A Kinetic Study of the Hydrolysis of Phosgene in Aqueous Solution by Pulse Radiolysis

Mertens, Ralf; Sonntag, Clemens von; Lind, Johan; Merényi, Gábor

doi:10.1002/anie.199412591

Cited by 52 publications

(46 citation statements)

References 13 publications

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“…These eliminate HCl within less than a few microseconds (cf. [44]) and hence a reaction sequence such as (7) followed by (9) is readily detected in a pulse radiolysis experiment using conductometry for detection. Practically no HCl is liberated at the microseconds time scale indicating that reaction (7) is of little importance.…”

Section: Methodsmentioning

confidence: 99%

Products and Kinetics of the OH-radical-induced Dealkylation of Atrazine

Tauber

Sonntag

2000

Acta hydrochim. hydrobiol.

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Hydroxyl radicals, generated radiolytically in N2O/O2‐saturated solutions, yield in their reaction with atrazine equal amounts of deethylatrazine and acetaldehyde (40% of OH radical yield) and deisopropylatrazine and acetone (16%), respectively. The precursors of deethylatrazine and acetaldehyde is their Schiff base which hydrolyzes slowly (OH–‐catalyzed: k = 5.2 dm3 mol–1 s–1). The hydrolysis of the Schiff base of deisopropylatrazine and acetone is too fast to be detected. In a pulse radiolysis experiment, the intermediate formed upon OH‐radical attack (k = 3·109 dm3 mol–1 s–1) has a strong absorption at 440 nm. It decays in the presence of oxygen (k = 1.3·109 dm3 mol–1 s–1), and upon deprotonation [pKa(peroxyl radicals) ≈ 10.5] the peroxyl radicals thus‐formed eliminate superoxide radicals (k = 2.9·105 s–1). s‐Triazine itself reacts much more slowly with OH radicals (k = 9.7·107 dm3 mol–1 s–1). This can explain, why in the case of atrazine in comparison to other aromatic compounds, e.g. toluene, the addition of the OH radical to the ring (estimated at ca. 40%) is of relatively little importance as compared to an H‐abstraction from (activated) positions of the side groups.

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Section: Methodsmentioning

confidence: 99%

Products and Kinetics of the OH-radical-induced Dealkylation of Atrazine

Tauber

Sonntag

2000

Acta hydrochim. hydrobiol.

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“…[10] The existence of a vinyl-type radical structure is further supported by the observation of a typical vinyl peroxyl radical band [11] in oxygen saturated butyl chloride solutions containing TPGDA.…”

Section: Cationic Pathway Of Radical Formation -Discussionmentioning

confidence: 67%

Radical formation in electron-irradiated acrylates studied by pulse radiolysis and electron paramagnetic resonance

Mehnert¹,

Naumov

Knolle

et al. 2000

Macromol. Chem. Phys.

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Electron pulse radiolysis with optical and conductometric detection as well as low‐temperature electron paramagnetic resonance (EPR) were used to study the mechanism of electron‐irradiation induced polymerisation and cross‐linking of acrylates such as triethyleneglycol (TPGDA) and butandiol (BDDA) diacrylate. Irradiation of acrylates with fast electrons generates radical cations and anions that rapidly transform to radicals. Using butyl chloride or tetrahydrofuran and water as solvents cationic and anionic pathways of radical formation were studied separately. Acrylate radical cations either deprotonate forming vinyl‐type radicals or generate covalently bonded or resonance stabilised dimer cations. Vinyl‐type radicals as well as dimer cations are able to initiate polymerisation. EPR results show that a structural transformation of TPGDA primary cations takes place by H‐transfer from the ester to the positively charged carbonyl group. Addition of solvated electrons to acrylates forms anions. Protonation of the anion at the carbonyl site leads to ketyl‐type radicals which are also able to initiate polymerisation. It is concluded that after electron‐irradiation of acrylates both cations as well as anions are important precursors of radicals which induce radical polymerisation and cross‐linking.

