Polarity and basicity of solvents. Part 3. A new infrared spectroscopic indicator of hydrogen-bonding basicity

Abstract

Shifts of the carbonyl stretching vibration of trichloroacetic acid are measured for a series of hydrogen-bonding solvents. A correction is made for non-hydrogen-bonding solvent effects by means of an ‘i.r. comparison method’ identical to the solvatochromic comparison method. The resulting carbonyl shift Δν(CO) is correlated with Δν(OH) of MeOH ⋯ B complexes. The correlation is family dependent (π bases, sulphides, and nitrogen and oxygen bases).