Free-radical oxidation of isocyanic acid

Tully, Frank P.; Perry, R. A.; Thorne, L. R.; Allendorf, Mark D.

doi:10.1016/s0082-0784(89)80120-1

Cited by 21 publications

(23 citation statements)

References 12 publications

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“…Measurements of the low-temperature products of reaction (2) and the high-temperature values of kZtod or k26 are needed before the temperature dependence of the rate coefficients of individual product channels can be specified over a broad temperature range. Tully et al [2] also measured the overall rate coefficient of reaction (3) over the temperature range of 624 K to 875 K, and reported the following two-parameter fit to the measurements: k3 = 2.65 x 10" exp(-2790/T,K) cm3 mol-' s-'…”

Section: Oh Absorption Measurementsmentioning

confidence: 99%

“…However, there have been no previous 0 + HNCO -N H + COz 0 + HNCO -HNO + CO measurements of the rate coefficients of these individual product channels, and there has been only one direct measurement of the rate of the overall reaction: (2) 0 + HNCO -products Tully et al [2] measured the overall rate of reaction (2) at temperatures of 679 K and 741 K using a laser photolysis/NOz chemiluminescence technique in a heated quartz reactor. In work not yet published, Wu and Lin [3] have studied the role of reaction (2) in HNCO/NO/NO2/Ar reaction kinetics at temperatures between 2000 K and 2500 K by monitoring NO narrowlinewidth absorption of a CO laser in shock tube experiments. They observed accelerated NO-removal rates when NO2 was added to HNCO/NO/Ar mixtures which they attributed to increased radical production by reaction (2).…”

Section: Introductionmentioning

confidence: 99%

“…In work not yet published, Wu and Lin [3] have studied the role of reaction (2) in HNCO/NO/NO2/Ar reaction kinetics at temperatures between 2000 K and 2500 K by monitoring NO narrowlinewidth absorption of a CO laser in shock tube experiments. They observed accelerated NO-removal rates when NO2 was added to HNCO/NO/Ar mixtures which they attributed to increased radical production by reaction (2).…”

Section: Introductionmentioning

confidence: 99%

“…This makes it possible to determine an upper limit on the rate coefficient of (3) OH + HNCO -products using the OH measurements over the temperature range of 2120 K to 2350 K. Tully et al [2] measured the overall rate coefficient of reaction (3) at temperatures ranging from 624 K and 875 K in the only previous direct measurement of k3.…”

Section: Introductionmentioning

confidence: 99%

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A shock tube study of reactions of atomic oxygen with isocyanic acid

Mertens

Chang

Hanson

et al. 1992

Int J of Chemical Kinetics

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Reactions of atomic oxygen with isocyanic acid (HNCO) have been studied in incident and reflected shock wave experiments using HNCO/NZO/Ar mixtures. Quantitative time-histories of the NH(X38-) and OH(X2n,) radicals were measured behind the shock waves using cw, narrow-linewidth laser absorption at 336 nm and 307 nm, respectively. The second-order rate coefficients of the reactions: 0 + HNCO --j OH + NCO were determined from early-time NH and OH formation rates, with least-squares twoparameter fits of the results given by:

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Section: Oh Absorption Measurementsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A shock tube study of reactions of atomic oxygen with isocyanic acid

Mertens

Chang

Hanson

et al. 1992

Int J of Chemical Kinetics

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“…HNCO has a lifetime of decades towards OH radicals in the atmosphere as estimated by extrapolating high temperature rate coefficients to atmospheric temperatures (Tsang, 1992;Mertens et al, 1992;Tully et al, 1989). It is also not expected to photolyze in the actinic region since its first UV absorption band is observed below 280 nm wavelengths (Brownsword et al, 1996;Dixon and Kirby, 1968;Rabalais et al, 1969).…”

