Carbonyl fluoride formation by cw-CO2 laser-induced and sulfur hexafluoride-sensitized decomposition of hexafluoroacetone

1981 ◽  
Vol 46 (5) ◽  
pp. 1254-1257 ◽  
Author(s):  
Josef Pola ◽  
Pavel Engst ◽  
Milan Horák
Keyword(s):  
Gas Phase ◽  
Co2 Laser ◽  
Sulfur Hexafluoride ◽  
Phase Decomposition ◽  
First Order ◽  
First Order Kinetics ◽  
Cw Co2 Laser ◽  
Carbonyl Fluoride

The cw-CO2 laser-induced gas phase decomposition of hexafluoroacetone sensitized with sulfur hexafluoride (both 0.7-5.2 kPa) affords, besides perfluorinated hydrocarbons and minor amounts of trifluoroacetyl fluoride, carbonyl fluoride the formation of that obeys first-order kinetics and is favored with higher SF6 content.

Catalysis by hydrogen halides in the gas phase. XIX. 2,3-Dimethylbutan-2-ol and hydrogen bromide

1968 ◽  
Vol 21 (10) ◽  
pp. 2385 ◽  
Author(s):  
RL Johnson ◽  
VR Stimson
Keyword(s):  
Gas Phase ◽  
Arrhenius Equation ◽  
Hydrogen Bromide ◽  
Phase Decomposition ◽  
Hydrogen Halides ◽  
First Order

The gas-phase decomposition of 2,3-dimethylbutan-2-ol into 2,3-dimethylbut-1-ene, 2,3-dimethylbut-2-ene, and water, catalysed by hydrogen bromide at 303-400�, is described. The rate is first-order in each reactant and the Arrhenius equation k2 = 1011.88 exp(-26490/RT) sec-l ml mole-1 is followed. The olefins appear to be in their equilibrium proportions. The effects of substitutions in the alcohol at Cα and Cβ on the rate are discussed.

scholarly journals Rapid compressions in a captive bubble apparatus are isothermal

2003 ◽  
Vol 95 (5) ◽  
pp. 1896-1900
Author(s):  
Wenfei Yan ◽  
Stephen B. Hall
Keyword(s):  
Hydrostatic Pressure ◽  
Gas Phase ◽  
Pulmonary Surfactant ◽  
First Order ◽  
First Order Kinetics ◽  
Gas Phase Molecules ◽  
Actual Change ◽  
Phase Temperature ◽  
Two Phases ◽  
Interfacial Films

Captive bubbles are commonly used to determine how interfacial films of pulmonary surfactant respond to changes in surface area, achieved by varying hydrostatic pressure. Although assumed to be isothermal, the gas phase temperature (Tg) would increase by >100°C during compression from 1 to 3 atm if the process were adiabatic. To determine the actual change in temperature, we monitored pressure (P) and volume (V) during compressions lasting <1 s for bubbles with and without interfacial films and used P · V to evaluate Tg. P · V fell during and after the rapid compressions, consistent with reductions in n, the moles of gas phase molecules, because of increasing solubility in the subphase at higher P. As expected for a process with first-order kinetics, during 1 h after the rapid compression P · V decreased along a simple exponential curve. The temporal variation of n moles of gas was determined from P · V >10 min after the compression when the two phases should be isothermal. Back extrapolation of n then allowed calculation of Tg from P · V immediately after the compression. Our results indicate that for bubbles with or without interfacial films compressed to >3 atm within 1 s, the change in Tg is <2°C.

Kinetics of NO2 air space absorption in isolated rat lungs

1992 ◽  
Vol 73 (5) ◽  
pp. 1939-1945 ◽  
Author(s):  
E. M. Postlethwait ◽  
S. D. Langford ◽  
A. Bidani
Keyword(s):  
Steady State ◽  
Tidal Volume ◽  
Gas Phase ◽  
Initial Rate ◽  
Quasi Steady State ◽  
Closed Chamber ◽  
First Order ◽  
First Order Kinetics ◽  
Rat Lungs ◽  
Kinetics Of

