1691-90-3Relevant academic research and scientific papers
Time Resolved Studies of Intermediate Products in the Oxidation of HCFC 141b (CFCl2CH3)and HCFC (CF2ClCH3)
Moers,Hoffmann,Malms,Zellner
, p. 540 - 552 (2007/10/03)
The oxiueauve degradation of HCFC 14Sb (CFCl2CH3) and HCFC 142b (CF2C1CH3) in the presence of NO at T = 293 K and p = 50 mbar has been studied using laser pulse initiation combined with cw laser long path absorption/UF for the detection of OH and NO2. The absolute yield and temporal behaviour of these products have been found to be sensitive indicators for the reaction behaviour of the alkoxy radicals CFCl2CH2O and CF2ClCH2O, respectively. The rate coefficients for the reactions of the alkoxy radicals with O2 were determined to be k(CFCl2CH2O + O2-CFCl2CHO + HO2) = (2.0±1.0)× 10-15 cm3/s and k(CF2ClCH2O + O2→CF2CiCHO + HO2) = (2.5±1.5)× 10-15 cm3/s. Upper limits for the rate coefficients for unimolecular decomposition of the alkoxy radicals by C-C-bond fission of k(CFCl2CH2O + M→CFCl2 + CH2O-rM)≤ 1.0×103 s-1 and k(CF2ClCH2O + M→CF2Cl + CH2OJ-M)≤1.5×103s-1 were derived. We conclude from these data that CFCl2CHO and CF2ClCHO will be formed as the dominant primary carbonyl products in the oxidation of HCFC 141 b and 142b throughout the troposphere. Moreover, the rate coefficients for the reactions of the HCFCs with OH radicals at T = 293 K have been measured. The values k(CFCl2CH3 +OH→CFCl2CH2 + H2O) = (4.6 ±0.8)×10-15 cm3/s and k(CF2ClCH3 + OH→CF2ClCH2 + H2O) = (2.6±0.4)× 10-15cm3/s were obtained. VCH Verlagsgesel/schaft mbH, 1996.
ESR and Optical Evidence on Formation of the Cl(1-)...CCl3(1+) Ion Pair in 3-Methylpentane Matrices ψ-Irradiated at 77 K
Truszkowski, Stanislaw,Ichikawa, Takahisa
, p. 4522 - 4526 (2007/10/02)
The well-known absorption band at 470 nm in CCl4-alkane systems is investigated.The results obtained are as follows: (1) the absorption band due to the radical cation of 5-methyldecane (5MD(1+)) in 5MD-CCl4-3MP systems converts into the 470-nm band. (2) In the conversation, the positive charge of the 5MD(1+) reacts with the unpaired electron of CCl3. radical. (3) CBrCl3 and CCl3F in 3MP glasses produce the absorption bands at 480 nm and 438 nm, respectively, and the nature of these bands is the same with that of the 470-nm band in the all points examined.Results 1 and 2 lead to the formation of CCl(3+) cations.We also obtain evidence on the formation of CCl3(1+) cations from CBrCl3 and CCl2F(1+) cations from CCl3F.It is evident that the band shift observed in the case of CBrCl3 is not attributable to the free ions CCl3(1+) nor to the solvent-separated ion pairs Br(1-)/solvent/CCl3(1+) but the formation of the charge-transfer contact ion pairs Br(1-)...CCl3(1+).Therefore, it is concluded that CCl4 and CCl3F in 3MP produce Cl(1-)...CCl3(1+) and Cl(1-)...CCl2F(1+), respectively.We also obtained the results that CBrF3, CClF3, and CCl2F2 in 3MP glasses yield the corresponding radical anions with absorption bands at 314, 300, and 314 nm, respectively, and that these radical anions are neutralized with the migrating positive charges of the 5MD(1+) formed.
