Direct measurement of methylene removal rates by species containing the OH functional group

Staker, Warren S.; King, Keith D.; Gutsche, Greg J.; Lawrance, Warren D.

doi:10.1039/ft9918702421

Cited by 25 publications

(23 citation statements)

References 10 publications

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“…[13][14][15][16] We give here a brief overview and provide details relevant to the temperature dependence experiments. The same stainless steel reaction cell is used for the high-temperature work as was used for the ambient temperature studies.…”

Section: Methodsmentioning

confidence: 99%

Temperature Dependences of Singlet Methylene Removal Rates

and¹,

Lawrance²,

and³

et al. 1996

J. Phys. Chem.

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The technique of laser flash photolysis/laser absorption has been used to obtain absolute removal rate constants for singlet methylene, 1 CH 2 (a ˜1A 1 ), in the temperature range 298-462 K. The temperature dependences of the removal rate constants for N 2 , CH 4 , C 2 H 4 , C 2 H 6 , H 2 O, H 2 CO, CH 2 CO, CH 3 F, C 2 F 6 , and CH 3 OH were measured and the Arrhenius parameters determined. For the reacting species, CH 4 , C 2 H 4 , C 2 H 6 , H 2 O, H 2 CO, CH 2 CO, CH 3 F, and CH 3 OH, the rate constants exhibit negative temperature dependences with activation energies covering the range -0.7 ( 0.7 kJ mol -1 for CH 3 F to -3.5 ( 1.0 kJ mol -1 for CH 3 OH. In contrast, positive temperature dependences are observed for the nonreacting species, N 2 and C 2 F 6 , with activation energies of 1.8 ( 0.9 and 1.6 ( 2.0 kJ mol -1 , respectively. Good agreement was obtained with previously reported measurements for the N 2 , CH 4 , CH 2 CO, C 2 H 4 , and C 2 H 6 temperature dependences. For the nonreacting species, comparison is made with theoretical predicted temperature dependences for collision-induced intersystem crossing from 1 CH 2 (a ˜1A 1 ) to 3 CH 2 (X ˜3B 1 ).

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Section: Methodsmentioning

confidence: 99%

Temperature Dependences of Singlet Methylene Removal Rates

and¹,

Lawrance²,

and³

et al. 1996

J. Phys. Chem.

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“…The intercept corresponds to the measured pseudo-first-order removal rate constant for the concentrations of CHzCO and N2 in the reaction mixture [14,17,18]. The errors quoted correspond to 2u statistical errors from the weighted linear least-squares analysis plus estimated errors due to uncertainties in flow rates and total pressure.…”

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confidence: 99%

“…27, 623-626 (1995) Pseudo-first-order decays are measured as a function of reactant pressure. The pseudo-first-order rate constants are extracted from the experimental decays as described previously [14,17,18]. A plot of the pseudo-first-order rate constants vs. reactant pressure yields a straight line (Fig.…”

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Comparison of singlet methylene removal rates by group IV hydrides

Gutsche

Lawrance

Staker

et al. 1995

Int J of Chemical Kinetics

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The technique of laser flash photolysisflaser absorption has been used to obtain an absolute removal rate constant of (3.85 2 0.18) X cm3 molecule-' s-l for singlet methylene, lCHz (glA1), with germane (Ge&) at ambient temperature. The removal rate constant is compared with the values for methane (CH4) and silane (SiH4) which have been determined previously. 0 1995 John Wiley & Sons, Inc.The simplest carbene, methylene (CHz), possesses a distinctive chemistry, playing significant roles in such reaction systems as flames, combustion, and planetary atmospheres. Carbenes form an important class of reactive intermediates in organic chemistry. The fundamental importance of CH2 has resulted in a significant literature devoted to this species in recent years [l]. An increased interest in the gas-phase kinetic studies of CH2 has occurred, largely due to the case with which the metastable singlet state (5lA1, abbreviated lCH2) may be observed by techniques such as laserinduced fluorescence (LIF) and laser resonant absorption (LRA). Since the first study [2] of lCH2 reaction rates using a direct method, several groups have measured bimolecular removal rate constants for lCH2 with a wide range of organic and inorganic molecules using laser-based methods 13-171.While removal rate constants have been measured for lCH2 reacting with a range of organic compounds, there has yet to be any detailed studies of reactions with organometallics. In this study we have used the technique of laser flash photolysisfiaser absorption to determine the absolute rate constant for the removal of lCH2 by germane (GeH4) at ambient temperature (298 * 2 K), apparently for the first time. The removal rate constant is compared with those measured previously for lCH2 with methane (CH4) and silane (SiH4).

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“…This effect has also been seen in our previous kinetic studies of singlet CH 2 and SiH 2 . [16][17][18][21][22][23][24][25][26][27][28] We have shown previously that the rate constants are independent of photolysis wavelength, indicating that vibrational relaxation is not an issue in this system. 9 The rate constants reported here were obtained with total cell pressures in the range 10-200 Torr.…”

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Rate constants for the gas-phase reactions of germylene with CH3OCH3, CH3OH, CD3OD and D2O at ambient temperature

Alexander

King

Lawrance

2003

Phys. Chem. Chem. Phys.

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Gas-phase rate constants for the reactions of germylene, GeH 2 , with dimethylether (CH 3 OCH 3 ), methanol (CH 3 OH), deuterated methanol (CD 3 OD), and deuterated water (D 2 O), have been determined at ambient temperature (295 K) and total pressures over the range 10-200 Torr of the bath gas SF 6 . The second-order rate constants are pressure dependent up to the maximum pressures investigated. The behaviour of GeH 2 with these reactants is very similar to the behaviour observed for silylene, SiH 2 . Over the same pressure range the GeH 2 reaction rate constants are smaller than those observed for SiH 2 .

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Direct measurement of methylene removal rates by species containing the OH functional group

Cited by 25 publications

References 10 publications

Temperature Dependences of Singlet Methylene Removal Rates

Temperature Dependences of Singlet Methylene Removal Rates

Comparison of singlet methylene removal rates by group IV hydrides

Rate constants for the gas-phase reactions of germylene with CH3OCH3, CH3OH, CD3OD and D2O at ambient temperature

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