Cooperative Hydration of Pyruvic Acid in Ice

Guzmán, Marcelo I.; Hildebrandt, L.; Colussi, and A. J.; Hoffmann, Michael R.

doi:10.1021/ja062039v

Cited by 44 publications

(52 citation statements)

References 55 publications

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“…The effective absorption coefficients, ɛ eff ’s, of PA and BF in these experiments were evaluated from the convolution of their experimental absorption spectra in aqueous solution with the emission spectrum of the lamp. Since the extent of the partial hydration of keto‐PA ( k ‐PA), the actual chromophore, into transparent (above λ > 300 nm) 2,2‐dihydroxypropanoic acid ( h ‐PA) is an inverse function of temperature, the ɛ eff of PA determined in water at 293 K was scaled down [ ɛ eff (<270 K) = 0.69 × ɛ eff (293 K)] in frozen solutions according to the experimental ratios: [ h ‐PA] / [ k ‐PA] = 2.54 (293 K) and 4.10 ( T < 270 K) measured by 1 H‐NMR and reported elsewhere [ Buschmann et al , 1982; Buschmann et al , 1980; Guzmán et al , 2006c]. BF is barely hydrated under present conditions [ Fleury et al , 1977].…”

Section: Resultsmentioning

confidence: 99%

Photolysis of pyruvic acid in ice: Possible relevance to CO and CO₂ ice core record anomalies

2007

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The abnormal spikes detected in some CO and CO2 polar ice core records indicate persistent chemical activity in glacial ice. Since CO and CO2 spikes are correlated, and their amplitudes scale with reported CO/CO2 yields for the photolysis of dissolved natural organic matter, a common photochemical source is implicated. Given that sufficient actinic radiation is constantly generated throughout ice by cosmic muons (Colussi and Hoffmann, 2003), it remains to be shown that the photolyses of typical organic contaminants proceed by similar mechanisms in water and ice. Here we report that the photodecarboxylation of pyruvic acid (PA, an ubiquitous ice contaminant) indeed leads to the same products nearly as efficiently in both media. CO2 is promptly released from frozen PA/H2O films upon illumination and continues to evolve after photolysis. By analogy with our studies in water (Guzmán et al., 2006b), we infer that 3PA* reacts with PA in ice producing CH3C(O)C(O)O· and (CH3 (OH)C(O)OH) radicals. The barrierless decarboxylation, CH3C(O)C(O)O· → CH3C(O)· + CO2, accounts for prompt CO2 emissions down to ∼140 K. Bimolecular radical reactions subsequently ensue in fluid molecular environments, both in water and ice, leading to metastable intermediates that decarboxylate immediately in water, but protractedly in ice. The overall quantum yield of CO2 production in the λ ~313 nm photolysis of PA in ice at 250 K is ∼60% of that in water at 293 K. The in situ photolysis of natural organic matter is, therefore, a plausible explanation of CO and CO2 ice core record anomalies.

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Section: Resultsmentioning

confidence: 99%

Photolysis of pyruvic acid in ice: Possible relevance to CO and CO₂ ice core record anomalies

2007

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“…, rendering a different species above 190 K. Differential scanning calorimetry measurements, during the warming cycle, showed a single endotherm at the colligatively depressed melting point of water (Guzman et al, 2006c). Therefore, at high temperatures (e.g., > 235 K) this reaction proceeds in restricted liquid-like regions (Guzman et al, 2006a.…”

Section: Atmosmentioning

confidence: 98%

Organics in environmental ices: sources, chemistry, and impacts

et al. 2012

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Abstract. The physical, chemical, and biological processes involving organics in ice in the environment impact a number of atmospheric and biogeochemical cycles. Organic material in snow or ice may be biological in origin, deposited from aerosols or atmospheric gases, or formed chemically in situ. In this manuscript, we review the current state of knowledge regarding the sources, properties, and chemistry of organic materials in environmental ices. Several outstanding questions remain to be resolved and fundamental data gathered before an accurate model of transformations and transport of organic species in the cryosphere will be possible. For example, more information is needed regarding the quantitative impacts of chemical and biological processes, ice morphology, and snow formation on the fate of organic material in cold regions. Interdisciplinary work at the interfaces of chemistry, physics and biology is needed in order to fully characterize the nature and evolution of organics in the cryosphere and predict the effects of climate change on the Earth's carbon cycle.

