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Versatile Continuous Laboratory Extractor
I. W. RUDERMAN, Panolyte Division, St. Resir Paper Company, Trenton, N. J.
N CONNECTION with a project carried out in this Isboratory, it was neeessllry to extract a fairly large quantity of various orude materials with organic solvents, such as ether, acetone, methmol, and benzene. It was desired to make the extractions approximately quantitstive. The ordinary size of Soxhlet extractor does not have the capscity required, while large all-glm Soxhlet extraotors me expensive. The extractors of Clarke and Kirner (1) and Tanner (S) were considered not rapid enough and subject to loss of solvent vapor, respectively. An improved extractor constructed from apparatus found in the laboratory pnssessea certain unique ildvantages. As shown in the photogrnph, the ent,ract,orw made up essentially of it dktilling flask, a Biichner funnel, and a water-cooled condenser. The distilling flask, which is s, standard item (Pyrex Catalog 3480), consirts of two parts: s heavy Pymx bottom with a wide ground rim, and a Pyrex dome with a wide ground flange and an opening nt the top. The bottom of the Aask has an inside diamet,er of approximately 165 mm., is 105 mm. deep, and has a capacity of 2000 ml. The dome is preferitbl fitted with a standard taper joint at the top, although the one ,%own is not. 80 constructed. The Bllehner funnel hits an outside diameter of 106 mm. and is supported in the fla3k on B small tripod, which is Pasily made from wire or lass rod. It. is necessary to cut off about 3 om. of the stem a f t h e funnel in order to fit the funnel into the flask. About 300 to 500 ml. of solvent are put into the bottom of the flask. The funnel is fitted with a sheet of filter paper and 100 t,o 200 g r m s of the material to be extracted are added. The two parts of the flask are sealed by a rubber gasket or by B lubricant, unaffeeted hy organic solvents (8). A Thiokol gasket previously extracted with the solvent t o be used makes a good seal. When a gasket is used, the two seotions of the Aask are held to ether by three Hoffman clamps placed around the flange. The #ask is hested by B thermostahically controlled electric hot plat,e nhieh may for safety be covered with an asbestos pad, although no breakage h a been encountered with direct heating. The mt,e of heating is so adjusted that the surface of the material being extracted is at d l times covered with a thin layer of solvent. Under these oonditions there iu B constant flaw of solvent through the material, thereby preventing rest.rieted flow thvough it depression caused by the drip of t,he condensate.
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After the extrxtion is coniplete, the funnel and tripod are removed, a distilling head is connected to the flask, and the condenser is wrranged for distillation to remove the solvent. When $1 the solvent, has been removed, the apparatus is dismantled, and the hottam of the Aaqk is placed in an oven or desiccator in order to dry the extract. The large surface presented by the bottom of the flask facilitates drying, particularly with viscous liquid ext,rac.ts.
When used in the organic chemical laboratory, the extractor pofisesses the unique advantage of permitting the following sequence of operations to be carried out, in the same apparatus: the crude material is collected hy filtration in the Biiohner funnel: the funnel is transferred to the extreetion flask and the crude material is extracted; and the extrmt Is freed from solvent and dried. Such continuity pmvents lo- of material, save8 time, and makes possible approximate quantitative work. LIIERATURE CITED
(1) Clarke and Kirner. Ow. Swnthesen. 2,49 (1922). (2) Meloohe and Fredriok. J. Am. Cham. Soc.. 54, 32&1 (1932). (3) Tanner. IND. ENG.CHES..ANAL.ED..4.397 (1982).
Support for Flasks on Steam and W a t e r Baths
LORNE FORD, Research Laboratory, Tho Canadian Fishing Co., Ltd., Vancouver, British Columbis bottom half of round flasks and only t,he flat bottom of Erlenmeyer flasks to he exposed t,o the steam, unless the flasks are supported by a buret clamp or Some other means. A simple at.taehment, t,o the cdvers is shown in the accompmylng illustration. I t eonsists of two st.rips of sheet metal bent into a U-shape as shown, and soldered to the lower part of the hattom surface of the concentric ring, having a n insidediameter larger than that of the flask to he supported. The two Pshaped strips are soldered to the ring at right angles to each other, so that they iorm a rack to support the flask. The depth of the sides of the U-shaped strips is such that when the flask is in position the next smallest ring or set of rings may be dropped into place over the neok of the flask and will fit closely around t,h< ? narrow upper p ortion of the flask and also to the other rings. The greater poi.tion of the flask is enclosed by the steam bath . , . . ^ a u t =..=,..dy to the steam, without the ctnd cover8 and is ^-,,uo=y necessity of out.side supports. The covers serve as a seal around the upper portion of the flask and no ocher packing is required to stop escape of steam from the system.
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refluxing and distillation of solvents in flasks on steam baths are often rather slow, but can be considerably speeded up by lowering the flasks into the bath so that a greater p a t of the surface is exposed to the steam. The concentric rings which ordinarily form the covers of s t e m baths allow no more than t,he
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