920-42-3Relevant articles and documents
Isotope Exchange Reaction of Formate with Molecular Hydrogen on Ni(110) by IRAS
Yamakata, Akira,Kubota, Jun,Kondo, Junko N.,Domen, Kazunari,Hirose, Chiaki
, p. 18177 - 18182 (1996)
Kinetics of the CH/CD isotope exchange reaction of formate (HCOO(a)/DCOO(a)) on Ni(110) with gaseous D2/H2 was investigated below the decomposition temperature (360 K) by infrared reflection absorption spectroscopy (IRAS).The apparent activation energies of HCOO(a) -> DCOO (a) and DCOO(a) -> HCOO(a) reactions were derived as 52 +/- 5 and 58 +/- 5 kJ*mol-1, respectively.A half-order dependence of the reaction rate on hydrogen pressure was observed, suggesting that the rate-determining step was the reaction of the adsorbed formate with reversibly adsorbed hydrogen atom The reaction of HCOO(a) with D2 was 2.1 +/- 0.3 times faster than that of DCOO(a) with H2 at 300 K, and the origin of the isotope effect is discussed.
Formation of Glyoxylic Acid in Interstellar Ices: A Key Entry Point for Prebiotic Chemistry
Eckhardt, André K.,Bergantini, Alexandre,Singh, Santosh K.,Schreiner, Peter R.,Kaiser, Ralf I.
supporting information, p. 5663 - 5667 (2019/03/29)
With nearly 200 molecules detected in interstellar and circumstellar environments, the identification of the biologically relevant α-keto carboxylic acid, glyoxylic acid (HCOCOOH), is still elusive. Herein, the formation of glyoxylic acid via cosmic-ray driven, non-equilibrium chemistry in polar interstellar ices of carbon monoxide (CO) and water (H2O) at 5 K via barrierless recombination of formyl (HCO) and hydroxycarbonyl radicals (HOCO) is reported. In temperature-programmed desorption experiments, the subliming neutral molecules were selectively photoionized and identified based on the ionization energy and distinct mass-to-charge ratios in combination with isotopically labeled experiments exploiting reflectron time-of-flight mass spectrometry. These studies unravel a key reaction path to glyoxylic acid, an organic molecule formed in interstellar ices before subliming in star-forming regions like SgrB2(N), thus providing a critical entry point to prebiotic organic synthesis.
A biomimetic photoelectrocatalyst of Co-porphyrin combined with a g-C3N4 nanosheet based on π-π Supramolecular interaction for high-efficiency CO2 reduction in water medium
Liu, Jibo,Shi, Huijie,Shen, Qi,Guo, Chenyan,Zhao, Guohua
supporting information, p. 5900 - 5910 (2017/12/26)
Aiming at high-efficiency biomimetic CO2 photoelectrochemical conversion, a photoelectrocatalyst with excellent CO2 catalytic activity was designed and prepared by immobilizing CoTPP (cobalt meso-tetraphenylporphyrin) onto g-C3N4 conveniently via self-assembly based on π-π supramolecular interaction. The quasi 3-D structure of CoTPP showed a suitable hole with a size of 3.8 ? × 9.6 ? which favoured CO2 adsorption. The pores formed by the π-π stacking of CoTPP and g-C3N4 also provided additional space for CO2 adsorption, which was confirmed by the appearance of a desorption peak at 250 °C in the temperature programmed desorption measurement for CoTPP/g-C3N4. As a normal efficient homogeneous catalyst in organic media, CoTPP commendably maintained outstanding CO2 photoelectrocatalytic activity in heterogeneous aqueous solution, even at a low overpotential of -0.6 V (vs. normal hydrogen electrode, NHE). Under 8 h PEC CO2 reduction, formic acid generation on CoTPP/g-C3N4 reached 154.4 μmol with a TON of 137 and high selectivity of nearly 100% in liquid products. The formation of CoTPP-COO- and CoTPP-COOH intermediates by the Co(ii) active site and CO2 was investigated by in situ UV-vis and Raman spectra. Moreover, an isotopic labelling experiment indicated that water supplied abundant protons for the production of formic acid.
Precision measurement of the quadrupole coupling and chemical shift tensors of the deuterons in α-calcium formate
Schmitt, Heike,Zimmermann,Koerner,Stumber,Meinel,Haeberlen
, p. 65 - 77 (2007/10/03)
Using calcium formate, α-Ca(DCOO)2, as a test sample, we explore how precisely deuteron quadrupole coupling (QC) and chemical shift (CS) tensors Q and σ can currently be measured. The error limits, ±0:09 kHz for the components of Q and ±0:06 ppm for those of σ, are at least three times lower than in any comparable previous experiment. The concept of a new receiver is described. A signal/noise ratio of 100 is realized in single-shot FT spectra. The measurement strategies and a detailed error analysis are presented. The precision of the measurement of Q is limited by the uncertainty of the rotation angles of the sample and that of σ by the uncertainty of the phase correction parameters needed in FT spectroscopy. With a 4-sigma confidence, it is demonstrated for the first time that the unique QC tensor direction of a deuteron attached to a carbon deviates from the bond direction; the deviation found is (1:2±0:3°). Evidence is provided for intermolecular QC contributions. In terms of Q, their size is roughly 4 kHz. The deuteron QC tensors in α-Ca(DCOO)2 (two independent deuteron sites) are remarkable in three respects. For deuterons attached to sp2 carbons, first, the asymmetry factors η and, second, the quadrupole coupling constants CQ, are unusually small, η1 = 0:018; η2 = 0:011, and CQ1 = (151:27±0:06) kHz, CQ2 = (154:09±0:06) kHz. Third, the principal direction associated with the largest negative QC tensor component lies in and not, as usual, perpendicular to the molecular plane. A rationalization is provided for these observations. The CS tensors obtained are in quantitative agreement with the results of an earlier, less precise, line-narrowing multiple-pulse study of α-Ca(HCOO)2. The assignment proposed in that work is confirmed. Finally we argue that a further 10-fold increase of the measurement precision of deuteron QC tensors, and a 2-fold increase of that of CS tensors, should be possible. We indicate the measures that need to be taken.
