Filtration of air-sensitive compounds

Filtration of Air-Sensitive Compounds I t is sometimes desireable to filter s reaction mixture without rrpoaini: it to air. WP have designrd and used a very convenient method for filtration of low-boiling rolvents thigh vapor pressure, such as dirrhylether or pentane without nitrogen or helium pres~

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The equipment consists of a bent glass tuhe with one end flattened (a) and with filter paper wrapped on it to keep a check on solid particles (see figure). The tuhe is passed through two robber corks as shown. The corks should he of a size that fits tightly in the necks of two flasks A and B. Bores of the corks should allow an easy movement of the tuhe without leakage. A calcium chloride guard tube is fitted onto the flask B. The end a of the tuhe is slowly dipped into the reaction mixture. A mild heating of flask A with a hot air blower accelerates the filtration, hut prolonged heating is not recommended. The vapor pressure of the solvent in flask A pushes the filtrate towards flask B. The solvent vapors blanket the filtrate in flask B, and there is absolutely no chance of contact with air. This method is equally valid and effective, no matter what the product is in the residue or the filtrate. Saqib All, M. Mazhar, and Inhad A. Zla Quaid-i-Azam University Islamabad, Pakistan

902

Journal of Chemical Education

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