Chemists find alkyl groups are electron-withdrawing, challenging a century-old belief

When is science settled? Are there any dogmas in science that stand the test of time? Ask his question again in thousand years from now! 😊

Electron, which direction? Both directions?

"Scientists are calling for changes to chemistry textbooks after discovering a fundamental aspect of structural organic chemistry has been incorrectly described for almost 100 years.

The team ... dispute the long-held belief that alkyl groups—a chemical group consisting of carbon and hydrogen atoms arranged in a chain—donate electrons to other parts of a molecule.

Instead, their research shows alkyl groups actually pull electrons away from the rest of the molecule, making them electron-withdrawing when compared to hydrogen ..."

"... Their findings, published in the journal Organic and Biomolecular Chemistry, overturn almost 100 years of dogma in the field of organic chemistry. ...

The distribution of electrons within molecules is central to chemistry and affects all aspects of chemical reactivity. ..."

From the abstract:

"It is commonly stated that alkyl groups exert an inductive electron-releasing effect when compared to hydrogen. This information has been given in numerous organic chemistry textbooks over the last 75 years. The evidence for this position is weak, and does not withstand scrutiny, and there is some evidence for the contrary position. We provide a significant body of computational data that clearly show that alkyl groups exert an inductive electron-withdrawing (–I) effect when compared to hydrogen. This revised position is not in conflict with experimental data, since alkyl group inductive effects are small and are likely to be masked by hyperconjugation/polarizability effects (particularly in charged species), and also by solvent effects. ..."

Chemists find alkyl groups are electron-withdrawing, challenging a century-old belief

Chemistry textbooks need rewriting after new research (original news release) "Scientists are calling for changes to chemistry textbooks after discovering a fundamental aspect of structural organic chemistry has been incorrectly described for almost 100 years."

Alkyl groups in organic molecules are NOT inductively electron-releasing (open access)

Fig. 4 Dipole moments in propane and isobutane.