Reducing Ketones on Benzene Rings with H2, Pd/C, 45 psi

In summary, catalytic hydrogenation under pressure can reduce a ketone on a benzene ring to a hydrocarbon. However, it should be noted that a nitro group may also be reduced to an amine under the same conditions, and it may be more effective to use a different reduction method for converting an aromatic ketone to an alkane.
  • #1
smithrg8
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Is there anyway that a Ketone on a benzene ring could be reduced to a hydrocarbon with the use of H2, Pd/C, 45 psi ? I know that carbonyls on aromatic rings are able to be reduced to alcohols via this method but would be interested in if it is possible (more so then practical) to fully reduce to a hydrocarbon w/ the listed reagents. I did some searching and may have found some articles which stated that it may be possible with quite a long reaction period. If this method won't would any variations of it suffice? Suppose H2 Nickel or Raney? Maybe increase in psi or temp?

Thanks for the help guys!
 

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A ketone on a benzene ring will be reduced with catalytic hydrogenation under pressure. However, in reference to the title of this thread, I'd also point out that a nitro group will be reduced to an amine under the same reaction conditions. So instead of going from m-nitrophenone to 3-ethylnitrobenzene, you'd most likely get 3-ethylaniline as your product instead. (EDIT: it's also possible to reduce the benzene ring to a cyclohexane under exposure to these types of conditions. It's better to look into something like a Wolff-Kischner reduction or a Clemmensen reduction to get an aromatic ketone to an alkane.)
 

1. What is the purpose of reducing ketones on benzene rings?

The purpose of reducing ketones on benzene rings is to convert the ketone functional group into a more stable and reactive alcohol functional group. This allows for further chemical modifications and synthesis of more complex molecules.

2. What is the role of H2, Pd/C, and 45 psi in this reaction?

H2, Pd/C, and 45 psi are all components of the reducing agent used in this reaction. H2 is the source of hydrogen, Pd/C is the catalyst that facilitates the reduction, and 45 psi refers to the amount of pressure applied to the reaction vessel to ensure efficient conversion of the ketone.

3. How does the reduction of ketones on benzene rings differ from other reduction reactions?

The reduction of ketones on benzene rings typically requires more harsh conditions, such as high pressure and temperature, due to the stability of the benzene ring. This is in contrast to other reduction reactions which may only require mild conditions.

4. What are some potential side reactions that may occur during this reduction?

Some potential side reactions that may occur during this reduction include over-reduction to form alkanes, reduction of other functional groups present in the molecule, and formation of impurities due to the harsh reaction conditions.

5. Are there any safety precautions that should be taken when performing this reduction?

Yes, it is important to handle H2 gas with caution as it is flammable and can cause explosions if not properly handled. Appropriate protective gear, such as gloves and safety glasses, should also be worn when handling Pd/C and working with high pressures. It is also important to perform this reaction in a well-ventilated area to avoid the buildup of potentially hazardous gases.

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