6.1. Johnson
Montana Stote Univers~ty Bozeman, Montana 59715
Techniques for Internal Distillation-Condensation
The well-known and much-used Soxhlet (1)extraction apparatus and its Bailey-Walker modification (8) are based essentially on internal distillationcondensation techniques. We have developed new modifications for semi-micro collection of pure substances (3-5) and macro extraction (6, 7) which have the advantages of simplicity and ease of construction. Figure 1 illustrates, for the semi-micro scale, how a volatile organic compound such as alcohol may be distilled, condensed and caught in a small glass cup, after drying wit,h CaO, with almost negligible loss. The various parts of t,he assembly are nurnhered in F i ~ n r e1 and are described below. Part 1 contains a mixture of 0.5-1.0 ml of alcohol, Ca(OH),, and CaO. It is assumed here the alcohol contained H 2 0 and came from a previous saponification of an ester whose identity is sought via its alcohol constituent radical. Part 2 is a narrow wad of glass wool, recently over1 dried, to prevent spattering into upper reaches of Part 7. Part 3 is a glass cup obtained by cutting off the bottom part of a narrow Pyrex test tube, and Part 4 is a 2-mmdiam Pyrex glass rod sealed into the hottom of the cup. Its other end is heat-bent into a hook. Before use cup assernhly is oven dried. Part 6 is a Pyrex test tube about 8 in. in length with a
diameter such that it will slip easily into Part 7. Enough space should exist between Parts 6 and 9 so condensed alcohol drops will not bridge this spaee. Part 6 has a conical bottom and a sealed-in Pyrex
& -3
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Figure 1. Semi-micro internal distillation condensation opporotur.
Figvre 2. Large x o l e internoi distillation condensation fmt solvent extraction opporotus.
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hooked rod. By these means co~idensateis direct,ed to the glass cup. The hooked rods engage one another. Part 7 is a 10- X 1-in. Pyrex test tube, and Part 8 is a thick rubber band cut from a suitable rubber tube of in. thickness. It supports tube 6 in tuhe 7. I t gives adjustability to position in tube 7. Parts S and 6 should be oven dried to remove as much adsorbed water as possible and used immediately when at room temperature. Room temperature water is poured into Part 6. The cup is attached and this assembly hung in Part 7. To vaporize the ala,hol gent,le heat is applied at the bottom of Part 7. Actual boiling is avoided, but applying flame to that part below the cup may be necessary. The condensate collects in the cup. Overheating causes loss of alcohol and boiling of alcohol in the cup. The drying of the alcohol is usually done in Part 7 by adding enough recently ignited CaO to make a paste. This mixture must be refluxed 6 8 hr, using an effective reflux condenser. The cup containing alcohol may now be stored in a glass-stoppered container just large enough to receive it. Figure 2 shows how pouud lots of dried plant or animal materials may be fat-solvent extracted conveniently with very little attention. The following gives t,hemechanics of extraction and apparatus parts. Part 1 is a long hollow metal cylinder. It can be made from 2-lb coffee cans from which top covers and bottoms have been removed and soldered together. The bott,om of one is left intact. Part 2 is a tripod, and Part 3 is the extractor assembly consisting of an inverted bottomless bottle which carries a one hole cork (Part 4), an invert,edglass test tube (Part 6),and an inside siphon
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tube (Part. 6), which extends through the cork. The tube rests on some loosely packed cotton. Part 7 is a cylindrical metal condensing uuit with conical bottom with a f i e d metallic r a t e r inlet (Part 8 ) and outlet (Part Q), plus metal shoulder flange (Part 10) which should encircle Part 7 to support it in the cylinder. Part 18 is the solvent which evaporates to form condensate on Part 7, which in turn fills the extractor assembly to the siphon level. Pad 13 is the space for the sample. The ent,ire assembly can rest on all electric heater with variable heat control. With judicious heating and a su&ciently cold water flow t,hrough Part 7, cool condensate will keep solvent in Part 3 from boiling. Because the assembly is completely made up of removable parts cleaning is no problem. Recovery of the solvent is also possible by removing the extracted sample, catching solvent in empty Part 3, and removing condensed solvent before siphoning occurs; or a small cork plug may be inserted in the tuhe which will permit Part S to fill completely. Literature Cited (1) BOXBLET, i'Extt~mtio~~ S p p m a t i d (65lh ed.), Model 4'JX7A, A. H. Thamns Co., Philsdelphiil, Pa., 1965, p. 497. (2) BAILEI--WALKER, "Extra~tionApparatus" (65th ed.), Model 51144.8, A. 11. Thomas Cu.. Philadel~his, Pa.. 1965,
George Thiene, Leipzig, Germany, 1925, 6
