A Simple Apparatus for Solvent Evaporations I n the course of syntheses using expensive reagents (for example, trans(Pt(pyridine)2NHaC1)Cl from trans-Pt(pyridine)2C12) and relatively high ".~ ~ 7 , boiling solvents (such as water), it may be necessary to concentrate reaction solutions to effect the precipitation of thepmduet. Especially withsemi-micro preparations, the use of s. rotary evaporator is time consuming because of the slow solvent removal and results in appreciable loss of product when the solid is J & J c -_ ~ . removed from the evaporation vessel. Passing compressed air over solutions often results in the introduction of dirt or oil. The apparatus shown in the accompanying figure, consisting of a beaker within a bell jar which is in turn connected to an aspirator, allows unattended solvent evaporation to proceed a t an easily adjustable rate. The size of the heaker containing the solvent may be varied widely (5 ml to 150 ml when using n 15-em high bell jar) to accommodate differently sized preparations. If heating thesolvent gently doesnot alter the product, the beaker and bell may he placed in a heating mantle and the solvent removed more rapidly. Introducing a pipet into the orifice at the tap of increased rate of evaporation. the hell results in 8. highly directional sir flow with co~~comitnnt Atmospherio dust may he excluded by the use of a sintered glass funnel in place of the pipet. (Note: A ring of thin rubber sheet placed between the hell jar and the base allows much cleaner use of the apparatus than using grease for a seal; this is especially handy when filtering prior to the evrtporetion.)
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JOHNE. MARTIN
264
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Journal of Chemical Education
