120-Year-Old Grignard Reaction Finally Solved

When it comes to equations related to making new molecules, none is more important or more complex than the Grignard reaction. The reaction is used to synthesize carbon-carbon bonds.

More than 100 years

However, finding low-cost materials and minimal energy resources for this reaction has been the focus of more than 100 years. That is because the exact way that the Grignard reaction actually works has been unknown.

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Now, all of this may change, as a breakthrough has been made to help us understand the way the Grignard reaction works, reported by Phys.Org. As we finally come to grips with it, we may potentially discover ways to improve it.

It was 120 years ago that the Grignard reaction allowed the tailored formation of carbon-carbon bonds for the first time - a reaction that since then has been studied, but never fully understood.

Five years ago, Professor Odile Eisenstein and Professor Michele Cascella decided to have a closer look and tackle the problem using computer simulations.

Modeling both the reagent and the solvent, they were able to detect the multiple chemical species during the Schlenk equilibrium. They discovered that the whole process is determined by solvent molecules that combine to, or detach from, the magnesium atoms.

Uncovering that the Grignard reagent is not a single well-defined compound, rather an ever-changing dancer, it now became possible to look at the reaction. 

Not restricted by physical reality

"One of the advantages of a computational study is that you are not restricted by the physical reality, you can systematically test multiple hypotheses, and determine which is the best only a posteriori," told Phys.Org Cascella.

Through using computer simulations accompanied by high-level quantum chemistry data, it was possible to establish a series of key points. "What has always been known as the Grignard reaction is, in reality, a group of reactions that occur simultaneously in the same sample," explained Cascella.

And this is just the start over their work.

"We have just scratched the surface," said Eisenstein. "It has long been known that the organometallic reactions can be enhanced with a large variety of additives, such as salts, derivatives of other metal compounds, etc. Additives can make a reaction faster and cleaner. However, nobody really knows how they work. Now that we have a sufficient understanding of the Grignard reaction, we can construct from this. Once we know how to bake a cake, we can make it tastier and more beautiful. In other words, we can understand the role of additives, and hopefully, propose new ones."