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实验室中常用的某些金属,如镁、铝、锌及铁等在空气中都会与氧或水反应生成相应的氧化物而复盖在金属表面上。这些不溶(特别是对有机溶剂更难)的氧化物常常使这些金属的有机反应不能很好进行,因此反应前要求对金属先进行活化。如在进行氯化物的Grignard反应,具有一定空间障碍的酮的Refomatsky反应,铁催化芳烃某些反应时,虽然文献中通常都认为可用适当的稀酸来活化金属,但操作不详。我们发现操作的关键是防止已被活化的(即已被洗去表面氧化物的)金属表面再被氧化,因此必须尽快地完成活化这个过程,以保证活化效果。我们认为对条状金属活化过程在普通分液漏斗中进行,对粉状物则在砂芯漏斗中进行是方便的。
Some metals commonly used in laboratories, such as magnesium, aluminum, zinc and iron, react with oxygen or water in the air to form corresponding oxides and cover the metal surface. These insoluble (especially harder for organic solvents) oxides often make the organic reactions of these metals poorly performed and therefore require the metal to be activated prior to the reaction. Such as the Grignard reaction of chlorides, the Refomatsky reaction of ketones with certain steric hindrances, and the iron-catalyzed reactions of aromatic hydrocarbons, although it is generally accepted in the literature that metals can be activated with the appropriate dilute acids, the operation is unknown. We found that the key to the operation is to prevent the metal surface that has been activated (ie, the surface oxide that has been washed away) from being oxidized. Therefore, the activation must be completed as soon as possible so as to ensure the activation effect. We believe that the activation of the strip metal is carried out in a conventional separatory funnel and that it is convenient for the powder to be carried in a sand funnel.