A Spectroscopic Study of Hydrogen Bonding in Performic and Peracetic Acids

Abstract

The infrared spectra of concentrated performic and peracctic acids were measured in the rock-salt region. The most significant features are theO-Hstretching frequency a t 3310-3350 cm.-1 and the O H bending frequency a t 1450 cm.-1 which, for both peracids, remain essentially the same in the vapor state a s in the liquid or in solution in nonpolar solvents. This is attributed to i~~tramolecular hydrogen bonds resulting in particularly stable five-membered rings, 0 .Steric conditions in the percarboxylic group are favorable to such ring formation or chelatiotz. From the observed freqi~ency shifts the energy of these hydrogen bonds is estimated to be about 7 kcal. per mole. No evidence for unchelated molecules was found even in very dilute solutions of peracetic acid in nonpolar solvent nor in the vapor a t low pressure and moderate temperature. Tentative assignments of the other freqiiencies i n the spectra of the peracids are made by comparison with those of formic and acetic acids.The danger involved in handling these peracids in concentrated form is emphasized.

Synthesis of Concentrated 18O‐Labelled Hydrogen Peroxide and of 2H‐, 13C‐ and 18O‐Labelled Peroxyformic Acid

“…From two X-ray studies [2] [3] it appears that, in the crystalline state, two peroxycarboxylic acid molecules are held together by H-bonds. An earlier microwave investigation of peroxyacetic acid revealed that the conformation in the gaseous state is strongly influenced by an intramolecular H-bond [4].This observation is in accord with recent ab initio calculations [5] and the fact that peroxycarboxylic acids do not dimerize in the gaseous state unlike carboxylic acids [6]. With the exception of a deuteriated species [4], we know of no reports of the preparation of isotopically substituted species of peroxycarboxylic acids.…”

Notizen: Solid State Structure of N,N-Dibenzylhydroxylamine

“…Molecular orbital calculations generally predict two minima for the rotation about the N -O bond in hydroxylamines, and favour the trans confor mation by about 3 kJ/mol in energy [4c, d]. How ever, in some cases IR studies of H2NOH and its methyl derivatives give contadictary results as far as the conform ation is concerned [14].…”

Infrared Studies on Rotational Isomerism. VI. Normal-Coordinate Analysis of 2-Chloro-, 2-Bromo-, and 2-Cyanoethanol

“…This relationship even holds for the case of the percarboxylic acids (7,15). In fact the correlation is a fairly close one; but this must be fortuitous as the other OH force constants also are involved here.…”