I,VDUSTRIAL AND ENGINEERING CHEMISTRY
April, 1927
53 5
in the cork of this flask is passed a half-inch tube bent to connect with the condenser tube. This greatly simplifies the apparatus, as anyone can bend this tube, and tubes with stopcocks are regularly marketed by any apparatus house. In so far as this modification has been used it has proved as satisfactory as that illustrated. In the writer’s opinion an extractor of this type could be constructed from metal such as copper, zinc, galvanized iron, etc., and made even more satisfactory than the one illustrated.
3-It does not siphon; therefore the entire drug is constantly in contact with the solvent. 4-The receiving flask may be small regardless of the amount of drug used or size of percolator. 5-Since b u t little more solvent is necessary than required to wet the drug, it is very economical of solvent. 6-The extraction can be stopped at any moment by closing the stopcock. ”-Since the drug is constantly bathed with solvent, no fissures form through which the solvent flows and therefore there is no danger of incomplete exhaustion.
Advantages of Apparatus
Acknowledgment is made to C. C. Glover, of the University of Michigan, for advice and encouragement during the progress of the work.
1-It is much cheaper than a Soxhlet of equal size. 2-Any part, if broken, can easily be replaced at small cost.
Acknowledgment
Automatic Devices for the Extraction of Powdered Materials’ By S. Palkin and H. R. Watkins DRUG CONTROL LABORATORY, BUREAUOB CHEMSTRY.WASHINGTON, D . C.
tinuous agitation of the susTwo automatic devices for the extraction of solid subpended mass by means of tionl4,*several automatic stances, particularly plant drugs, are described. One pressure from solvent vapors devices for the extraction is an inexpensive, simple device, in which the extracting characterize the second or of liquids by immiscible solsolvent is made to flow rapidly upwurd through the more complex form, V. vents were described. By a sample and is continuously filtered through a cotton The value of sending the simple modification the apfilter device back into the heating vessel. Absence of hot solvent upward through plication of one of these liquid a thimble and upward flow of solvent keeps the powthe mass, thereby keeping the extractors may be extended dered material loosely suspended. The circulation ma t e r i a 1 loosely suspended to the extraction of powdered principle causes the solvent to flow through the whole and permitting very rapid or other solid material. Anmass of sample evenly with no stagnant central cores, c i r c u l a t i o n of the solvent o t h e r a n d somewhat more as might be the case where a thimble is employed. throughout the mass, has long complex form is based on the The same extractor vessel or jacket may also be used for been r e a l i z e d . Practical principle of forcing solvent the liquid extractors previously described. difficulties of effecting convapors into the suspended The other device, somewhat more complex, makes tinuous filtration during exmass to be extracted. use of the pressure effect of the solvent vapors to protraction exist, however. The literature c o n t a i n s duce continuous agitation of the suspended sample. many articles on the forms of One of the simplest forms Continuous filtration is effected in the same way that embodying the principle of extraction devices and comit is in the simple form. This apparatus is applicable mercial catalogs show numerthe continuous upward curto the extraction of liquids as well. ous types of such apparatus rent is described by Budde2 actually available. In the for t h e extraction of wax. main, those now used for the extraction of solid material fall Several slight variations of this form are also noted.6J1s21 into two general classes: (a) those in which the fresh solvent The difficulties with this very simple form are not appardrops from the condenser into a reservoir containing the ent from the description. They manifest themselves in material enclosed in a thimble for extraction and periodically practical application. Whenever a charge to be extracted siphons back into the heated vessel, most of which may be is confined between two layers of filtering material such regarded as employing some modification of the Soxhlet as cotton and the extraction solvent is a t the boiling point, principle; (b) those which involve the continuous percolation a pocket of vapor forms between the sample and upper of hot solvent downward through the mass to be extracted, layer of filtering material. This prevents the passage of and may be regarded as similar in principle to the Knorr, solvent all the way down through the supply tube and Bailey, and Riley extraction apparatus. causes the freshly condensed solvent to spill over the top The extensive use of these solid extractors is evidence of of tube, thus diverting the solvent from penetration of the their value in analytical work. I n practically all cases a mass to be extracted. This is particularly true when ether thimble, usually paper or cloth, is necessary for carrying the is the extracting solvent. Free communication with the charge. The solvent is made to pass downward through the atmosphere or vapor directly above the solvent is essential mass. to uninterrupted circulation of solvent upward through the Passing a continuous current of solvent upward through the sample to be extracted. Filtration in our apparatus is acpowdered material to be extracted and eliminating the thimble complished by means of a simple vertical filtering partition. characterizes the simple form of extractor 8. This and con-
I
N A previous p u b l i c a -
1 Presented under the title “Automatic Devices for the Extraction of Plant Drugs” before the Division of Chemistry of Medicinal Products at the 72nd Meeting of the American Chemical Society, Philadelphia, Pa., September 5 to 11, 1926. Numbers in text refer to the bibliography at end of article.
