The Strong β−CF₃ Shielding Effect in Hexafluoroisopropanol and 100 Other Organic Solvents Revisited with ¹⁷O NMR Spectroscopy

Abstract

An 17O NMR spectroscopy survey of more than 100 ubiquitous organic solvents and compounds, including some typical oxofluorinated solvents such as hexafluoroisopropanol, trifluoroethanol, trifluoroacetic acid, and others, is presented with D2O as a reference. A strong alternating α,β−CF3‐substituent chemical shift effect was thus observed. This alternating deshielding–shielding effect is suspected to have a role in the exceptional properties of these oxofluorinated solvents, notably in oxidative cross‐coupling reactions.

Carboxylate-directed C–H allylation with allyl alcohols or ethers

“…The solvent turned out to be the critical parameter. 21 Aprotic solvents (toluene or CH 3 CN) gave low yields and insufficient selectivity for the desired allylarene 3aa over the β-H elimination by-product 3aa′ (entries 1 and 2). In protic solvents, in contrast, the reaction was highly selective for the desired product 3aa .…”

Emerging unconventional organic solvents for C–H bond and related functionalization reactions

“…[2][3][4] Interestingly, this is also associated with a very strong shielding effect at the oxygen atom, easily measured in 17 O NMR spectroscopy, in comparison to the non-fluorinated analogues (Scheme 1). 5 All these properties ensure highly specific solvation of transitions states, typically decreasing activation energies.…”

Insight and performance of LC‐DFT vs DFT in the NMR shielding and chemical shift calculations: Case of CHClCHCF3

“…Nuclear magnetic resonance spectroscopy (NMR) has become a powerful tool for obtaining information concerning the structure and dynamics of molecules. [ 1–37 ] In the field of molecular modeling, the assessment of the NMR shielding was addressed by Ramsey in the early 1950s. [ 5,9 ] Thereafter, it has been modernized by Stevens et al in 1963.…”