A 19F Solvatomagnetic Comparison Method for the Determination of the α1 Scale of Solvent Hydrogen‐Bond Donation and Its Application to Deep Eutectic Solvents.

ABSTRACT We develop a nonsolvatochromic comparison method for the determination of the <italic>α</italic>1 scale of solvent hydrogen‐bond acidity by means of 19F NMR spectrometry. We compare the 19F chemical shifts of 4‐fluoro‐2‐methylpyridine (as a sensitive hydrogen‐bond acceptor probe) and of 4‐fluoronitrobenzene (as a chemically similar but less basic reference probe). This so‐called 19F solvatomagnetic comparison method yields the hydrogen‐bonding contribution to <italic>δ</italic> (19F)(4‐fluoro‐2‐methylpyridine) that is well correlated to <italic>α</italic>1 values obtained from the solvatochromism of Reichardt's betaine dye. Therefore, this solvatomagnetic comparison method is applied to determine the <italic>α</italic>1 values of 13 choline chloride–based deep eutectic solvents. [ABSTRACT FROM AUTHOR]