Tunneling Control of Chemical Reactions: The Third Reactivity Paradigm

Abstract

This Perspective describes the emergence of tunneling control as a new reactivity paradigm in chemistry. The term denotes a tunneling reaction that passes through a high but narrow potential energy barrier, leading to formation of a product that would be disfavored if the reaction proceeded by passage over kinetic barriers rather than through them. This reactivity paradigm should be considered along with thermodynamic and kinetic control as a factor that can determine which of two or more possible products is likely to be the one obtained. Tunneling control is a concept that can provide a deep and detailed understanding of a variety of reactions that undergo facile (and possibly unrecognized) tunneling.

1,1‐Ethenediol: The Long Elusive Enol of Acetic Acid

“…In contrast to hydroxycarbenes, [49,50] quantum mechanical hydrogen tunnelling (QMT) of 1 ct to 3 t can be excluded, since we found no evidence for an increase in the bands of 3 t even after three days in the dark. The matrix spectrum of 1 ct remained unchanged because the associated barrier is simply too high and too wide to allow hydrogen tunneling.…”

Eyringpy: A program for computing rate constants in the gas phase and in solution

“…However, in some cases, it is mandatory to take into account other factors that can affect the accuracy of the computed rate constants. TST is intrinsically classical, thus inclusion of the quantum‐mechanical phenomena, like tunneling, is important for reactions that involve the transference of small mass particles or with narrow barriers, especially at low temperatures . Conversely, for reactions in solution, rate constants also depend on several aspects, such as the polarity and viscosity of the solvent in which the reaction is carried out.…”

Formation of Glyoxylic Acid in Interstellar Ices: A Key Entry Point for Prebiotic Chemistry

“…[7] DHF thermally bis-decarboxylates in aqueous solution to afford 4,w hich may further transform into higher aldoses. [9,10] Hydroxymethylene itself is able to react with 7 in abarrierless carbonyl-ene reaction to form 4 and this can further react to form 5,along with higher acyclic aldoses, thereby offering an uncatalyzed gas phase,b ase-free,s ugarforming reaction. [9,10] Hydroxymethylene itself is able to react with 7 in abarrierless carbonyl-ene reaction to form 4 and this can further react to form 5,along with higher acyclic aldoses, thereby offering an uncatalyzed gas phase,b ase-free,s ugarforming reaction.…”