In previous publications we have shown that solvent effects on group frequencies can be studied conveniently by plotting the relative frequency shifts ∆ν/ν of one solute in a series of solvents, directly against the corresponding values for some other (Bellamy, Hallam & Williams 1958). Thus, ∆ν/ν the values for the NH stretching frequency of pyrrole yield a linear plot against the ∆ν/ν values for any other X—H stretching absorption such as the O—H of methanol or the B—H of decaborane. These relations hold over a wide range of different solvents, and each XH compound has a characteristic slope when plotted in this way against a common standard. The slopes measure the relative proton donating powers of the solutes. Similar plots have been obtained for a large number of carbonyl compounds (Bellamy & Williams 1958). Here the pattern of solvent effects is altogether different from that given by X—H links as the dipole available for solvent association is reversed. The sensitivity of individual carbonyl compounds to solvent effects varies widely and seems to depend upon a number of different factors.
No takes yet. Share an insight, caveat, or question.
Bellamy et al. (1960) studied this question.