scholarly journals Rate Constants and Activation Energies for Gas‐Phase Reactions of Three Cyclic Volatile Methyl Siloxanes with the Hydroxyl Radical

2015 ◽  
Vol 47 (7) ◽  
pp. 420-428 ◽  
Author(s):  
Andreas Safron ◽  
Michael Strandell ◽  
Amelie Kierkegaard ◽  
Matthew Macleod
1958 ◽  
Vol 36 (11) ◽  
pp. 1493-1500 ◽  
Author(s):  
G. Giacometti ◽  
E. W. R. Steacie

The rate constants and activation energies for the reactions of C3F7 radicals with methane and ethane have been measured by photolyzing mixtures of C3F7COC3F7 and hydrocarbon with 3130 Å light. Photolysis of mixtures of the ketone, methane, and deuterium has been used to check previous measurements on the reaction of C3F7 and deuterium.


The work described in this and the following paper is a continuation of that in parts I and II, devoted to elucidation of the mechanism of the reactions of methylene with chloroalkanes, with particular reference to the reactivities of singlet and triplet methylene in abstraction and insertion processes. The products of the reaction between methylene, prepared by the photolysis of ketene, and 1-chloropropane have been identified and estimated and their dependence on reactant pressures, photolysing wavelength and presence of foreign gases (oxygen and carbon mon­oxide) has been investigated. Both insertion and abstraction mechanisms contribute significantly to the over-all reaction, insertion being relatively much more important than with chloroethane. This type of process appears to be confined to singlet methylene. If, as seems likely, there is no insertion into C—Cl bonds under our conditions (see part IV), insertion into C2—H and C3—H bonds occurs in statistical ratio, approximately. On the other hand, the chlorine substituent reduces the probability of insertion into C—H bonds in its vicinity. As in the chloroethane system, both species of methylene show a high degree of selectivity in their abstraction reactions. We find that k S Cl / k S H >7.7, k T Cl / k T H < 0.14, where the k ’s are rate constants for abstraction, and the super- and subscripts indicate the species of methylene and the type of atom abstracted, respectively. Triplet methylene is discriminating in hydrogen abstraction from 1-C 3 H 7 Cl, the overall rates for atoms attached to C1, C2, C3 being in the ratios 2.63:1:0.


1981 ◽  
Vol 59 (11) ◽  
pp. 1615-1621 ◽  
Author(s):  
Scott D. Tanner ◽  
Gervase I. Mackay ◽  
Diethard K. Bohme

Flowing afterglow measurements are reported which provide rate constants and product identifications at 298 ± 2 K for the gas-phase reactions of OH− with CH3OH, C2H5OH, CH3OCH3, CH2O, CH3CHO, CH3COCH3, CH2CO, HCOOH, HCOOCH3, CH2=C=CH2, CH3—C≡CH, and C6H5CH3. The main channels observed were proton transfer and solvation of the OH−. Hydration with one molecule of H2O was observed either to reduce the rate slightly and lead to products which are the hydrated analogues of the "nude" reaction, or to stop the reaction completely, k ≤ 10−12 cm3 molecule−1 s−1. The reaction of OH−•H2O with CH3—C≡CH showed an uncertain intermediate behaviour.


2003 ◽  
Vol 107 (34) ◽  
pp. 6603-6608 ◽  
Author(s):  
Woojin Lee ◽  
Philip S. Stevens ◽  
Ronald A. Hites

1982 ◽  
Vol 13 (8) ◽  
Author(s):  
R. ATKINSON ◽  
S. M. ASCHMANN ◽  
A. M. WINER ◽  
J. N. JUN. PITTS

Sign in / Sign up

Export Citation Format

Share Document