N O V E M B E R 1942
937
methylaminobenzaldehyde, was dissolved (50 mg. per cc.) in the sulfuric acid used in the test, thus eliminating the usual alcohol solvent as a variable. The solution against which the spectrophotometer was standardized was prepared simultaneously with the other solutions, received exactly the same treatment, and contained the same percentage of alcohol. Purification of Commercial Absolute Alcohol. The absolute alcohol (Rossville 200-proof Gold Shield) was allowed to filter by gravity through a 15-em. (6-inch) column of fuller’s earth. Residual aldehydes were removed ( 3 ) and the alcohol was redistilled from a weak hydrochloric acid solution. The spectrophotometer showed (Figure 1) that about 25y0 of the substances responding to the Komarowsky test had been removed in the filtration (curves A and B ) . This treatment reduced the higher alcohol content to approximately 1 part in 100,000 of ethanol. Immobilization of the higher alcohols as colored complexes, removal of these by absorption on fuller’s earth, neutralization of the colorless sulfuric acid filtrate, and recovery of the ethanol by high-vacuum distillation gave a product which gave a strong Komarowsky reaction even in the cold (curve E , Figure l), much more pronounced than untreated alcohol. Synthetic Ethyl Alcohol. Methods which did not involve the use of reagents that might contain higher alcohols were considered for the synthesis of the ethyl alcohol. The saponification of p-aminobenzoate ethyl ester w&s found entirely suitable. The ethyl p-aminobenzoate (benzocain) was saponified in an all-glass apparatus. Five hundred grams were recrystallized
three times from dilute hydrochloric acid and washed repeatedly on the funnel with boiled distilled water. The moist solid was gradually added to the refluxing sodium hydroxide solution (130 grams in 500 cc. of boiled distilled water) contained in a 2-liter round-bottomed flask as rapidly as the ester went into solution. The refluxing was continued 0.5 hour after the ester had completely disappeared. The flask was chilled, the contents acidified slightly with hydrochloric acid, and the alcohol slowly distilled (preferably in the presence of nitrogen) through a very clean fractionating column and condenser. The distillation was discontinued a t 90” C. Yield: 85% of the theoretical. The alcohol was stored in amber glass-stoppered bottles in darkness and in contact with a piece of copper wire. Figure 2 shows the comparison of two synthetic alcohols of different proofs with a good grade of commercial alcohol of the same proof. The comparisons demonstrate that the synthetic alcohol has much less of the components present which give the Komarowsky reaction than does commercial alcohol of high purity. LITERATURE CITED
(1) Coles, H. W., and Tournay, U’. E., IND.EXG.CHEM.,ANAL. ED., 14, 20 (1942). (2) Stout, A. W., and Schuette, H. A , , IND.ENG.CHEM.,ANAL.ED., 5, 100 (1933).
R BCEIVED March
4. 1947.
Sand Filters in Analytical Chemistry SVERRE STENE Statens Institutt for Folkehelse, Oslo, Norway
HE principles of sand filtration, used in water purification, Tmay be applied in analytical chemistry with advantage in a number of cases, partly by using “sand” layers as an efficient support for other filtering media, and partly by using sand as the filtration medium proper. The products of the abrasives industry are available in finely graded powders of a great variety of grain sizes, made according to strict specifications, so that filters of highly reproducible characteristics can be made. Figure 1, A , shows a sand filter proper during a hot filtration, such as is regularly used a t this institute in the determination of starch in sausages by Grossfeld (3), modification by of Mayrhofer’s (6) method, where the proteins are dissolved by hot treatment with 8 yo alcoholic potassium hydroxide, filtered, and washed with 90% alcohol, and the starch is dissolved in cold hydrochloric acid and estimated by polarization. Grossfeld used filters of asbestos on glass wool. But it proved difficult t o obtain filters of sufficient retentivity coupled with a low reproducible filter resistance for use in routine work. The filter tube is suspended by a copper wire in the form of a hook a t the lower end, with a loop around the neck of the flask, which is placed on a hot water bath during filtration, the filter being kept hot by the vapors. I n the bottom of the filter a n unspherical glass bead is placed. Above it are two layers of specially treated alloxite (aluminum oxide), first a 1- to 2-cm. layer of grain size KO.36 and then a 3- to 4-em. layer of S o . 80. Such filters have proved very satisfactory for a number of years and may be used repeatedly. If the bead fits too closely, the filter may be filled with water, and the bead pushed upward a little with a glass rod. Some grains slip down between the bead and the wall, forming an annular space for the outlet of the filtrate. In place of the glass bead a little glass wool may be used. If a filter is to be used only once, it is advantageous to prevent the trapping of air bubbles by closing the outlet, filling the filter LTith water, and pouring the grains through the water. In permanent filters the top layer may be stirred with a glass rod, after the filter is filled with liquid. If the surface of the filter gets clogged during filtration, stirring the surface with a rod will often be of advantage. If very fine grains are to be used for the filter, an additional supporting layer of medium-sized grains may have to be introduced. Then it is an advantage to have the top layer
as shallow as possible. In order to prevent this layer from being stirred up during filtration, it may be covered by a layer of coarse grains. In some tentative experiments on the determination of cellulose in polluted rivers the replacement of a surface filtration by a filtration in depth seemed promising, using Bmall filters of 8- to 10mm. inside diameter and an 8-cm. filter height of coarse-medium coarse grains. Ordinary surface filters were rapidly clogged, but in these special filters the cellulose fibers were retained by the uppermost coarse layer, while the fine silt was allowed to pass through the filter, so that a large quantity of water could be filtered rapidly, if necessary in the field. The cellulose might be
u Figure 1
938
V O L . U M E 19, NO. 11
purified by the method of Kurschner and Hanak ( 5 ) and estimated by chromic acid oxidation according t o von Fellenberg (8).