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“…The results from Mirabel's group are derived from an analysis of droplet train uptake data that is essentially the same as that used in the Aerodyne Research, Inc./Boston College effort. Additional literature values of k hyd and H for CC1 2 0 (which has not yet been studied by the Mirabel group) are also listea (9)(10)(11)(12). The uptake parameters derived from the experimental results of Mirabel and coworkers (3,4) are significanUy larger than those deduced from the Aerodyne Research/ Boston College data (6,7).…”

Section: Halocarbonyl Uptake Resultsmentioning

confidence: 93%

“…The resulting Hk hyd product of 3.8 ± 1.3 MatnrV 1 is also shown in Table II, along with a separate measurement of Hk hyd 1/2 of 0.17 from a 298 K wetted wall flow tube from the same laboratory. Finally, an older aqueous jet study by Manogue and Pigford (9) as well as a very recently published measurement of k nyd using a novel pulsed radiolysis source of this reactant by Mertens et al (12), both for C0 2 0, are included in Table II. These C0 2 0 results all agree reasonably well with the ARI/BC result and disagree strongly with the very high k hyd value measured by Ugi and Beck for this compound (10).…”

Section: Halocarbonyl Uptake Resultsmentioning

confidence: 99%

Heterogeneous Atmospheric Chemistry of Alternative Halocarbon Oxidation Intermediates

Kolb

Worsnop

Zahniser

et al. 1997

ACS Symposium Series

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Alternative halocarbons designed to substitute for chlorofluorocarbons and halons banned by the Montreal Protocol are designed to undergo oxidative degradation in the troposphere.Intermediate partially oxygenated products from currently used alternatives include carbonyl halides, haloacetyl halides and haloacetic acids. These intermediates are expected to undergo heterogeneous reactions with aqueous cloud droplets and surface waters. The chemical and physical parameters which govern the heterogeneous uptake of a range of these species by liquid water have been measured in our laboratories using droplet train/flow tube and/or bubble column techniques. The results of these experiments will be presented and compared with available results from other laboratories. Their impact on our ability to predict the atmospheric fate of halocarbon oxidation intermediates will be discussed. Atmospheric Fate of Alternative Halocarbon Oxidation ProductsAlternative halocarbons planned as substitutes for chlorofluorocarbons and halons banned by the Montreal Protocol are designed to undergo oxidative degradation in the troposphere. Intermediate partially oxygenated products from currently used or proposed alternatives include carbonyl halides, haloacetyl halides and haloacetic acids. A wide variety of atmospheric processes could participate in the removal of relatively stable degradation intermediates, including: transport to the stratosphere followed by photolysis, uptake by both tropospheric and stratospheric aerosols, uptake by cloud droplets, rainout (wet deposition), and dry deposition to vegetation, soil and dew surfaces, and to the oceans. However, recent model analyses indicate that cloud droplet and ocean uptake are the most likely removal rate determining processes. The physicochemical processes which are important in determining the rate of trace atmospheric gas uptake by liquid surfaces include gas phase diffusion, mass accommodation, solvation (Henry's law solubility), liquid phase diffusion and liquid phase reaction. The most effective removal paths and their associated physicochemical parameters are displayed in Table I. Key parameters affecting atmospheric removal rates are the mass accommodation coefficient, a, the Henry's law constant, H, and the first order hydrolysis reaction rate coefficient, k hyd .

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A Kinetic Study of the Hydrolysis of Phosgene in Aqueous Solution by Pulse Radiolysis

Cited by 52 publications

References 13 publications

Products and Kinetics of the OH-radical-induced Dealkylation of Atrazine

Products and Kinetics of the OH-radical-induced Dealkylation of Atrazine

Radical formation in electron-irradiated acrylates studied by pulse radiolysis and electron paramagnetic resonance

Heterogeneous Atmospheric Chemistry of Alternative Halocarbon Oxidation Intermediates

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