Discussion+suzuki

Philip Deenik

Green Suzuki Synthesis of 4-Phenylphenol.

This reaction is another method for creating a new carbon carbon bond via a metal catalyst. The un-green Suzuki reaction is useful however does not use a Pd/C catalyst and doesn't use water as a solvent. The greener version uses water as a solvent and a Pd/C catalyst. Water is a great solvent as it is non toxic to the environment. This reaction produces 4-Phenylphenol as a product, which is a commonly used as an anti-inflammatory.
 * Introduction**

1) In a fume hood, place the following in a 50-ml round bottom flask: Phenylboronic acid (122 mg); potassium carbonate (415 mg); 4-iodophenol (220 mg); and water (10.0 ml) 2) Add about 1 ml of water to the vial of 10% palladium on carbon, this will create a suspension. Transfer the suspension to the reaction flask. 3) Heat the mixture vigorously under reflux for 30 minutes, using a sand bath as the heat source, stir the reaction often. A solid may precipitate. 4) Remove flask from the sand bath and allow cooling to room temperature. 5) Add aqueous HCL (2 M) to the filtrate until acidic to litmus paper. Stir very well after adding the HCL as the solid acts as a sponge and will 'soak up' the acid. Collect the crude product via vacuum filtration (Hirsch funnel) and wash with water (10 ml). 6) Dissolve the collected solid in about 10 ml of methanol (25 ml Erlenmeyer flask) and remove the Pd/C by gravity filtration (collect in 50 ml Erlenmeyer). 7) Add about 10 ml of distilled water to the crude product dissolved in methanol, this will cause a solid to precipitate out. Heat until entire product has dissolved into solution. Once dissolved, allow cooling to room temp and then place in an ice bath. 8) collect recrystalized product via vacuum filtration (Hirsch funnel) and dry very thoroughly (can be left until following lab period). Remove solid from the funnel, weigh and take the melting point and IR spectrum.
 * Experimental Procedure**

During the reflux portion the procedure calls for rapid stirring, however the sand baths are not stir bar friendly, this was circumnavigated by manual stirring. To save time while cooling after reflux wrap the reaction vessel in a wet paper towel to accelerate cooling. While adding the HCL be sure to mix extremely well after each drop, the product acts like a sponge and will give conflicting results on litmus paper. While removing the Pd/C it is wise to set up a double filter paper system, as the particles are so fine they can pass through a single piece of filter paper. This can also be over come by repeating the filtration process multiple times.
 * Notes on Procedure**

The product was tested by taking a melting point and an IR spectrum, there was a major peak in the 3100 region, which is indicative of an alcohol group, however it is of irregular shape. A reason for this could be the presence of two benzene rings, as an aromatic ring IR is in roughly the same region, which could interact with the alcohol peak.
 * Results**

This is a very suitable reaction for an organic chemistry lab. That said, it is not suitable for a large lab setting, the limiting factor is the amount of fumehoods. With two groups in the lab it was very relaxed and a good lab, with eight groups however, it would be uncomfortable and over crowded. The techniques used in this lab are extremely important, for a student to know as well as encouraging a student to think about green reactions.
 * Suitability**

Thanks for your comments. +10.