Spectroscopic Evidence for Hydrogen Bonds: Comparison of Proton-Attracting Properties of Liquids. II

Abstract

Forty-two different organic liquids are rated according to their proton-attracting power by comparing the strength of the hydrogen bonds which they form with heavy methyl alcohol. The classes of liquids studied are: aldehydes, ketones, esters, ethers and amines. The amount of perturbation which the different solvents cause in the OD vibrational band of the CH3OD is taken as a measure of the strength of the deuterium bridges formed with the CH3OD. The study is a continuation of a previous work in which twenty-six similar liquids were studied, and the results agree with those of the former study in showing that according to proton-attracting power the different classes are in the order: esters<aldehydes and ketones<ethers <amines. From the study it is possible to observe the effects of unsaturation, substitution, and other structural variations on the electron donor power of the O or N atom to which the OD group forms a bond. It is shown that the strength of the deuterium bonds formed with CH3OD bears a close relation to the basicities of the solvents, to their solubilities for other proton donor solutes, and to their reactivity with other compounds. There appears to be no correlation between the dipole moments of the solvents and the strengths of the bonds formed with the CH3OD.

Protonation of the Carbonyl Group: Ii. The Basicities of Substituted Benzaldehydes

“…The evidence of other workers (3,4) indicates that alkyl aryl ethers are considerably less basic than aromatic aldehydes and ketones. This difference should be even more pronounced where there is an electron-withdrawing forilly1 group para to the alkoxyl group as shown below:…”

Biological Membranes: The Physical Basis of Ion and Nonelectrolyte Selectivity

“…•NH(CHah) i and that dipole-dipole forces, resonance stabiliza tion, and dispersion forces all contribute to the bridge strength. Spectro scopic studies (e.g., 136,137) have shown that -COOH >-CONH2 > OH are the most effective donor groups, -NH2 being considerably weaker ; and that the approximate potency sequence for acceptors is…”

Acid-base reactions in benzene and other organic solvents: Behavior of bromphthalein magenta with different classes of organic bases

“…However, the general pattern of behavior of bromphthalein magenta and its salts can be interpreted satisfactorily from a consideration of the proton-affinity of the solvent, but not from a consideration of its dielectric constant. Gordy has pointed out that there is no correlation evident in the dipole moments of solvents and the strengths of the bonds formed with CH30D [79].…”

“…In studying the deuteron-attracting properties of liquids by infrared pec troscopy, Gordy and his collaborators [78,79] measured the shift of the OD band of heavy methyl alcohol, CHaOD, or heavy water, DzO. Benzene was used as r eference solvent for CHaOD or D zO.…”

“…From table 7, class D, i t is evident that this compound possesses a higher solvating capacity than the usual types of esters. It is therefore interesting to note that it causes a much larger shift in the OD band of CHaOD than oth er ester s [79]. Moreover, the e tel'S of phosphoric acid arc exceptionally good solvents for monofluoroclichlorometbane [0] .…”