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“…An understanding of the interfacial interactions between ice/snow and organic molecules comes from various studies, including those of physical and chemical properties of the ice surface (Engquist 1995a(Engquist , 1995bBertilsson et al, 1997Bertilsson et al, , 1999Wania et al, 1998;Roberts, 1999a, 1999b;Girardet and Toubin, 2001;Borodin et al, 2004;Gudipati, 2004;Roth et al, 2004;Guzmán et al, 2006a;Heger et al, 2005;Heger and Klán, 2007) and cryogenic chemical behavior of ice contaminants (Sumner and Shepson, 1999;Wania et al, 1999;Dubowski and Hoffmann, 2000;Klán and Holoubek, 2002;Coloussi and Hoffmann, 2003;Klán et al, 2003;Klánová et al, 2003aKlánová et al, , 2003bGrannas et al, 2004;Guzmán et al, 2006b;Heger et al, 2006). Adsorption of various organic molecules on ice surfaces can be described well with a multi-parameter linear free energy relationship, based on the van der Waals and the electron donor/acceptor interactions (such as H-bonding) (Roth et al, 2004 (Devlin, 1992;Devlin and Buch, 1995).…”

Section: Interaction Of Organics With Icementioning

confidence: 99%

An overview of snow photochemistry: evidence, mechanisms and impacts

et al. 2007

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Abstract. It has been shown that sunlit snow and ice plays an important role in processing atmospheric species. Photochemical production of a variety of chemicals has recently been reported to occur in snow/ice and the release of these photochemically generated species may significantly impact the chemistry of the overlying atmosphere. Nitrogen oxide and oxidant precursor fluxes have been measured in a number of snow covered environments, where in some cases the emissions significantly impact the overlying boundary layer. For example, photochemical ozone production (such as that occurring in polluted mid-latitudes) of 3-4 ppbv/day has been observed at South Pole, due to high OH and NO levels present in a relatively shallow boundary layer. Field and laboratory experiments have determined that the origin of the observed NO x flux is the photochemistry of nitrate within the snowpack, however some details of the mechanism have not yet been elucidated. A variety of low molecular weight organic compounds have been shown to be emitted from sunlit snowpacks, the source of which has been proposed to be either direct or indirect photo-oxidation of natural organic materials present in the snow. Although myriad studies have observed active processing of species within irradiated snowpacks, the fundamental chemistry occurring remains poorly understood. Here we consider the nature of snow at a fundamental, physical level; photochemical processes within snow and the caveats needed for comparison to atmospheric photochemistry; our current understanding of nitrogen, oxidant, halogen and organic photochemistry within snow; the current limitations faced by the field and implications for the future.

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Cooperative Hydration of Pyruvic Acid in Ice

Cited by 44 publications

References 55 publications

Photolysis of pyruvic acid in ice: Possible relevance to CO and CO₂ ice core record anomalies

Photolysis of pyruvic acid in ice: Possible relevance to CO and CO₂ ice core record anomalies

Organics in environmental ices: sources, chemistry, and impacts

An overview of snow photochemistry: evidence, mechanisms and impacts

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Cooperative Hydration of Pyruvic Acid in Ice

Cited by 44 publications

References 55 publications

Photolysis of pyruvic acid in ice: Possible relevance to CO and CO2 ice core record anomalies

Photolysis of pyruvic acid in ice: Possible relevance to CO and CO2 ice core record anomalies

Organics in environmental ices: sources, chemistry, and impacts

An overview of snow photochemistry: evidence, mechanisms and impacts

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Product

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Photolysis of pyruvic acid in ice: Possible relevance to CO and CO₂ ice core record anomalies

Photolysis of pyruvic acid in ice: Possible relevance to CO and CO₂ ice core record anomalies