*
Type S Apparatus
Figure 1 shows the simple type, S. The jacket tube, A , is the same as that used for the extraction of liquids.’& Three other very simple and inexpensive pieces (aside from Erlen-
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INDUSTRIAL AND ENGINEERING CHEMISTRY
D
I-4OCrn-7
Wire neffinq wifh flap cut 6s shown
Device in posttion Nap d . s JUS/ be/ow the overf/oH insert absorbent coifon under f/dp
Condenser
Absorbenf
cotfon he/d with wire
Vol. 19, No. 4
the apparatus has been found convenient: The jacket, A , is joined to the Erlenmeyer flask, using a cork stopper wrapped with tin foil. The long supply tube, B, is wrapped with cotton a t its lower end, drumstick fashion, using thread or resistance wire, such as nichrome, to tie it around, and is then inserted in jacket tube A . The atering device, F, is inserted, so that the lower end of the flap dips a little below the overflow. The weighed powdered sample, usually 10 grams, is then introduced into the annular space between B and A by means of a funnel with a wide stem. The small funnel tube, C, is inserted into tube B and enough solvent or treating solution to wet the mass thoroughly is poured through C B, allowing it to soak as necessary. When ready for extraction, more solvent is added until the layer of solvent in the flask is about 2 cm. deep. The extractor is then hooked up to the condenser, using cork and tin foil for the extraction process. An electric hot plate with molten solder (soft solder) as contact material is an excellent heating medium. Owing to the €ire hazard, this should not be used when ether is the solvent. If the apparatus is so adjusted that the Erlenmeyer flask does not rest square on the ring but is slightly elevated to permit live steam to surround the flask, a steam bath serves this purpose admirably. In order to function efficiently, the extraction solvent should be made to boil as briskly as possible, so that a rapid, continuous stream of solvent will be seen flowing from the return tube. Where the material to be extracted requires special treatment before extraction, as alkaloid-bearing drugs with ammonia for liberation of the base, details of the procedure will vary somewhat with the drugs. The current of solvent should flow evenly upward, permeating the whole mass, and not so rapidly as to cause channeling. If a channel is formed the sample may not be uniformly wet with solvent, owing perhaps to the uneven distribution of moisture. In such a case, the jacket is disconnected from the condenser and the sample well stirred with long stiff wire. Type V Apparatus
Figure 1
meyer flask, condenser, etc.) complete the apparatus to be used for extracting solids. B and C ape straight tubes with flanged ends. B holds the absorbent cotton and C serves as a funnel for the recondensed solvent. The filtering device, D, E , F, and G, is made from wire screen with absorbent cotton as the filtering medium, though other filtering material may be preferable in special cases. Fifteen-mesh galvanized screen has been found to serve very well. It is cut approximately to the dimensions indicated and bent into shape by hand or with the aid of pliers. Grooving of the flap and of the portion above the flap is necessary in order to give free communication with atmosphere, thus preventing the formation of a column of liquid above the overflow point. As the filtering screen when bent into shape forms an incomplete cylinder, the device is automatically adjustable, so that after the cotton is inserted it can be made to slide easily into the jacket tube, A , as indicated in G, and yet tight enough to be held firmly in place. The cotton is cut into a flat rectangular layer not quite so wide (within 1 or 2 cm.) as the circumference of the cylindrical wire screen, and long enough to go a little beyond (about 0.5 cm.) the lower end of the screen. In this way the cotton will not slide up when the device is inserted. The following order of charging with sample and setting up
