DISCUSSION+greener+suzuki+reaction

The Greener Suzuki Reaction Hailey Baldwin


 * Introduction:** The Greener Suzuki reaction lab experiment highlights a famous method used to form new carbon-carbon bonding through the coupling of separate hydrocarbon pieces via a metal catalyst, as well as introduces certain adaptations that make the reaction more environmentally friendly. The changes from the traditional Suzuki reaction include using Palladium on carbon as the metal catalyst and water as the solvent. Organometallic reactions often incorporate organic solvent such as isopropanol since aqueous conditions tend to be unfavorable. However the Suzuki reaction excel when water is used as the solvent. Water is nonflammable, cheap and nonhazardous to human and the environment. During the Green Suzuki reaction experiment phenylboronic acid is coupled with the 4-iodophenol, using 10% Pd/C as the catalyst forming 4-phenylphenol, which is used as a non-steroidal anti-inflammatory drug.


 * The experiment in brief :** included working in the fumehood to combine Phenylboronic acid (122 mg); potassium carbonate (415 mg); 4-iodophenol (220 mg); and water (10.0 ml) into a 50mL round bottom flask. Approximately 1 ml of water was added to the vial of 10% palladium on carbon. After mixing the two solutions in the reaction flask heat vigorously using a sand bath. Reflux continued for 30 minutes. Then the flask was removed from the heat and cooled to room temperature. Next HCL was adding to the solution until acidification was achieved. Then the collected solid was dissolved in about 10 ml of methanol and the Pd/C was removed by gravity filtration. Once completed about 10 ml of distilled water was added to the crude product causing a solid to precipitate out. The product was heated again until it dissolved into solution and cool to room temperature. Next recrystalization was facilitated by an ice bath. Collection of the crystalized product was done via vacuum filtration (Hirsch funnel) and the product was left to dry until following lab period. Product was removed from funnel weighed and the melting point and IR spectrum were taken.


 * Our results**: The products purity was determined by taking melting point and IR spectrum data. The melting point corresponded to the actual melting point and the IR spectrum had a major peak at 3422.26 indicating an alcohol. However the peak was not a regular shape for an alcohol. A possible reason for the difference is the swoop could be the result of a scale manipulation. A peak at around 3100 was noted; it lacked prominence, but indicated an sp2 hybridized carbon-hydrogen bond.


 * We learned when** adding the HCL be sure to stir the crude product very well after each drop of HCL. The methodical addition of HCL is necessary because the product acts like a sponge and will give conflicting results on litmus paper. We also learned that while removing the Pd/C it is important to set up a double filter paper system, as the particles are so fine they could pass through a single piece of filter paper. Or filtrating a second or third time may also accomplish removal of the tiny particles. We would suggest adding one of these steps into the lab procedure. One other improvement to the procedure would be changing the directions for rapid stirring during heating. However the procedure calls for a sand bath as the heating element, which is not stir bar friendly.


 * This experiment is highly suitable** for a second-year organic chemistry course for several reasons. The organometallic cross-coupling reaction is done in a straightforward and efficient manner. The desired product of 4-iodophenol and the desired product can be achieved within a 2-hour lab session. In addition, students are introduced to the famous Suzuki reaction while becoming familiar with multiple greener chemistry principles. Exploring environmentally friendly methods that add to the carbon-carbon backbone helps students understand how these molecules are the starting block for many organic syntheses.

Aktoudianakis E. Chan E. Edward A. Jarosz I, Lee V. Mui L. Thatipamala S. Dicks. A, Initials. (2008). "greening up" the suzuki reaction. //Journal of Chemical Education//, //85//, 555-557.

Thank you, Hailey, for your comments. +10