Section: Introductionmentioning

confidence: 99%

Solubility and reactivity of HNCO in water: insights into HNCO's fate in the atmosphere

et al. 2016

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Abstract.A growing number of ambient measurements of isocyanic acid (HNCO) are being made, yet little is known about its fate in the atmosphere. To better understand HNCO's loss processes and particularly its atmospheric partitioning behaviour, we measure its effective Henry's Law coefficient K eff H with a bubbler experiment using chemical ionization mass spectrometry as the gas phase analytical technique. By conducting experiments at different pH values and temperature, a Henry's Law coefficient K H of 26 ± 2 M atm −1 is obtained, with an enthalpy of dissolution of −34 ± 2 kJ mol −1 , which translates to a K eff H of 31 M atm −1 at 298 K and at pH 3. Our approach also allows for the determination of HNCO's acid dissociation constant, which we determine to be K a = 2.1 ± 0.2 × 10 −4 M at 298 K. Furthermore, by using ion chromatography to analyze aqueous solution composition, we revisit the hydrolysis kinetics of HNCO at different pH and temperature conditions. Three pH-dependent hydrolysis mechanisms are in play and we determine the Arrhenius expressions for each rate to be k 1 = (4.4 ± 0.2) × 10 7 exp(−6000 ± 240/T ) M s −1 , k 2 = (8.9 ± 0.9) × 10 6 exp(−6770 ± 450/T ) s −1 and k 3 = (7.2 ± 1.5) × 10 8 exp(−10 900 ± 1400/T ) s −1 , where k 1 is for HNCO + H + + H 2 O → NH + 4 + CO 2 , k 2 is for HNCO + H 2 O → NH 3 + CO 2 and k 3 is for NCO − + 2 H 2 O → NH 3 + HCO − 3 . HNCO's lifetime against hydrolysis is therefore estimated to be 10 days to 28 years at pH values, liquid water contents, and temperatures relevant to tropospheric clouds, years in oceans and months in human blood. In all, a better parameterized Henry's Law coefficient and hydrolysis rates of HNCO allow for more accurate predictions of its concentration in the atmosphere and consequently help define exposure of this toxic molecule.

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Computational study of the reaction of C₃H₃ with HNCO and the decomposition of C₄H₄NO radicals

Nguyễn

Trang

Nguyen

et al. 2022

Int J of Chemical Kinetics

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Ab initio CCSD(T)/CBS(T,Q,5)//M06-2X/aug-cc-pVTZ calculations have been applied to figure out the C 4 H 4 NO (isopropyl aminocarbonyl) potential energy surface (PES). The resulting energetics and molecular parameters of all species involved in the system have been then employed in the TST and RRKM/ME computations of temperature-and pressure-dependent rate coefficients and product yields. The calculated results show that rate constants of the abstraction reactions C 3 H 3 + HNCO → C 3 H 4 + NCO are pressure-independent while those of the addition reactions C 3 H 3 + HNCO and the C 4 H 4 NO decomposition reactions were found to be pressure-dependent. The calculated enthalpies of formation for species involved in the system are in good ageement with the available literature data. All the results of this work may provide a useful database source for the further study of this kind of reactions.

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Free-radical oxidation of isocyanic acid

Cited by 21 publications

References 12 publications

A shock tube study of reactions of atomic oxygen with isocyanic acid

A shock tube study of reactions of atomic oxygen with isocyanic acid

Solubility and reactivity of HNCO in water: insights into HNCO's fate in the atmosphere

Computational study of the reaction of C₃H₃ with HNCO and the decomposition of C₄H₄NO radicals

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Free-radical oxidation of isocyanic acid

Cited by 21 publications

References 12 publications

A shock tube study of reactions of atomic oxygen with isocyanic acid

A shock tube study of reactions of atomic oxygen with isocyanic acid

Solubility and reactivity of HNCO in water: insights into HNCO's fate in the atmosphere

Computational study of the reaction of C3H3 with HNCO and the decomposition of C4H4NO radicals

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Computational study of the reaction of C₃H₃ with HNCO and the decomposition of C₄H₄NO radicals