Etude structurale des associationsde l'acide acetique en solution par spectroscopie infrarouge et calculs quantiques C.N.D.O./2

Dervil, E.; Odiot, S.

doi:10.1016/0022-2860(79)80274-4

Cited by 7 publications

(12 citation statements)

References 15 publications

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“…As for the shoulder, the interpretation given in the literature is that solvated forms may have several conformers. 26 Be that as it may, the interaction between pivalic acid and the solvent appears strong enough to completely eliminate the signal of dimerized species in DME.…”

Section: ■ Resultsmentioning

confidence: 96%

“…Obviously, this band corresponds to the solvated species OC–O–H···O where the hydroxyl is H-bounded to an oxygen atom of the solvent, but the carbonyl vibrates freely. As for the shoulder, the interpretation given in the literature is that solvated forms may have several conformers . Be that as it may, the interaction between pivalic acid and the solvent appears strong enough to completely eliminate the signal of dimerized species in DME.…”

Section: Resultsmentioning

confidence: 99%

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Polymethacrylic Acid Shows Thermoresponsivity in an Organic Solvent

et al. 2019

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The alternating sequenced copolymer poly-(methacrylic acid-alt-hydroxyethyl acrylate), p(MAA-alt-HEA), was recently found to display a lower critical solution temperature (LCST) behavior in 1,2-dimethoxyethane (DME), whereas the random copolymer of the same average molecular weight and composition did not. As an effort to understand this peculiar behavior, we investigated solutions of both corresponding homopolymers, poly(methacrylic acid) (pMAA) and poly(2-hydroxyethyl acrylate) (pHEA), in DME. We found that in the same temperature range, concentration, and degree of polymerization, pHEA is fully soluble, whereas pMAA shows the LCST behavior similar to the alternating copolymer. On the basis of Hansen’s parameters of the homopolymers, it would be predicted that neither should dissolve in DME. Solubility is therefore connected to specific solvent–polymer interactions and more specifically to the formation of a polymer–solvent complex via hydrogen bonds. We designed a method which combines mid-infrared (MIR) and near-infrared (NIR) spectroscopy in solution to study hydrogen bonding as a function of temperature (by MIR) with simultaneous monitoring of LCST (by NIR). In parallel, the global shape of polymer chains and aggregates was characterized by small-angle neutron scattering in deuterated DME. It is found that pMAA chains form aggregates upon increase of temperature through formation of cyclic H-bonded dicarboxylic dimers. As for pHEA, the solvent’s quality of DME slightly decreases with temperature, but aggregation is prevented by entropic repulsion of the flexible side chains. We thus concluded that nonoccurrence of LCST in the random copolymer is due to the presence of pHEA homoblocks that maintain constant solubility over the whole temperature range.

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Section: ■ Resultsmentioning

confidence: 96%

Section: Resultsmentioning

confidence: 99%

Polymethacrylic Acid Shows Thermoresponsivity in an Organic Solvent

et al. 2019

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“…Other species such as higher multimers, open dimers, and eis and trans monomers have also been considered in studies on carboxylic acids [5,9,12]. It turned out that the cyclic dimer is the dominant associated species in both, the gaseous and liquid phase.…”

Section: Discussionmentioning

confidence: 99%

“…A large body of literature has accumulated on the carboxylic acid association [4][5][6][7][8][9][10][11][12] with an excellent survey being provided in [13]. The hydrogenbonded system has been studied in various solvents as a function of temperature and concentration.…”

Section: Introductionmentioning

confidence: 99%

Dimerization of Carboxylic Acids in Solution up to High Pressures and Temperatures. 1. Pivalic Acid

Borschel

Buback

1987

Zeitschrift Für Naturforschung A

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Pivalic acid in dilute solution of n-heptane and of CC1 4 is studied via IR spectroscopy in the region of the C=0 and O-H stretching fundamentals up to pressures of 2 kbar and temperatures of 175 °C. Lambert-Beer's law is shown to be valid for the C = 0 modes of the acid monomer and of the hydrogen-bonded cyclic dimer, which enables the quantitative measurement of the dimerization equilibrium as a function of pressure and temperature. Increasing pressure favours the dimerization in n-heptane to a larger extent than in CC1 4 solution. In both solvents this pressure effect increases with temperature. The hydrogen bond strength within the dimer species is slightly reduced toward high pressure. The data on the temperature dependence of the dimerization volume and on the pressure dependence of the dimerization enthalpy are compared with direct information on both species as derived from their O-H fundamental modes.

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“…The chemistry of carboxylic acids, and in particular the self-association of acetic acid, has also been the subject of numerous spectroscopic and theoretical investigations. − This interest is due in part to the relatively simple structure of acetic acid as well as to the presence of both O···H−O and relatively weaker O···H−C hydrogen bonding. Infrared spectroscopic measurements of acetic acid have been performed in argon and nitrogen matrixes, − ,,, gas phase, ,,, liquid phase, , and solution. − ,,,, These measurements have revealed the presence of several acetic acid species, such as cis- and trans-monomers, cyclic dimer, open (linear) dimers, ,, and higher aggregates. , The matrix isolation spectroscopy investigations have been particularly effective in varying the ratios of monomer to dimer (because of changes in pulse duration etc. ), and this has aided the assignment of infrared bands.…”

Section: Introductionmentioning

confidence: 99%

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

Tjahjono

Cheng

et al. 2010

J. Phys. Chem. A

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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.

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Etude structurale des associationsde l'acide acetique en solution par spectroscopie infrarouge et calculs quantiques C.N.D.O./2

Cited by 7 publications

References 15 publications

Polymethacrylic Acid Shows Thermoresponsivity in an Organic Solvent

Polymethacrylic Acid Shows Thermoresponsivity in an Organic Solvent

Dimerization of Carboxylic Acids in Solution up to High Pressures and Temperatures. 1. Pivalic Acid

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

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