Figure 2 shows the more complex type, V . The complex‘ type differs from the simple type in that provision is made for agitating the suspended mass during extraction by means of the solvent vapors. The principal unit (without water jacket, Erlenmeyer flask, etc.) is made of Pyrex glass, all joints being glass-sealed (H, Figure 2). The “cut out” or window for the overflow is ground out by an emery wheel rather than blown, so as to provide a smooth and true cylindrical surface over which the cork may slide. The tube K serves merely as an inverted test tube to force vapors downward, the upper portion forming a handle. The filtering device is made in exactly the same way as that used for the simple form (D, E , and F , Figure 1) except for the dimensions, which conform to the size of the tube e. v. The relative position of the filtering device with respect to the top or overflow, T . t., is the same as that for the simple form, G, Figure 1. The water jacket fits firmly on the unit H by means of one rubber stopper a t the lower end (water tight) and another (in which a segment has been cut out) a t the upper end. The jacket is provided with an outlet tube, 0. t., and receives the water through a small-diameter rubber tube that slides through the segment cut out down to any desired level. This rubber tube may then be used as a siphon to drain the water from the jacket. The manner of heating the Erlenmeyer flask and contents is the same and the charging of the apparatus with sample, etc., and the order of procedure are much the same as for the simple form. The actual operation ( V ,Figure 2) is as follows: The solvent vapors from the Erlenmeyer flask pass through
INDUSTRIAL A N D ENGINEERING CHEMISTRY
April, 1927
the window, w,and then upward through the tube v . t. They are forced downward through the inverted test tube, K , which merely rests on the bottom of the extracting vessel, e . v. The vapor passes upward through the suspended mass of sample, condensing in its upward course. The condensed extracting solvent passes through the filtering device, f. d. (like S, Figure 1) in the course of its overflow into the return tube, r. t., down to the bottom of the tube v. t., and rises to the window, w,where it ultimately overflows into the Erlenmeyer flask. When functioning properly there should be considerable agitation in the extractor e. v., and the column of liquid in the return tube, T . t., generally stands a t a uniform level, approximately 5 to 8 cm. from the overflow point,’depending on the character of solvent. Practical Application
Exact details for the treatment of a sample preparatory to extraction, minimum period of extraction, etc., w ill vary with the character of the material to be extracted. Table I shows the results obtained in the Drug Control Laboratory on a number of Dlant drugs. The extraction Deriod generally employed was*from 1 to 2 hours. Particular attention is called V
n Segmenf cut from
537
preferably for a day, and then extracted with ether, using the automatic device for solids. The ether solution of alkaloid is then subjected to a purification process similar to that described for liquid preparations,26with subsequent extraction of the alkaloid from solution, either by hand or with the aid of automatic liquid extractors. The titration, etc., is carried out as described for hyoscyamine and atropine in another paper. Table I
DRUG
Hyoscyamus“ Ipecac
u.s. P. I X
u.s. P. x
Per cent 0.068 1.99
Per cent 0.084 1.96
Belladonna leaveso
0.47
0.50
Belladonna leavesa (sample 2 ) Belladonna rooto
0.42 0.53
0.42 0.51
Stramonium
0.33
0.35
Nux vomica
2.63
g;;:&c;; Per cent 0.198 2.10 2.12 0.55 0.55 0.58 0.63 0.60 0.44 0.40 2.62b 2.54~ 2.55~
a The alkaloid was found t o have full hyoscyamine mydriatic power by “cat eye” tests. b Benzene. c Chloroform.
