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Spectrokinetic Study of the Reaction System of 2NO2"N2O4 with Butanols Between 320-358 K in the Gas Phase

Wójcik-Pastuszka D., Jodkowski J. T.

Polish Journal of Chemistry

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2009

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Vol. 83, nr 1

131-143

EN

Spectrokinetic studies of the gas-phase equilibrium between nitrogen tetroxide and butanols in the reaction system 2NO2"N2O4 (1, 2), N2O4+ROH"RONO+HNO3 (3, 4) have been undertaken in the temperature range 298-358 K. The products - RONO (n-butyl-ONO, sec-butyl-ONO, iso-butyl-ONO and tert-butyl-ONO) - were identified by their UV spectra and the values of the maxima UV absorption cross sections were determined in the range 320-420 nm at 298 K. The temperature dependences of both the forward and reverse rate constants, k3 and k4, were obtained. The extrapolated values of the forward rate constants are 10-18 k3av /cm3 molec-1 s-1 3.9 plus-minus 1.0; 1.7 plus-minus 0.3; 4.2 plus-minus 0.8; 5.7 plus-minus 1.1 and the reverse rate constants are 10-20 k4av /cm3 molec-1 s-1 0.3plus-minus 0.1; 2.3 plus-minus 0.6; 0.4 plus-minus 0.1; 2.3 plus-minus 0.6 at 298 K for the reaction of NO2/N2O4 with n-butanol, sec-butanol, iso-butanol and tert-butanol, respectively. The activation energy for the forward E3 and for the reverse E4 reaction were derived.

2

Spectrokinetic Study of the Reaction System of 2NO2_N2O4 with Some Fluorinated Derivatives of Ethanol and Propanols Between 293-358 K in the Gas Phase

Wójcik-Pastuszka D., Golonka I., Ratajczak E.

Polish Journal of Chemistry

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2006

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Vol. 80, nr 9

1559-1574

EN

The gas phase kinetics of the reversible reactions between nitrogen tetroxide and some fluorinated alcohols in the reaction system 2NO2_N2O4 (1, 2) N2O4+ ROH--RONO + + HNO3 (3, 4) have been studied by UV-Vis spectrophotometry to follow the NO2 decay. The products - RONO (R = CH2FCH2, CHF2CH2, CF3CH2, CHF2CF2CH2, CF3CF2CH2, CF3CHCF3) - were identified by their UV spectra and the values of the maxima UV absorption cross sections were determined in the range 320-400 nm. The rate constants for the forward reaction are 10-19k3 av /cm3molec-1s-1 9.7š1.5; 2.5š0.4; 1.8š0.3; 23š3.5, 2.3š0.3, 0.2š0.03 and for the reverse reaction 10-19k4 av /cm3molec-1s-1 4.6š0.7; 5.5š0.8; 4.9š0.7; 9.1š1.4; 7.7š1.2; 23š3.5 at 298 K for the reaction with 2-fluoroethanol, 2,2-difluoroethanol, 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoro-1-propanol, 2,2,3,3,3-pentafluoro- 1-propanol and 1,1,1,3,3,3-hexafluoro-2-propanol, respectively, were derived by the computer simulation of monitored NO2 decay profiles. The temperature dependence of the bimolecular rate constants k3 and k4 were studied in the temperature range 293-358 K and the activation energy for the forward E3 and for the reverse E4 reaction were derived. From the observed temperature dependence of the equilibrium constants K3,4 , expressed in terms of the van't Hoff equation, the thermochemical parameters for all reactions studied were estimated.

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Gas Phase Kinetics of the Reaction System of 2NO2--N2O4 and Simple Alcohols Between 293-358 K

Wójcik-Pastuszka D., Gola A., Ratajczak E.

Polish Journal of Chemistry

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2005

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Vol. 79 / nr 8

1301-1313

EN

The reversible reactions between nitrogen dioxide and alcohols (CH3OH, CH3CH2OH, CH3CH2CH2OH, CH3CHOHCH3) have been studied in the gas phase, using the spectrophotometric method.RONO(R = CH3, CH3CH2, CH3CH2CH2, CH3CHCH3) were identified by UV spectra. The equilibrium constants as well as the bimolecular rate constants were determined by computer modeling, using the programme MINICHEM. We calculated the following values for the forward rate constants k3 av : (3.0_0.9)x10-18, (8.0+-2.4)X10-18, (5.4+-1.6)_10-18, (2.0+-0.6)x10-18 cm3 molec-1 s-1 and the equilibrium constants Kav: 100+-30, 40+-12, 109+-33, 39+-12 at 298 K for the reactions with methanol, ethanol, 1-propanol and 2-propanol, respectively. The temperature dependence of the rate constants and the equilibrium constants were studied and it allowed to obtain the activation energy for the forward and for the reverse reaction, as well as thermochemical parameters. The equilibrium constants and the rate constants suggest that symmetrical N2O4 is the reactive species.

4

Laboratory studies of the reaction between nitrogen dioxide and ammonia in the temperature range of 288-357 K

Pagsberg P., Sillesen A., Brudnik K., Ratajczak E.

Bulletin of the Polish Academy of Sciences. Chemistry

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2001

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Vol. 49, No. 4

299-304

EN

The title reaction has been studied by infrared tunable diode laser spec-troscopy which allows for the detection of both reactant and product molecules. The decay rate of ammonia in the presence of nitrogen dioxide was found to be second order with respect to the concentration of NO2- The simultaneous formation of water was found to occur with a relative yield of 4[H2O] = —0.5^[NH3]. The formation of aerosols containing crystalline ammonium nitrate implies that nitric acid is also a primary reaction product in the overall reaction 2NO2 + 2NHa —> N2 + H(2)O + NH(4)NOs. A reaction mechanism involving asym-N(2)O(4) reacting with NHa has been tested by detailed computer modelling which was used to account for all of the observed kinetic and mechanistic features. For the rate controlling step 2NO2 + M —> asym- N2C>4 + M (1) we have determined an apparent bimolecular rate constant of k\ — 2.30 x 10(-4) x exp(3838 =360/T)M(-1)s(-1) at a total pressure of 30 mbar.