Catalytic Hydrogenation Concepts and Challenges

The video tutorial explores enantioselective hydrogenation, focusing on breakthroughs by Knowles and Noyori. It discusses the outer shell mechanism, catalyst activation, and the reaction cycle. Applications of Noyori's technology, including dynamic kinetic resolution and imine hydrogenation, are highlighted. The tutorial emphasizes the stability and efficiency of these catalysts in synthesizing fine chemicals and pharmaceuticals.

What is the main advantage of Noyori's catalysts in enantioselective hydrogenation?

• They are inexpensive to produce.

• They achieve high levels of optical purity.

• They require no special conditions.

• They are used in all types of reactions.

In the outer shell mechanism, where does the substrate bind?

• To a free radical

• To the outer shell ligands

• To a solvent molecule

• Directly to the metal center

What is the role of the potassium amide moiety in the catalytic cycle?

• It increases the reaction temperature.

• It binds the substrate.

• It acts as a catalyst poison.

• It decomposes the catalyst.

How is stereoselectivity introduced in the catalytic cycle?

• By altering the pressure

• Through temperature control

• By using a chiral solvent

• Via diastereomeric transition states

What is the significance of the outer-shell mechanism in catalyst stability?

• It reduces the need for ligands.

• It prevents substrate binding to the metal center.

• It allows for higher reaction temperatures.

• It makes the catalyst more reactive.

What is a key feature of dynamic kinetic resolution?

• It uses a weak base to equilibrate enantiomers.

• It requires high temperatures.

• It is only applicable to olefins.

• It achieves 100% yield of a pure product.

What is a challenge in the enantioselective hydrogenation of imines?

• Imines require high pressure to react.

• Imines are not commercially available.

• Imines readily hydrolyze.

• Imines are too stable to react.

Which metal is used in the catalytic hydrogenation of metolachlor?

• Platinum

• Iridium

• Copper

• Gold

What is the turnover frequency (TOF) achieved in the hydrogenation of metolachlor?

• 300,000 molecules per hour

• 100,000 molecules per hour

• 200,000 molecules per hour

• 400,000 molecules per hour

What is the enantiomeric purity achieved in the hydrogenation of metolachlor?

• 70%

• 100%

• 80%

• 90%