Catalytic Transfer

Catalytic Transfer Hydrogenation

  • Catalytic hydrogenation is used for processing vegetable oils.

  • Hydrogenation process converts liquid vegetable oils into solids by saturating fats with hydrogen.

NMR Data Identification

  • Reliable process:

    • Determine functional group (chemical shift, IR data, etc.).

    • Draw isomers with the formula and functional group.

    • Predict and match NMR data to eliminate incorrect structures.

Chemistry of Fats and Oils

  • Saturated fats:

    • No alkenes, typically solids at room temperature.

  • Vegetable oils:

    • Contain alkenes, usually liquids at room temperature but can be solidified through hydrogenation.

Catalytic Transfer Hydrogenation Procedure

  • Steps include heating at reflux, filtration, purification, and characterization.

  • Reading assignments from Chapters 13 on techniques are required for lab preparation.

Alkenes and Bonding Theory

  • Ethylene has a pi bonding structure with delocalized electrons.

  • Pi bonds in alkenes undergo reduction via catalytic hydrogenation.

Mechanism of Catalytic Hydrogenation

  • Catalysts (e.g., Pd, Ni, or Pt) lower activation energy and perform the reaction without being consumed.

  • Reactions proceed primarily on the catalyst's surface (heterogeneous catalysis).

Result of Hydrogenation

  • Hydrogen is added to the same face of the alkene (syn addition).

  • If chirality is involved, one enantiomer may dominate (enantioselective catalysis).

Experiment Overview

  • Use 10% Pd/C as a catalyst with ammonium formate as a hydrogen source.

  • Monitor reaction progress via IR spectrum, comparing to literature for changes.

  • Procedures include careful filtration of catalyst and recrystallization of the final product.

In the experiment, the formate ion is used as a hydrogen source, specifically as part of ammonium formate, in conjunction with a 10% Pd/C catalyst for the catalytic transfer hydrogenation reaction.

Pd/C (Palladium on Carbon) is a heterogeneous catalyst, meaning the catalyst is in a different phase from the reactants. Structure-wise, it consists of very small, finely divided palladium metal particles (often nanoparticles) dispersed and supported on a high-surface-area activated carbon material. The carbon support provides a large surface for the palladium particles to be anchored, which increases the catalytic activity by making more palladium atoms available for the reaction and also helps to prevent the palladium particles from aggregating.