We previously showed, during quasi-steady-state exposures, that the rate of inhaled NO2 uptake displays reaction-mediated characteristics (J. Appl. Physiol. 68: 594–603, 1990). In vitro kinetic studies of pulmonary epithelial lining fluid (ELF) demonstrated that NO2 interfacial transfer into ELF exhibits first-order kinetics with respect to NO2, attains [NO2]-dependent rate saturation, and is aqueous substrate dependent (J. Appl. Physiol. 71: 1502–1510, 1991). We have extended these observations by evaluating the kinetics of NO2 gas phase disappearance in isolated ventilating rat lungs. Transient exposures (2–3/lung at 25 degrees C) employed rebreathing (NO2-air) from a non-compliant continuously stirred closed chamber. We observed that 1) NO2 uptake rate is independent of exposure period, 2) NO2 gas phase disappearance exhibited first-order kinetics [initial rate (r*) saturation occurred when [NO2] > 11 ppm], 3) the mean effective rate constant (k*) for NO2 gas phase disappearance ([NO2] < or = 11 ppm, tidal volume = 2.3 ml, functional residual capacity = 4 ml, ventilation frequency = 50/min) was 83 +/- 5 ml/min, 4) with [NO2] < or = 11 ppm, k* and r* were proportional to tidal volume, and 5) NO2 fractional uptakes were constant across [NO2] (< or = 11 ppm) and tidal volumes but exceeded quasi-steady-state observations. Preliminary data indicate that this divergence may be related to the inspired PCO2. These results suggest that NO2 reactive uptake within rebreathing isolated lungs follows first-order kinetics and displays initial rate saturation, similar to isolated ELF.(ABSTRACT TRUNCATED AT 250 WORDS)

Catalysis by hydrogen halides in the gas phase. XXIII. 1,1-Dimethoxyethane and hydrogen bromide

1971 ◽  
Vol 24 (5) ◽  
pp. 961 ◽  
Author(s):  
VR Stimson
Keyword(s):  
Gas Phase ◽  
Vinyl Ether ◽  
Arrhenius Equation ◽  
Hydrogen Bromide ◽  
Phase Decomposition ◽  
Hydrogen Halides ◽  
Methyl Vinyl ◽  
First Order ◽  
Methyl Vinyl Ether

Hydrogen bromide catalyses the gas-phase decomposition of 1,1- dimethoxy-ethane at 233-322� into methyl vinyl ether and methanol. The reaction, first-order in each reactant, is believed to be homogeneous and molecular. ��� The Arrhenius equation ������ �����������k2 = 1.3x1013exp(-22160/RT) s-1 cm3 mol-1 is followed. This decomposition is much faster than the analogous reactions of alcohols and ethers. The catalyst is effective when present in only 1% proportion.

IR laser induced decomposition of trifluoroacetic, pentafluoropropionic and heptafluorobutyric anhydrides

1990 ◽  
Vol 55 (10) ◽  
pp. 2460-2467 ◽  
Author(s):  
Pavel Kubát ◽  
Josef Pola
Keyword(s):  
Gas Phase ◽  
Sulfur Hexafluoride ◽  
Continuous Wave ◽  
Parent Compound ◽  
Theoretical Treatment ◽  
Phase Decomposition ◽  
Ir Laser ◽  
Mndo Calculations ◽  
Induced Decomposition ◽  
Heptafluorobutyric Anhydride

The continuous-wave CO2 laser induced gas-phase decomposition of trifluoroacetic, pentafluoropropionic and heptafluorobutyric anhydride, sensitized by sulfur hexafluoride was studied in order to determine the course of the reactions in the absence of wall effects. The decompositions of all the compounds are assumed to involve cleavage of parent compound into acyl fluoride F(CF2)nCOF and .(CF2)nCO2. biradical, the latter undergoing decay into CO and F(CF2)n-1COF compounds. The theoretical treatment of the biradical by MNDO calculations as well as trapping with ethene are presented.

