containing compound to one possessing a secondary alcohol, specifically a cyclohexanol. This change not only modifies the chemical and physical properties of the molecule but also affects its subsequent chemical behavior. Ketone hydrogenation showcases the versatility of catalytic hydrogenation in transforming functional groups, which is pivotal in synthetic organic chemistry.