Kinetic and thermochemical study of the silyl + hydrogen bromide .dblharw. silane + bromine atom and silyl + hydrogen iodide .dblharw. silane + iodine atom equilibria

1991 ◽  
Vol 95 (4) ◽  
pp. 1658-1664 ◽  
Author(s):  
J. A. Seetula ◽  
Y. Feng ◽  
D. Gutman ◽  
P. W. Seakins ◽  
M. J. Pilling
Keyword(s):  
Iodine Atom ◽  
Hydrogen Bromide ◽  
Bromine Atom ◽  
Hydrogen Iodide ◽  
Thermochemical Study

Photodissociation of superexcited states of hydrogen iodide: A photofragment imaging study using resonant multiphoton excitation at 13.39 and 15.59 eV

2001 ◽  
Vol 79 (2-3) ◽  
pp. 211-227 ◽  
Author(s):  
H -P Loock ◽  
B LG Bakker ◽  
D H Parker
Keyword(s):  
Excited States ◽  
Iodine Atom ◽  
Imaging Study ◽  
Local Interaction ◽  
Hydrogen Iodide ◽  
Multiphoton Excitation ◽  
Velocity Mapping ◽  
Weakly Bound ◽  
Excitation Scheme ◽  
Photon Excitation

Jet-cooled HI has been excited using a resonant three-photon excitation scheme to energies corresponding to 13.39 and 15.59 eV. Analysis of velocity mapping images of the iodine atom fragments allowed the identification of the HI excited states at these energies as the (4Σ–1/2) 6p superexcited state and the repulsive 4Σ–1/2 state of HI+, respectively. Following excitation at 13.39 eV, we observe formation of iodine atomic fragments through the H(2S) + I[(3PJ) 6p] (J = 0, 1, 2) fragment channels, as well as through the H(2S) + I[(1D2) 6p] channel. This observation is explained by extensive nonadiabatic interactions between the (4Σ–1/2) 6p state with the repulsive (4Π1/2) 6p state and the weakly bound (A 2Σ+) 6p state. In support for this proposed dissociation mechanism excitation of the corresponding ionic 4Σ–1/2 state at 15.59 eV also results in formation of comparable quantities of I+ in its 1D2, 3P0,1, and 3P2 levels indicating again extensive nonadiabatic interactions with other repulsive curves. A similar mechanism based on the local interaction of the 4Σ–1/2 state with the A 2Σ+ and the 4Π1/2 state is proposed. PACS Nos.: 82.50F, 32.80R

The relative rates of bromination of cyclohexane and cyclopentane with molecular bromine. Comparison of the reactions in solution and in vapor phase

1981 ◽  
Vol 59 (9) ◽  
pp. 1368-1374 ◽  
Author(s):  
Dennis D. Tanner ◽  
Tomoki C-S. Ruo ◽  
Hideki Takiguchi ◽  
Andre Guillaume
Keyword(s):  
Vapor Phase ◽  
Hydrogen Bromide ◽  
Bromine Atom ◽  
Relative Rate ◽  
Solution Phase ◽  
Molecular Bromine ◽  
Transfer Rates ◽  
Relative Rate Constants ◽  
Halogenated Alkanes ◽  
Relative Transfer

The relative rates of transfer of the cyclopentyl radical with molecular bromine and hydrogen bromide (k2′/k−1′) and with hydrogen tribromide and hydrogen bromide (k3′/k−1′) have been determined. The relative transfer rates are compared with the analogous values previously reported for the reactions of cyclohexyl radicals (k2/k−1 and k3/k−1). Utilizing the values of k2′/k−1 and k2/k−1 the competitive vapor phase rates of bromine atom abstraction of hydrogen from the two substrates could be obtained. An expression using a combination of the five sets of relative rate constants was used to determine the effect of competitive cage reversal which occurs in the solution phase bromination of the two substrate radicals with caged hydrogen bromide. For two structurally similar radicals, cage reversal (internal return) was found to affect the relative rates of bromination by 30%, while the relative transfer rates, although differing each by a factor of two, fortuitously nearly cancel each other's effect.The effect of both internal and external reversal reactions on the relative rates of bromination of structurally dissimilar substrates, halogenated alkanes and their parent hydrocarbons, is discussed.

The thermal decomposition of n-propyl bromide

1968 ◽  
Vol 21 (4) ◽  
pp. 973 ◽  
Author(s):  
JTD Cross ◽  
VR Stimson
Keyword(s):  
Thermal Decomposition ◽  
Rate Constant ◽  
Hydrogen Bromide ◽  
Bromine Atom ◽  
Order Reaction ◽  
Chain Mechanism ◽  
Initial Concentration ◽  
First Order ◽  
Reaction Proceeds ◽  
Atom Chain

Mechanisms already proposed or formally possible for the decomposition of n-propyl bromide as a 312-order reaction are shown to be unsatisfactory, and the reaction has been reinvestigated. Two reactions occur simultaneously: (a) a first-order reaction identifiable with the maximally inhibited reaction and presumably molecular; (b) a reaction second order in the initial concentration and somewhat autocatalysed as the reaction proceeds. The rate constant is given by k2 == 1018.1exp(-49300/RT)sec-1ml mole-1 Reaction (b) is catalysed by hydrogen bromide and inhibited by propene, and a bromine atom chain mechanism with hydrogen bromide catalysed initiation is proposed. Bromine-catalysed decomposition has also been studied. The mechanism of the inhibition is discussed.

Sign in / Sign up

Export Citation Format

Share Document