Self-Association of Acetic Acid in Dilute Deuterated Chloroform. Wide-Range Spectral Reconstructions and Analysis using FTIR Spectroscopy, BTEM, and DFT

Abstract

The binary solution of acetic acid in CDCl(3) was studied at room pressure on the interval T = 293-313 K with a series of acetic acid concentrations up to 0.16 M. In-situ Fourier transform infrared (FTIR) spectroscopy measurements on the interval of 400-3800 cm(-1) were utilized as the analytical method to monitor the spectral changes due to self-association of acetic acid. The band-target entropy minimization (BTEM) algorithm was employed to reconstruct the underlying pure component spectra. Analysis successfully provided two major spectral estimates of acetic acid, namely, the monomer (primarily in the form of monomer-CDCl(3) complex) and the centrosymmetric cyclic dimer. In addition, analysis provided one minor spectral estimate containing signals from both noncyclic dimers and higher aggregates. Also, spectral estimates were obtained for phosgene and water which were present at trace levels even though considerable precaution was taken to conduct the experiments under anhydrous and anaerobic conditions. Density functional theory (DFT) calculation was performed to assign the acetic acid structures corresponding to the BTEM spectral estimates. Since the structure of dilute acetic acid has been the subject of numerous studies, the present investigation helps to resolve some issues concerning the speciation of acetic acid at low concentrations in low polarity solvents. In particular, the present study provides for the first time, wide-range spectral reconstructions of the species present.

Hydrogen-bonded clusters of 1, 1′-ferrocenedicarboxylic acid on Au(111) are initially formed in solution

“…However, the experimental conditions were quite different from those employed during our deposition, and it is reasonable to expect that neutral clusters of hydrogen bonding molecules can form in the aerosol droplets as has been observed in simpler molecular systems. [43][44][45] The hexamers need not be a majority species, and the presence of metastable molecular clusters is possible in the non-equilibrium conditions that can exist in a aerosol droplet undergoing evaporation 35,36 or a thin evaporating film of solvent. 37 Once these metastable species form, they come out of solution as predicted by Ostwald's rule, which states that less-stable species will precipitate out of solution prior to more-stable structures.…”

Regioselective Orthopalladation of (Z)-2-Aryl-4-Arylidene-5(4H)-Oxazolones: Scope, Kinetico-Mechanistic, and Density Functional Theory Studies of the C–H Bond Activation

“…Surprisingly, though, all the PdÀO (coordinated carboxylate) calculated distances are the same within error, indicating that the hydrogen bonding interactions are capable of compensating for the lower Lewis basicity of the ligands (translated into lower MÀL bond strength and longer MÀL distances), possibly because of the formation of rather stable Pd-OC(R)OH-O-cycles. 34 It is clear that the assumption of a continuous model for the solvent for systems prone to hydrogen bonding has to be considered very carefully; in these systems hydrogen bonding networks play a crucial role.…”

Hydrogen-bonded clusters of ferrocenecarboxylic acid on Au(111)

“…There is some experimental evidence that other carboxylic acids form trimers or larger clusters in solution. 21,22 The pulse-deposition process used to deposit FcCOOH on the surface involves rapid drying of solvent, as the sample is exposed to microliter-sized droplets of solution that are released into vacuum via half-millisecond pulses of a solenoid valve. This likely creates conditions of concentration and temperature that are not accessible through other deposition methods.…”