Question

These questions are referring to a Suzuki Cross Coupling Reaction. We turned phenylboronic acid to 1,1'-biphenyl-4-ol with p-iodophenol, K2Co3, Pd/C, H2O.

1. Pd/C is used as a catalyst in this reaction. Is this catalyst considered homogenous, or heterogeneous? Explain?

2. We call this reaction green. What does that term mean, and in which way can we say that the process is green? Explain briefly by using the exact conditions in this process, such as solvent, and catalyst.

3. Which reaction is finding place in step 15, upon addition of acid to the post-reaction mixture? Show the reaction schemes.

4. When we acquire the IR spectrum of the product in step 24, we use a nujol mull. Why do we not simply use dicholoromethane as is usually done with salt plate?

Answer 1

2) Answer :

Suzuki Coupling Reactions are those which use coupling partners such as a boronic acid and an organohalide catalyzed by a palladium complex
Note that this reaction si preferred mainly due to the availability of common boronic acids, mild reaction conditions, which are less toxic, by nature.
Boronic acids are less toxic and safer for the environment than organostannane and organozinc compounds. They are pretty easy to remove the inorganic by-products from reaction mixture. Therefore, this can be disosed easily.
The Suzuki cross-coupling reaction is a very efficient, reliable, and environmentally friendly method for the introduction of novel carboncarbon bonds into molecules. This review summarizes recent advances in the use of the reaction in aqueous media with a focus on different types of ligands and the ligandless protocols currently in use. Several synthetic targets for the reaction have been mentioned. The work summarizes recent results from studies on asymmetric Suzuki reactions performed in organic aqueous mixed solvents.Key words: Suzuki reaction, green chemistry, metal-catalyzed cross-coupling reactions, aqueous synthesis media.