Chemistry. 2023 Jan 24. doi: 10.1002/chem.202203611. Online ahead of print.
ABSTRACT
For better understanding the intrinsic reactivity of organozinc reagents, we have examined the protolysis of the isolated zincate ions Et3Zn-, Et2Zn(OH)-, and Et2Zn(OH)2Li- by 2,2,2-trifluoroethanol in the gas phase. The protonation of the hydroxy groups and the release of water proceed much more efficiently than the protonation of the ethyl groups and the liberation of ethane. Quantum-chemical computations and statistical-rate theory calculations fully reproduce the experimental findings and attribute the lower reactivity of the more basic ethyl moiety to higher intrinsic barriers, which override the thermodynamic preference for its protonation. Thus, our minimalistic gas-phase model provides evidence for the intrinsically low reactivity of organozinc reagents toward proton donors and helps to explain their remarkable kinetic stability against moisture and even protic media.
PMID:36692992 | DOI:10.1002/chem.202203611
