Gas phase photolysis of ethyl bromide at 253. 7 nm

Journal Article · Thu Oct 05 04:00:00 EDT 1978 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j100509a009· OSTI ID:6594107

Frank, A J; Hanrahan, R J

The photolysis of ethyl bromide was studied at 100 torr and 23/sup 0/C using 253.7-nm radiation. In the pure system between 60 and 90 s at an absorbed light intensity of 8.3 x 10/sup 13/ quanta/cm/sup 3/ s the major products and their respective quantum yields are as follows: hydrogen bromide, 0.26; ethane, 0.40; ethylene, 0.028; 1,1-dibromoethane, 0.102; 1,2-dibromoethane, 0.0092; vinyl bromide, 0.009; 1,1,2-tribromoethane, 0.0027; methane, 0.00052; and methyl bromide, 0.00091. When 5 mol % oxygen is added, the quantum yields in this time period become the following: hydrogen bromide, 0.47; ethane, 0.00032; ethylene, 0.0081; 1,1-dibromoethane, 0.0040; 1,2-dibromoethane, 0.022; vinyl bromide, 0; 1,1,2-tribromoethane, 0; methane, 0.0001; and methyl bromide, 0.091. Bromine is also formed with a quantum yield of 0.22. At long photolysis times the HBr and C/sub 2/H/sub 4/ go into a stationary state, and the main photolysis products are C/sub 2/H/sub 6/ and 1,1-C/sub 2/H/sub 4/Br/sub 2/ with quantum yields of 0.24 and 0.17, respectively. The behavior of the system is interpreted based on a model involving C--Br rupture as the main primary process (phi = 0.8) with a substantial contribution of HBr elimination (phi = 0.2). Primary C/sub 2/H/sub 5/ . and Br . fragments abstract hydrogen from the substrate to produce mainly the 1-C/sub 2/H/sub 4/Br. radical. Net product formation involves reaction of radical species with Br/sub 2/ (present at low, steady-state concentration <10/sup -5/ M), Br. atoms, or HBr. The dynamic behavior of the system was investigated by computer simulation and compared with experimental results. 2 tables, 7 figures.

• Research Organization: Univ. of Florida, Gainesville
• OSTI ID: 6594107
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 82:20; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
ALKANES
ALKENES
BROMINATED ALIPHATIC HYDROCARBONS
BROMINE
CHEMICAL REACTION KINETICS
CHEMICAL REACTION YIELD
CHEMICAL REACTIONS
CRYOGENIC FLUIDS
DECOMPOSITION
ELEMENTS
ETHANE
ETHYLENE
FLUIDS
GASES
HALOGENATED ALIPHATIC HYDROCARBONS
HALOGENS
HYDROBROMIC ACID
HYDROCARBONS
HYDROGEN COMPOUNDS
INORGANIC ACIDS
KINETICS
LOW PRESSURE
MEDIUM TEMPERATURE
METHANE
METHYL BROMIDE
NONMETALS
ORGANIC BROMINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
OXYGEN
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
PRESSURE DEPENDENCE
RADICALS
REACTION INTERMEDIATES
REACTION KINETICS
TEMPERATURE DEPENDENCE
TIME DEPENDENCE
YIELDS