B shows a filter of the Gooch type, of 12-mm. inside diameter and ca. 30-mm. over-all length. It has a bottom layer of No. 36 alone or covered by No. 80 and asbestos. For convenience during filtration a n extension tube of the same bore may be connected by rubber tubing. After removal of the asbestos layer, the filter and filter cake may be treated with solvents in a 50-ml. Erlenmeyer flask with a condenser. The liquid may be removed through the filter stick depicted in C, where the layer close to the constriction is No. 36, followed by KO.80, and then by asbestos. The bent construction is used for liquids attacking rubber, the filter stick being connected to the suction flask by a bent adapter. The filter resistance is considerably less than in the filter sticks described by Dunbar ( I ) and Kolthoff and Amdur ( 4 ) , where the asbestos is supported by only single glass bead. When the residue is to be titrated it may be blown out when the filter is wet or loosened by a glass pick. For the "sand" filter proper only alloxite has been used, in sizes 36, 60, 80, 100, and 120. On treatment with strong hydrochloric acid alloxite gives off some iron, and some of the aluminum
oxide is peptized. Before use large portions of alloxite were treated for several weeks a t room temperature and on the steam bath with new portions of hydrochloric acid. Then folIowed treatment with chromic-sulfuric acid, washing, and ignition a t a high temperature in a muffle furnace. The lack of complete insolubility causes uncertainty for a number of purposes. During the occupation of Norway it was impossible t o obtain samples of the powders of Jena gerateglas 20 and pure quartz for Jena filter crucibles. Where the powders serve only as supports for an asbestos mat, they need not be finely graded and may be made of crushed quartz after a simple sieving. LITERATURE ClTED
(1) Dunbar, R. E., IND. ENG,C H E b i . , ANAL.ED.,9, 355 (1937). Fellenberg, Th. von, Mitt. Lebensm. Hug., 21,385 (1930). Grossfeld, J., 2.Untersuch. A'ahr. Genussm., 42,29 (1921). Kolthoff, I. M.,and Amdur, E., IND.EKQ.CHEW,ANAL.ED., 12,177(1940). ( 5 ) Kurschner, K., and Hanak, A., 2. Untersuch. Lebensm., 59, 484 (1930). (6) Mayrhofer, J., 2. Untersuch. Nahr. Genussm., 4, 1101 (1901). RECEIVED January 17, 1947.
Apparatus for Distilling Aniline E. L. RUH AND J. L. ROSSETTIE Standard Oil Development Co., Standard Znspection Laboratory, Bayonne, N. J . A P P R O V E D procedure ( I ) for determining the aniline point of petroleum products requires that the aniline be distilled on the day of use, the f i s t and last 10% being discarded. Aniline is a highly toxic material, particularly when its vapor is inhaled, and the apparatus described in this report was devised to ensure minimum danger as well as maximum convenience in distilling this reagent. The apparatus illustrated is used as a complete assembly and is taken apart only for periodic cleanings. All connections are made by means of ground-glass fittings, and the connecting parts are held tightly together by means of small steel springs attached to hooks fused on the glass. The flask is a stock 250-ml. flask modified with an enlarged outlet, a removable filling arm, and a stopper. The condenser has the usual outer jacket inner tube, and adapter all made in a single piece. In the top of the adapter section is a small side arm, which is attached to one of two available water aspirators by means of a
A 12I)(QIco"sER
ENLARQED VIEW OF SECTION &A
piece of rubber tubing containing a glass T-piece. The receiver is a graduated cylinder of 100-ml. capacity, made of actinic red glass, with a stopcock a t the bottom. In the operation, a small mark is made on the bulb of the distillation flask, to indicate the level of 100 ml. The filling arm is fitted into the distilling flask with the lower end dipping into a bottle of aniline. The water aspirator is turned on and a finger is placed over the open end of the T-piece and left there until 100 ml. of aniline have been drawn into the flask. The bottle of aniline should be removed and an empty beaker held below the filling arm. The finger may then be removed from the T-piece. The filling tube is removed from the distilling flask and inserted in the filter flask. Water is poured into the beaker and the filling arm thoroughly washed. The flask is stoppered and heat is applied, preferably from an electric heater. When the first 10-ml. portion has collected in the receiver, it is drawn off into a small beaker and discarded, and the beaker is immediately washed with water. Heating is continued until some 78 ml. of aniline have collected in the receiver. A t all times, water is kept running through the aspirator connected to the adapter to remove any aniline vaDors from the vicinity of the opkrator. When the apparatus has cooled completely, TO FIRST the stopper of the distillation flask is removed, the filling arm, which is still connected to the suction flask, is inserted in the distillation flask, and the aniline remaining in the flask is drawn off by means of suction from the second aspirator. The filling arm is then withdrawn from the distilling flask, protected with a beaker, and rinsed with water as before. The actinic red glass of t'he graduated receiver protects the distilled aniline from the characteristic darkening caused by exposure t,o light. This makes it possible to withdraw test portions direct from the receiver, which serves the joint purpose of a measuring graduate and a storage receptacle. The use of the aspirator prevents any escape of aniline vapors into the atmosphere, and the general procedure for charging the flask and withdrawing test portions from the graduated receiver minimizes the possibility of contact of liquid aniline with the skin of the operator. LITERATURE CITED
ANILINE DISTILLATION APPARATUS
Figure 1
(1) Am. Soo. Testing Materials, Tentative Standard Method D611-46T. RECEIVED February 7, 1947.