Acknowledgment
The authors wish to express thanks to Mr. Baker, of the Office of Development, for the drawings, and to Mr. Symonds, of the Bureau of Chemistry, for the glass-blowing. Bibliography 1-Aron, Biochem. Z . , 13, 134 (1913). 2--Budde, J. SOC.Chem. Ind., S3, 184 (1914). 3-Chattopodhyay, I b i d . , 82, 1145 (1913). 4-Cordonnier, Bull. sci. pharmacol., 27, 42 (1920). 5--Freund, Chem.-Ztg., 88, 802 (1914). 6--Friese, Pharm. Zentralhulle. 64, 641 (1913). 7-Gebhard and Thompson, Chem. News, 99, 124 (1909). 8--Hagen, Chem.-Ztg., 45, 19 (1921). %Knopfler, 2. anal. Chem., 28, 671 (1889). l&Rulka, Biochem. 2..lS, 134 (1908). 11-Landsiedl, Chem.-Zlg., 26, 275 (1902). 12-MacNider, J. Ind. Eng. Chem., 6, 150 (1913). 13-Marin0, A n n . Lab. Gabelle, 6 , 651 (1912). 14--Palkin, Murray, and Watkins, Ind. Eng. Chem., 17, 612 (1925) Ij-Palkin and Watkins, J. A m . Pharm. Assoc., 16, 21 (1927). 16--Patterson, J. SOC.Chem. I n d . , 43, 281T (1924). 17-Quincke, 2. Nohr. Gcnussm., 22, 171 (1911). 18-Sand0, Ind. Eng. Chem., 16, 1125 (1924). Pharm. Weekblad, 60, 375 (1923). lg-schaap, Chcm.-Ztg., 46, 43 (1922). 2@-Schaefer, 21-Schmalfuss and Werner, J. prakl. Chem., 108, 365 (1924). 22-Simion, Chem.-Zlg., 46, 592 (1921). 23--Tcherniac, J. Chcm. SOC.(London), IlbT, 1090 (1919). 24--Vigreux, Bull. SOL. chim., [4] 6, 699 (1909). 25--Walpole, Chem. A’ews, 102, 129 (1910). 26-Watkins and Palkin, J. A m . Pharm. Assoc., 14, 1099 (1925).
New Process Reduces Chilean Nitrate Cost Figure 2
to the results on hyoscyamus and belladonna. The extraordinarily high alkaloid yield obtained by this automatic extraction as compared with pharmacopeia1 methods is significant, aside from its labor-saving element. Incidentally, the alkaloid from hyoscyamus and belladonna thus obtained has full hyoscyamine mydriatic power. The preparation of this drug for extraction will be outlined in principle only and may serve as a typical procedure. For hyoscyamus the powdered drug is soaked in mixture of strong ammonia, alcohol, and ether for several hours, or
A reduction of more than 50 per cent in the production cost of nitrates as a result of new processes for its extraction from nitrate-bearing rock has recently been announced by the government of Chile. Under the old boiling process for nitrate production only a small percentage of ore containing less than 40 per cent of nitrate could be worked. Under the new processes ore which contains as low as 15 or 18 per cent of nitrate can be worked. This reduction in production costs is expected t o influence the market for the product in this country. In addition it will enable the Chilean nitrate producers t o compete more profitably with producers of synthetic nitrogen, which has been in large demand because of the prices of the Chilean product. If the market for Chilean nitrates becomes more favorable as a result of reduced prices, the prospect of a n economic crisis which Chile has been facing as a result of the increasing use of synthetic nitrates will be substantially obviated.
