634-66-2Relevant articles and documents
Photoisomerisation of bicyclo[4.2.0]octadienes to tricyclo[4.2.0.02,5] octenes: Application to the synthesis of [n]ladderanes
Warrener,Pitt,Nunn,Kennard
, p. 621 - 624 (1994)
A new approach for the extension of [n]ladderanes is described which involves formation of an end-fused bicyclo[4.2.0]octadiene and its photoisomerisation to the related tricyclo[4.2.0.02,5] octene as the ladderane extension step. The protocol is illustrated with the synthesis of [3]ladderane (9) from an unsubstituted cyclobutene and nor[5]ladderane (13) from an ester activated cyclobutene. The exo-stereochemistry of (13) is confirmed by reference to intermediate (23) for which a single crystal X-Ray structure analysis was obtained.
Preparation method for 3,5,-dichloro-2,4,-difluoroaniline
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, (2017/03/08)
The invention relates to the field of organic synthesis, specifically to a preparation method for 3,5,-dichloro-2,4,-difluoroaniline and application thereof. The preparation method for 3,5,-dichloro-2,4,-difluoroaniline provided by the invention comprises the following steps: 1) nitration reaction; 2) reduction reaction; 3) diazotization reaction; 4) nitration reaction; 5) fluorination reaction; and 6) reduction reaction. The preparation method for 3,5,-dichloro-2,4,-difluoroaniline provided by the invention has the following beneficial effects: 1) the method has mild reaction conditions, is stable and controllable, has less active sites, is insusceptible to side reaction, and has good yield and quality in the whole line; and 2) raw materials are cheap and easily available, so cost can be effectively reduced, and energy is saved; meanwhile, the use of chlorine gas is avoided, so the method is environment-friendly.
Identification of surrogate compounds for the emission of PCDD/F (I-TEQ value) and evaluation of their on-line realtime detectability in flue gases of waste incineration plants by REMPI-TOFMS mass spectrometry
Blumenstock,Zimmermann,Schramm,Kettrup
, p. 507 - 518 (2007/10/03)
Correlations between products of incomplete combustion (PIC), e.g., chloroaromatic compounds, can be used to characterise the emissions from combustion processes, like municipal or hazardous waste incineration. A possible application of such relationships may be the on-line real-time monitoring of a characteristic surrogate, e.g., with Resonance-Enhanced Multiphoton Ionization-Time-of-Flight Mass Spectrometry (REMPI-TOFMS). In this paper, we report the relationships of homologues and individual congeners of chlorinated benzenes (PCBz), dibenzo-p-dioxins (PCDD), dibenzofurans (PCDF) and phenols (PCPh) to the International Toxicity Equivalent (I-TEQ) of the PCDD/F (I-TEQ value) in the flue gas and stack gas of a 22 MW hazardous waste incinerator (HWI). As the REMPI detection sensitivity is decreasing with the increase of the degree of chlorination, this study focuses on the lower chlorinated species of the compounds mentioned above. Lower chlorinated species, e.g., chlorobenzene (MCBz), 1,4-dichlorobenzene, 2,4,6-trichlorodibenzofuran or 2,4-dichlorophenol, were identified as I-TEQ surrogates in the flue gas. In contrast to the higher chlorinated phenols, the lower chlorinated phenols (degree of chlorination 4) were not reliable as surrogates in the stack gas. The identified surrogates are evaluated in terms of their detectability by REMPI-TOFMS laser mass spectrometry. The outcome is that MCBz is the best suited surrogate for (indirect) on-line measuring of the I-TEQ value in the flue gas by REMPI-TOFMS. The correlation coefficient r of the MCBz concentration to the I-TEQ in the flue gas was 0.85.
Reactions of 2,4,6-trichlorophenol on model fly ash: Oxidation to CO and CO2, condensation to PCDD/F and conversion into related compounds
Hell,Stieglitz,Altwicker,Addink,Will
, p. 697 - 702 (2007/10/03)
Thermal treatment of 2,4,6-trichlorophenol on a magnesium silicate-based model fly ash in the temperature range between 250°C and 400°C leads predominantly to carbon monoxide and carbon dioxide. The fraction of 2,4,6-trichlorophenol which is oxidized to CO and CO2 increases from 3% at 250°C to 75% at 400°C. Further products are polychlorinated benzenes, dibenzo-p-dioxins, dibenzofurans and phenols. The homologue and isomer patterns of the chlorobenzenes suggest chlorination in the ipso-position of the trichlorophenol. The formation of PCDD from 2,4,6-trichlorophenol and 2,3,4,6-tetrachlorophenol on municipal solid waste incinerator fly ashes and model fly ash were compared and the reaction order calculated.