Yuan Tao, Marshall William D
Department of Food Science and Agricultural Chemistry, McGill, Ste-Anne-de-Bellevue, Québec, Canada.
J Environ Monit. 2002 Jun;4(3):452-7. doi: 10.1039/b200652a.
A stream of substrate pentachlorophenol [PCP, 5 mg min(-1) in water-methanol (1 + 4, v/v)] was merged with 1.5 ml min(-1) of supercritical carbon dioxide (scCO2) and delivered to a reactor column (25 cm x 1 cm) of zero-valent palladium-magnesium mixture. The resulting dechlorinations, although very efficient, were not quantitative. For continuous operation at 400 degrees C for 6 h, phenol was the principal product, with lesser quantities of methylated products and only traces of chlorinated products (principally monochlorinated species). PCP deoxygenation was not observed and ring methylation was decreased relative to analogous reactions in hydroxylic organic solvent. With time, the reactor column slowly lost dechlorination activity. Reducing the loading of Pd0 on Mg0 from 2% to 1% (w/w) apparently did not change the course of the reaction; however, the dechlorination capacity was decreased correspondingly. None the less, over 6 h or 5 h of continued operation, the dechlorination efficiency was 0.995 for the 2% (w/w) loading of Pd0 on Mg0 and 0.984 for the 1% (w/w) loading.
一股底物五氯苯酚[PCP，在水 - 甲醇（1 + 4，v/v）中为5 mg min⁻¹]与1.5 ml min⁻¹的超临界二氧化碳（scCO₂）合并，并输送至零价钯 - 镁混合物的反应器柱（25 cm×1 cm）。所产生的脱氯反应虽然非常高效，但并非定量反应。在400℃下连续运行6小时，苯酚是主要产物，甲基化产物的量较少，且仅含有痕量的氯化产物（主要是一氯代物种）。未观察到PCP的脱氧反应，并且相对于在羟基有机溶剂中的类似反应，环甲基化减少。随着时间的推移，反应器柱的脱氯活性逐渐缓慢丧失。将Mg₀上Pd⁰的负载量从2%降至1%（w/w）显然并未改变反应进程；然而，脱氯能力相应降低。尽管如此，在持续运行6小时或5小时的过程中，对于Mg₀上2%（w/w）负载量的Pd⁰，脱氯效率为0.995，对于1%（w/w）负载量的Pd⁰，脱氯效率为0.984。
