A Semi-Micro Hot Filtration Apparatus Very often it is necessary to filter insolttble imporit,ies ant of a aolut,ion from which an organic compound is being recrystallized. By dissolving bhe compoltnd in a minimum n m o ~ m t of boiling solvent and then filtering, the irnpnribies can be removed. The problem of crystallifiat,ion in the fiker funnel is a common occurence; this resdts in a decreased yield of porified compoond and in tho case of small quantit,ies of material (less than 100 mg of compound and 5 ml of solvent) very large loss of compormd may remlt. Rapid v a e w m filtration is the answer to the ~ r o b l e mhut most vacnnm filters have a relativelv " laree swfaco area to which the solut,ion adheres resulting in loss of purified material. We have devised sn inexpensive vacrlum filtration apparatus which comhines the features of small surface area in the filter ( A ) , rapid passage of solution thrangh the filt,er and concentration of filtrate in a relatively small area ( R ) . The 15 X 125 mm side-arm test tube (C) is fitted with a no. 4 cork ( D )bored to fit 7-mm glass tuhingsnagly. Theglass tubing is fiared a t the upper end (mouth) and drawn ant a t the other as to reach approximately 1-2 cm from the bottom of the side-arm test tube. A small piece of glass wool or cotton is tamped into the constriction of the tubing. By applying snction to the side-arm with a water aspiretor and transferring the hot solution with an eye dropper to the month of the glass tubing, filtrnbian is ufiecled rapidly and efficiently. I~cFIARDW. K o c o ~
5 16
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Journal of Chemical Education
