Intramolecular Hydrogen Bonds. XII. The Dipolar-field and the Hydrogen-bonding Effects of the Hydroxyl Group on the Carbonyl Frequencies of Aliphatic Hydroxy-carboxylates

Abstract The infrared carbonyl-stretching absorption bands of several methoxy- and hydroxyalkanoates have been measured in dilute carbon tetrachloride solutions, and their frequency shifts from the normal bands of ethyl alkanoates have been explained in terms of the dipolar-field and the hydrogen-bonding effects of the substituents. Further, as regards the direction of hydrogen bonding, the spectral data of the hydroxy-esters lead to essentially the same conclusion as that based on their hydroxyl spectra. However, the magnitudes of the carbonyl-frequency shifts due to hydrogen bonding can not be related to those of the corresponding hydroxyl shifts.