Quantitative Analysis for Ethylenediamine in the Presence of Hydroxyalkylamines DALE HUGGINS and W. C. DRINKARD' Department of Chemistry, Universify of California, 10s Angeles, Calif.
b A quantitative gravimetric procedure is presented for the determination of ethylenediamine in the presence of large amounts of hydroxyalkylamines. Ethylenediamine is precipitated as a Schiff's base with salicylaldehyde from an aqueous solution of pH 9.
N
o
QUAKTITATIJ-E analytical method for ethylenediamine in the presence of hydroxyalkylamines has been reported previously. The method reported here is shown to give a good recovery of ethylenediamine in the presence of both ethanolamine and N hydroxyethylethylenediamine.
EX PERlMENTA 1
Reagents. Salicylaldehyde solution. Dissolve 5.0 grams of sodium hydropide in 200 ml. of water. Add 10 ml. of salicylaldehyde and stir rapidly until the oily droplets have dissolved. If a light yellow precipit a t e forms, filter the solution through a n alkali resistant filter paper b u t d o not wash. T h e solution is not stable and must be prepared fresh each day. Sulfuric acid solution. One part concentrated sulfuric acid plus five parts water (by volume). The solution is 27% sulfuric acid b y weight. Sodium hydroxide solution. One part sodium hydroxide plus nine parts water (by weight). The solution is 10% NaOH by weight. Hydrochloric acid solution. One part concentrated hydrochloric acid plus five parts water (by volume). The solution is 7 7 , HC1 by weight. Sodium sulfide mash solution. Add 1 nil. of the sodium hydroxide solution described in paragraph 3 above, to 200 nil. of 11-ater. Bubble hydrogen sulfide gas into the solution a t a moderate rate for 5 minutes. The solution should be prepared fresh each day. Procedure. A . FORS A h w L E s CONTSIKIXG OXLYETHYLEKEDIAMISE, SH Y D R O X Y E T H Y L E T H YLE N E D I A hf I K E . ~ N D CTHANOLAMIXE.Place the
sample containing 25 t o 50 nig. of ethylenediamine in a 400-ml. beaker and dilute t o a volume of 275 ml. with distilled water. Present address, Fabrics and Finishes, , E. I. du Pont de Nemours & Co., Wifmiington, Del. 1
De t
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ANALYTICAL CHEMISTRY
Add 50 ml. of the salicylaldehyde solution t o the sample. Slowly add 27y0 sulfuric acid to the solution, dropwise while stirring, until a precipitate just begins to form. Continue adding the sulfuric acid slowly, stirring the solution thoroughly after addition of each drop, until upon allowing the solution to come to rest, the precipitate coagulates and settles rapidly. At this point the red color of the phenolphthalein should have disappeared completely, and the p H of the solution should be approximately 8. If the amount of ethylenediamine in the solution is very low ( 5 or 6 mg. or less), the precipitate will be slow in forming. I n this case, add 27y0 sulfuric acid to the solution until an approximate p H of 8 is reached. It may be necessary to scratch the side of the beaker with a glass rod to initiate precipitation. Allow the solution and precipitate t o stand for 1 hour, stirring occasionally. Filter the precipitate on a tared, sintered glass crucible of medium porosity. Wash the precipitate four times with water (about 20 ml. of water total volume). D r y the precipitate in an oven at 70" C. for 5 hours. Weigh the cool crucible and contents to obtain the weight of the precipitate.
Weight of ethylenediamine = 0.224 x (weight of precipitate). B. PROCEDURE FOR SAMPLES CONTAINIKG COBALT IONAKD ACTIVATED
CARBONIN ADDITIONTO ALKYLAMINES. Filter the
HYDROXY-
sample to remove carbon. Place an aliquot of the solution containing cobalt and 25 t o 50 mg. of ethylenediamine in a 250-ml. Erlenmeyer flask and dilute with water t o an approximate volume of 50 ml. Adjust the p H of the solution with the 10% sodium hydroxide and 7% hydrochloric acid solutions to about 9, as indicated by pHydrion paper or a similar material. Bubble technical grade hydrogen sulfide gas into the solution at a moderate rate for approximately 10 minutes. Stopper the flask and allow the contents to stand for 30 minutes. Filter the contents of the flask through a Gooch crucible containing a retentive asbestos filter pad and wash the flask and crucible four times with the sodium sulfide solution. Transfer the filtrate t o a 400-ml. beaker. Acidify with the 7% hydrochloric acid solution and add 10 ml. in excess. Boil the solution on a hot plate, while stirring, until approximately 50 ml. of the solution has evaporated. Cool the solution to room
Table I. Recovery of Ethylenediamine from Synthetic Samples Containing Hydroxyalkylamines
En 0.00317 0,00317 0.0031'7 0.00317 0.00317 0.00317 0.02.537 0.02537 0.02537 0.02537 0,02537 0.02537 0.05074 0.05074 0.05074 0.05074 0,05074 0.05074 0,10148 0.10148 0.10148 0.10148 0,10148 0.10148
Added, g. Etolen Ethanolamine 3.00 3.00 3.00 1.50 1.50 1.50 3.00 3.00 3.00 1.50 1.50 1.50 3.00 3.00 3.00 1.50 1.50 1.50 3.00 3.00 3.00 1.50 1.50 1.50
0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10
Recovered en, g.
