Infrared spectra of aqueous sodium benzoates and salicylates in the carboxyl-stretching region: chelation in aqueous sodium salicylates

Abstract

Infrared spectra in the frequency region 1300-1760cm-' are reported for 41 substituted sodium benzoates and 10 substituted sodium salicylates in deuterium oxide solution, and for 9 substituted salicylic acids in chloroforn~ and carbon tetrachloride solutions. Carboxylate stretching frequencies of benzoates and salicylates correlate poorly with substituent constants, but the asymmetric frequencies of benzoates and salicylates correlate well with each other, and the asymmetric frequencies of benzoates correlate well with the asymmetric frequencies of the corresponding nitrobenzenes. It is suggested that, among substituted aromatic compounds, group vibrations which couple with the ring vibrations may correlate well with similar vibrations of other groups, but not with coupled vibrations of different symmetry, uncoupled vibrations, or substituent constants. Chelation in chloroform solutions of salicylic acid dimers can be detected by its influence on substituent effects, but infrared spectra provide no good evidence for chelation in aqueous sodium salicylates.

Terpolymer resin II: Synthesis, characterization, and ion‐exchange properties of 2,4‐dihydroxyacetophenone–dithiooxamide–formaldehyde terpolymers

“…This increasing order of e max values may be due to introduction of more and more chromophores (thio group) and auxochromes (phenolic À ÀOH group) in the repeated unit of the terpolymer resins. 21,23 This observation is in good agreement with the proposed most probable structures of these terpolymer resins.…”

Resin I: Synthesis, characterization, and ion‐exchange properties of terpolymer resins derived from 2,4‐dihydroxypropiophenone, biuret, and formaldehyde

“…26 The sharp band displayed at 1615-1640 cm 21 may be due to the stretching vibration of carbonyl group of both, ketonic as well as biuret moiety. 25,27 The presence of -NH-in biuret moiety may be ascribed to aromatic skeletal ring. 27 The bond obtained at 1374, 1273, and 815 cm 21 suggest the presence of methylene bridges 26 in the polymer chain.1, 2, 3, 4, 5-pentasubstitution of aromatic ring is recognized from the bonds appearing at 1273, 1163, 1085, 992, and 813 cm 21 , respectively.…”

“…The singlet signal appearing at 7.6 to 7.4 (d) ppm may be due imido proton of -CO-NH-CO-linkage. [24][25][26][27][29][30][31] Triplet signals appeared in the region 6.3 to 6.55 (d) ppm can be assigned to amino protons of -C-NH-CO-linkage. Intense signal appeared in the region 3.8 to 4.3 (d) ppm may be due to proton of methylenic bridges (CH 2 ) of polymer chain.…”

Structural environments of carboxyl groups in natural organic molecules from terrestrial systems. Part 1: Infrared spectroscopy

“…For example, resonance effects play a strong role in stabilizing the carboxylate anion in 2-and 4-nitrobenzoate, which exhibit higher m as values than 3-nitrobenzoate. Vibrational coupling between m as and ring vibrations may also affect the m as band positions, leading to a poor correlation between m as and acid pK a for substituted aromatic carboxylates (Dunn and McDonald, 1969). The energies of ring vibrations and the degree of coupling are largely dependent on the type of substitution (Dunn and McDonald, 1969).…”