Organic 2 Review Problem 39

Organic 2 Review Problem 39 - M ETHODS A ND M ANIPULATION...

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METHODS AND MANIPULATION 23 filter-paper (particularly when a Buchner funnel is used), and thus cannot easily be eliminated. Alternatively the suspension may be easily held back by the filter-paper in the Buchner funnel, but then may rapidly block up the pores of the filter and so arrest filtration almost completely, with the result that crystallisation occurs in the cooling solution while it is still in the Buchner funnel, i.e., before filtration is complete. Both these difficulties can usually be overcome by boiling the solution with a small quantity of animal charcoal. The latter readily adsorbs such fine suspensions, and the hot solution can then be filtered clearly and rapidly through the Buchner funnel. Sublimation. This process is occasionally used for the purification of solid organic compounds. Its use is necessarily limited to those compounds which on heating pass readily and directly from the solid to the vapour state, with a subsequent ready reversal of this process when the vapour is cooled. A simple
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This note was uploaded on 09/19/2011 for the course CHM 2211 taught by Professor Castalleano during the Fall '06 term at University of Florida.

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