Enclosed Laboratory Apparatus for Effecting Repeated Crystallizations from Solvents ~~
JOHN D. PIPER, N. A. KERSTEIN, AND A. G. FLEIGER The Detroit Edison Company, Detroit, 3lich.
I
S 1937 the authors ( 5 ) described a type of enclosed glass
impurities from some compounds, notably lauryl sulfonic acid (4). The apparatus described in the present paper was designed to permit the use of a solvent as well as to enable repeated crystallizations to be effected conveniently in a closed system. Figure 1 shows the apparatus in the filling position just after it has been separated from a vacuum still for which the apparatus served as the receiver. The fritted Pyrex disk was made of coarse Pyrex powder, that was ground, sintered, and sealed in the tubing according to the techniques described by Kirk, Craig, and Rosenfels (3) and by Cool and Graham (2). Inasmuch as fritted disks in Pyrex tubes are now commercially available (I), the somewhat time-consuming task of constructing and sealing-in the disk is no longer necessary. Figure 2 shows the apparatus with the solvent bulb attached and with the space between the glass partitions evacuated preparatory to breaking the partitions with the hammer enclosed within the bulb. The solvent must be more volatile than the impurities to be removed from the compound. The pressure within the bulb is usually the vapor pressure of the solvent, which is distilled into the bulb under vacuum. After the partitions are broken the solvent is transferred to the compartment containing the compound and the bulb is detached by sealing off the large bore capillary and pulling the softened glass apart. Solution of the compound is next effected; if necessary, the entire apparatus is warmed. The solution is then passed through the fritted disk and is allowed to crystallize with the apparatus in the position shown in Figure 3. This prevents insoluble impurities from entering the compartment from which the purified compound is finally removed. If necessary, a cooling bath is used as is shown.
apparatus in which repeated crystallizations of compounds from their own mother liquors were effected while these compounds were completely protected from atmospheric contamination. Many hygroscopic and oxygen*usceptible compounds mere successfully purified in various modifications of this type of apparatus for use in research on dielectrics. Crystallization from the mother liquor was found, however, to be an ineffective method for removing colored
OLlDlFlED ISTILLATE
FIGVRE 1.
.4PPARATUS I S F I L L I S G POSITIOX
HAMMER FOR BREAKING PARTITIONS
FIGURE 2. APPARATUSWITH SOLVEST BULB ATTACHED
FIGURE3. CRYBTALLIZATION POSITION
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FIGURE 4. DRAINING POSITION
ANALYTICAL EDITION
September 15, 1942
0
n
RYSTALS
PARTITION FOR REMOVAL OF CRYSTA AFTER FINAL CRYSTALLIZATION
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disk as is showi in Figure 4. Next the apparatus is rotated 180" in the direction shown by the arrow. Figure 5 shows the apparatus in the position in which a part of the solvent is returned to the crystals by distillation. To effect the distillation either a heating bath is applied to the compartment containing the solution, as is shown, or a cooling bath is applied to the compart'ment containing the crystals. Re-solution and recrystallizat'ion are then effected in that order, and the apparatus is again inverted, t,his time in the direction of the arrow shown in Figure 5 . The cycle is repeated as many times as is thought desirable. In the purification of lauryl sulfonic acid, which prior to crystallizat'ion n-as subjected to molecular distillation in a small allglass still, three crystallizations from purified hexane were sufficient t'o remove all noticeable traces of colored impurity that persisted in the distillate. Obviously, by applying the technique previously described (4), the apparatus is also suitable for crystallizing compounds from t'heir own mother liquors.
Literature Cited
U FIGIJRE 5 . DISTILLATION POSITION
The first crop of crystals is obtained by inverting the apparatus and allowing the solution to drain through the fritted
(1) Anon., "Recent Developments in Laboratory Apylianceu", p. 25, Fisher Scientific Co., Pittshurgh, and Eimer 8- Amend, New York (1941). ( 2 ) Cool, R . D., and Graham, J. D., ISD. E N G .CHmr., . ~ N A L .ED.,6, 479 11934).
(3) Kirk, P. L., Craig, R . . and Hosenfels, R . S., Ibid., 6, 154 (1934). (4) Piper, J. D., Fleigei, A . G.. Smith, C. C., and Kerstein, N. A., (submitted t o IKD. ENG.CHEY.). ( 5 ) Piper. J . D., and Kerstein, N. A , , Ibid.. 9, 403 (1937).
An All-Glass Buret Svstem J
THEODORE F. LAVINE The Lankenau Hospital Research Institute, Philadelphia. Penna.
T
HE accompanying sketch illustrates an all-glass buret supply system which is convenient for solutions that find only occasional use. The necessary flexibility of the system is furnished by the use of ball and socket joints. The assembly may be easily dismantled and cleaned and used for different solutions and thus possesses an advantage over existing types of all-glass buret assemblies which are so complex that each buret is usually left permanently with the reagent bottle. The device has been used successfully with glacial acetic acid solutions, as well as with aqueous solutions of iodine. etc The systeni is easily constructed from standard itenis by one able to make simple seals. (These items, constructed from Pyres may be obtained from the Ace Glass Co., Vineland, N. J.: which
also will fabricate the complete setup.) There are required one f 24/40 gas inlet adapter and t x o complete 12/5 spherical (ball and socket) joints. The reagents are stored in 1-liter glassstoppered (T 24/40) bottles. The buret may be filled by suction or by a hand-pressure bulb, or by suitably altering the design. gravity flow niay be employed. It is convenient to have a series of burets of various sizes which map he used interchangeably as IlWtll?d.
