100-year-old chemistry rule proven false, updating textbooks comes next

Ever heard of a rule that’s been around for so long, everyone just assumes it’s unbreakable? Well, a team of scientists is turning that notion on its head by proving wrong a key rule of organic chemistry.

Neil Garg, a distinguished professor of chemistry and biochemistry, is leading the charge to rewrite a fundamental principle that’s been part of organic chemistry for the past hundred years.

In a recent study published in Science, Garg and his colleagues at UCLA revealed that Bredt’s rule — a staple in chemistry textbooks since 1924 — might not be as ironclad as we’ve been led to believe.

But before we get into how they’re shaking things up, let’s take a step back and understand what this rule is all about.

What exactly is Bredt’s rule?

According to Bredt’s rule, you can’t have a double bond at the bridgehead position of a small, bridged ring system — a kind of molecular structure that looks like two rings sharing some atoms.

Imagine trying to fit a double bond in a tight space — it just doesn’t work because the molecule becomes too strained and unstable.

In these small ring systems, the atoms are connected in such a way that there’s not enough room for the flat shape of a double bond.

The angles get all messed up, and the molecule would be forced into an awkward position. It’s kind of like trying to bend a straight stick into a circle without breaking it — it just doesn’t work that way.

Bredt’s rule has been a guiding principle for chemists studying organic molecules, especially those known as olefins.

Olefins are compounds featuring a double bond between two carbon atoms, and they usually have a flat, planar structure.

Turning Bredt’s rule upside down

Garg’s team decided to challenge that assumption. Instead of accepting the limitations imposed by this long-standing rule, they set out to prove that these molecules, called anti-Bredt olefins (ABOs), can indeed be created and used.

“People aren’t exploring anti-Bredt olefins because they think they can’t,” Garg pointed out.

Using a clever approach, the researchers treated certain molecules known as silyl (pseudo)halides with a fluoride source. This reaction was designed to produce the elusive ABOs.

Since these molecules are highly unstable and tend to fall apart quickly, the team included another chemical to “trap” them.

This way, they could capture the ABOs long enough to study them and even use them to make new, valuable compounds.

Understanding anti-Bredt olefins (ABOs)

Anti-Bredt olefins are compounds that defy Bredt’s rule by featuring a double bond at the bridgehead position of a bridged ring system.

ABO’s challenge Bredt’s rule by simply existing, despite the inherent instability caused by this strain.

They provide valuable insights into the behavior of strained molecules and have potential applications in materials science and organic synthesis.

Why does this matter?

By showing that ABOs can be generated and utilized, the team is opening up new possibilities for drug discovery.

“There’s a big push in the pharmaceutical industry to develop chemical reactions that give three-dimensional structures like ours because they can be used to discover new medicines,” Garg explained.

The ability to create these unique molecular structures means scientists can explore a whole new realm of compounds that were previously off-limits.

More “rules” need to be challenged

Garg’s work doesn’t just break a rule — it invites the entire scientific community to rethink how we approach long-held beliefs.

“We shouldn’t have rules like this — or if we have them, they should only exist with the constant reminder that they’re guidelines, not rules. It destroys creativity when we have rules that supposedly can’t be overcome,” he said.

By challenging Bredt’s rule, the team is advocating for a more flexible and innovative approach to chemistry.

They’re reminding us that science is always evolving, and what we consider impossible today might just be tomorrow’s breakthrough.

Science needs more creativity

What does this mean for budding chemists and researchers?

It’s a call to question assumptions and push boundaries. If a century-old rule can be upended, who knows what other “impossible” feats are within reach?

“What this study shows is that contrary to one hundred years of conventional wisdom, chemists can make and use anti-Bredt olefins to make value-added products,” Garg noted.

It’s not just about breaking a rule; it’s about expanding the toolkit scientists have to tackle some of the world’s most pressing challenges, like developing new medications.

What’s next for Garg and Bredt’s rule?

This discovery is a stepping stone to numerous possibilities in organic chemistry, pharmaceuticals, and basically any other field of study.

By demonstrating that ABOs can be both generated and trapped effectively, Garg’s team has laid the groundwork for future research that could lead to significant advancements in medicine.

So, the next time you hear someone say, “You can’t do that,” remember that sometimes, all it takes is a fresh perspective and a willingness to challenge the status quo.

Who knows? You might just be the one to rewrite the next chapter in the science books.

The full study was published in the journal Science.

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