A comparative study of the SF6-sensitized interaction of a cw-CO2 laser radiation with methyltrichloro derivatives of carbon, silicon and germanium

1981 ◽  
Vol 46 (12) ◽  
pp. 3088-3096 ◽  
Author(s):  
Josef Pola ◽  
John M. Bellama ◽  
Václav Chvalovský
Keyword(s):  
Laser Radiation ◽  
Comparative Study ◽  
Laser Irradiation ◽  
Gas Phase ◽  
Sulfur Hexafluoride ◽  
Phase Interaction ◽  
Cw Co2 Laser ◽  
Co2 Laser Radiation ◽  
Silicon And Germanium ◽  
Derivatives Of

A comparative study of the gas-phase interaction of methyltrichloro derivatives of carbon, silicon and germanium (CH3MCl3 where M = C, Si and Ge) with sulfur hexafluoride either excited by a cw-CO2 laser radiation or under conventional static pyrolytic conditions is reported. 1,1,1-Trichloroethane and methyltrichlorogermane do not react with SF6 under laser irradiation and undergo their decomposition leading to the same products as afforded by heating: CH3CCl3 yields Cl2C=CH2 and HCl, and CH3GeCl3 gives HGeCl3 along with CH4 and C2H2. Mixtures of methyltrichlorosilane and SF6 afford under the both conditions products of the CH3SiCl3 decomposition -CH4, C2H2, HCl and SiCl4 and products of the CH3SiCl3-SF6 reaction -SiF4, SCF2 and CS2. Possible reasons for the different reactivity of CH3MCl3 compounds toward SF6 are briefly discussed. The decompositions of CH3GeCl3 to HGeCl3 offers new way for the preparation of the latter compound.

CW-CO2 laser-induced and SF6-sensitized decomposition of trifluoroacetic acid

1981 ◽  
Vol 46 (11) ◽  
pp. 2854-2859 ◽  
Author(s):  
Josef Pola
Keyword(s):  
Trifluoroacetic Acid ◽  
Surface Reaction ◽  
Reaction Scheme ◽  
Conventional Heating ◽  
Reaction Products ◽  
First Order ◽  
Cw Co2 Laser ◽  
Kinetics Of ◽  
Induced Reaction ◽  
Carbonyl Fluoride

CW-CO2 laser-induced and SF6-sensitized decomposition of trifluoroacetic acid affords reaction products different from those yielded by a conventional heating and offers a new way for decomposition of this compound. The kinetics of the laser-induced reaction is also different, being of a second order and of a first order in SF6. The reaction scheme proposed for the laser-induced process shows .CF2CO2. biradical to be mainly decomposed to carbon monoxide and carbonyl fluoride and implies that the fate of this species during conventional thermal decomposition is controlled by heterogeneous surface reaction.

Di-tert-butyl peroxide decomposition behind shock waves

1976 ◽  
Vol 54 (4) ◽  
pp. 581-585 ◽  
Author(s):  
David K. Lewis
Keyword(s):  
Thermal Decomposition ◽  
Gas Phase ◽  
Single Pulse ◽  
First Order ◽  
Tert Butyl ◽  
First Order Kinetics ◽  
Peroxide Decomposition ◽  
Butyl Peroxide ◽  
Temperature Work ◽  
Lower Temperature

The homogeneous, gas phase thermal decomposition of di-tert-butyl peroxide has been studied in a single pulse shock tube. Samples containing 0.05% to 0.5% reactant in argon were heated to 528–677 K at total pressures of about 1 atm. Acetone and ethane were the only significant products. The reaction obeyed first order kinetics. The Arrhenius parameters, log A (s−1) = 15.33 ± 0.50, Eact (kJ/mol) = 152.3 ± 5.8, are in agreement with the bulk of the earlier reported results of lower temperature work, and with a recently reported result obtained via the very low pressure pyrolysis technique. Indications from some of the earlier work that the A factor may decline at high temperatures are not supported by the present study.

Reactions with half-lives of several years

1964 ◽  
Vol 17 (4) ◽  
pp. 406 ◽  
Author(s):  
GA Bottomley ◽  
GL Nyberg
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Gas Phase ◽  
Virial Coefficient ◽  
Energy Equation ◽  
Second Virial Coefficient ◽  
First Order ◽  
First Order Kinetics ◽  
Reciprocal Temperature ◽  
Temperature Activation

The gas-phase thermal decomposition of dimethyldiazirine, (CH3)2CN2, at very slow rates has been investigated using precision gas-volumetric techniques previously applied to second virial coefficient studies. At 50-70� the first-order kinetics correspond to half-lives about 0.3-3.0 years. The present results, together with data obtained by other workers using conventional apparatus at 124-174�, fit a single log rate-reciprocal temperature activation energy equation.

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