An experimental and computational IR and hybrid DFT-D3 study of the conformations of<scp>l</scp>-lactic and acrylic acid: new insight into the dehydration mechanism of lactic acid to acrylic acid

Zeinalipour-Yazdi, Constantinos D.; Catlow, C. Richard A.

doi:10.1039/c9cp02968k

Cited by 5 publications

(3 citation statements)

References 37 publications

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“…Relative Gibbs energies, Δ G , are calculated against the most stable conformer, SsC. These abundances are in good agreement with previous computational studies on lactic acid. ,− These prior studies used a variety of methods, including Hartree–Fock (also known as SCF) calculations, MP2 with different basis sets, ,,− and DFT with different functional and basis set combinations. , …”

Section: Resultssupporting

confidence: 81%

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Lactic Acid Spectroscopy: Intra- and Intermolecular Interactions

et al. 2020

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Lactic acid, a relevant molecule in biology and the environment, is an α-hydroxy acid with a high propensity to form hydrogen bonds, both internally and to other hydrogen-bond-accepting molecules. This work includes the novel recording of infrared spectra of gas-phase lactic acid using Fourier transform infrared spectroscopy, and the vibrational absorption features of lactic acid are assigned with the aid of computationally simulated vibrational spectra with anharmonic corrections. Theoretical chemistry methods are used to relate intramolecular hydrogen-bond strengths to the relative stability of lactic acid conformers. The formation of hydrogen-bonded lactic acid dimers and 1:1 water complexes is investigated by simulated vibrational spectra and calculated thermodynamic parameters for the lactic acid monomer and dimer and its water complex in the gas phase. The results of this study are discussed in the context of environmental chemistry with an emphasis on indoor environments.

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Section: Resultssupporting

confidence: 81%

“…between the Different Lactic Acid Conformers (conf.) Using Theoretical (This Work and Zeinalipour-Yazdi et al65 ) and Experimental Results (Borba et al59 ) . 65 a this work b Borba et al59 (Ar/Xe) c…”

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confidence: 99%

Lactic Acid Spectroscopy: Intra- and Intermolecular Interactions

et al. 2020

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“…Four main conformers of lactic acid in the gas phase as identified previously and using the naming convention established therein. ,− Relative abundances are from ref .…”

Section: Resultsmentioning

confidence: 99%

Oxygen Effect on the Ultraviolet-C Photochemistry of Lactic Acid

Deal

Vaida

2023

J. Phys. Chem. A

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Lactic acid, a small α-hydroxyacid, is ubiquitous in both indoor and outdoor environments. Recently, the photochemistry of lactic acid has garnered interest among the abiotic organic chemistry community as it would have been present in abiotic settings and photoactive with the high-energy solar radiation that would have been available in the low oxygen early Earth environment. Additionally, we propose that the photochemistry of lactic acid is relevant to modern Earth during indoor ultraviolet-C (UVC) sterilization procedures as lactic acid is emitted by humans and is thus prevalent in indoor environments where UVC sterilization is increasingly being used. Here, we study the oxygen effect on the gas phase photolysis of lactic acid using Fourier-transform infrared (FTIR) spectroscopy and isotopically labeled oxygen (18O2). We find that the major products of gas phase lactic acid photolysis are CO2, CO, acetaldehyde, and acetic acid. Furthermore, these products are the same with or without added oxygen, but the partial pressures of produced CO2, CO, and acetaldehyde increase with the amount of added oxygen. Notably, the added oxygen is primarily incorporated into produced CO2 and CO, while little or none is incorporated into acetaldehyde. We combine the results presented here with those in the literature to propose a mechanism for the gas phase photolysis of lactic acid and the role of oxygen in this mechanism. Finally, we compare the output of a krypton-chloride excimer lamp (λ = 222 nm), one of the lamps proposed for UVC sterilization procedures, to the absorption of lactic acid. We show that lactic acid would be photoactive during UVC sterilization procedures, and we use the gas phase results presented here and aqueous lactic acid photolysis results previously published to assess potential byproducts from lactic acid reactions during UVC sterilization procedures.

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