Recovery, %
0.00283 0,00313 0.00304 0.00311 0.00316 0.00302 0 02478 0 02503 0 02507 0 02413 0 02420 0 02399 0 05005 0 05078 0 05024 0 04926 0 04974 0 04929 0 09935 0 09883 0 lO0Tl 0 09993 0 10053 0 09983
90.9 98.8 96.0 98.1 99.7 95.3 97.8 98.6 98.8 95.1 95.4 94.6 98.5 100.1 99.0 97.1 98.0 97.1 98.0 97.4 99.2 98.5 99.1 98.5
Table 11. Recovery of Ethylenediamine from Synthetic Samples Containing Hydroxyalkylamines, Carbon, and Co(ll)
Sdded, g. Eli
Etolen
Co(I1)
0.00317 0.00317 II.. . 02.i37 --- - . 0.02537 0,05074 0.05074
3.00 3.00
0.05 0 05
Ethanolamine
Recovered en, g.
Recovery,
0.00251 0.00287 0.02416 0.02455 0.04943 0.04959
79.1 90.4 95.3 96.8 97.4 97.8
-1 . 31
n- . nR .-
0.10 0.10 0 10
1.3-1 1.34 1.34
0.05 0.05 0.05
0.10 0.10
__
temperature. Filter the cool solution again through a Gooch crucible containing a retentive asbestos filter pad t o remove any sulfur or sulfides which may have formed. Return the filtrate t o a 400-nil. beaker; add 5 drops of phenolplithalein indicator; add 10% sodium hydroxide solution until the solution turns red. Add 50 ml. of the salicylaldehyde reanent t o the solution in the beaker and di1;te to 325 nil. The ethylenediamine is then precipitated arcording to procedure A . RESULTS
T o evaluate the procedure, analyses were performed on synthetic samples containing knonm amounts of ethylenediamine, ethanolamine, and .l’-hydrosy-
0 . io
%
ethylethylenediamine. Table I lists the weights of t h e various components in the synthetic samples, the weights of ethylenediamine recovered, and the per cent recovery. Samples were run in triplicate. Because the procedure was used for the determination of ethylenediamine in the presence of cobalt ion and activated carbon as well as the hydroxyalkylamines, a second series of synthetic samples was run with this more complex system. Activated carbon (2.5 grams) was present in each sample. Results are shown in Table 11. DISCUSS10 N
During a n investigation of various cobalt-amine complexes it became necessary to determine quantitatively ethyl-
enediamine (en) in the presence of much larger concentrations of -V-hydroxyethylethylenediamine (etolen), ethanolamine, carbon, and cobalt ions. A gravimetric procedure was developed by which ethylenediamine is precipitated with salicylaldehyde from a solution containing the hydrosyalkylamines according to tlie following reaction:
The method was then extended to include the analysis for ethylenediamine when carbon and cobalt ions are also present. The precipitation of ethylenediamine is performed from a slightly basic, aqueous solution. Under these conditions, N - hydrosyethylethylenediamine and ethanolamine do not precipitate. RECEIVED for review ISoveniber 2 , 1961. Resubmitted August 30, 1963. Accepted October 12. 1962.
Polarographic Determination of Uranium(lV) in Sodium Tripolyphosphate Supporting Electrolyte H. E. ZITTEL and LOUISE 8. DUNLAP Analytical Chemistry Division, Oak Ridge National laboratory, Oak Ridge, Tenn.
,The anodic behavior of U(1V) at the D.M.E. in a sodium tripolyphosphate -sodium sulfate medium was studied. In this medium, U(1V) exhibits an anodic wave whose € 1 ~is -0.19 volt vs. S.C.E. and whose i d is proportional to the U(IV) concentration. The proper conditions for analytical use of the anodic wave have been established, and the effects of pH and uranium concentration have been studied. The best results were obtained in a 6 w./v. % NasP3010-0.1M NazS04 medium of pH 9. The error of the U(IV) determination is about +3?&. The U(VI) content of a sample may also be determined by measurement of the U(V1) cathodic wave at - 1.1 volts vs. S.C.E. in this medium. The possible interferences by various cations and anions have been studied. Of those ions studied, only Fe(ll) interferes to any extent.
I
THE ANALYSIS of solutions of uranium, it is sometimes advantageous to be able to determine both the U(1V) and the U(V1). In other methods for the determination of U(IV), the U(1V) is chemically oxidized to U(V1) (6, 8 ) . The U(1V) can also be determined indirectly in an acid medium by analyzing the sample for U(V1) before and after oxidizing the U(1V) by chemical treatment and calculating the U(1V) bv difference (7‘). Harris and Kolthoff (3)studied the polarography of uranium in various media, mostly acids. Alkaline electrolytes have not been used extensively in the electrometric studies on uranium. P;ibil and Blazek (9) used an alkaline carbonate medium for the estimation of uranium. Ascorbate and phthalate (10) have also been used for the polarographic determination of U(V1) in alkaline media. The analytical use of the anodic
N
reaction of U(1V) at the D.Tv1.E. has not been described previously. No literature references have been found on the use of sodium tripolyphosphate supporting electrolytes for the anodic oxidation of U(1V). The polarographic method described in this paper is based on the fact that U(1V) in a solution of sodium tripolyphosphate exhibits a n anodic wave whose height is directly proportional to the concentration of U(1V) present in the solution polarographed. The same medium can also be used for the polarographic determination of the U(V1) present ( l a ) . The method is accurate t o * 3 7 , in the concentration range from 100 t o 400 fig. per ml. Few of the common cations and anions a p t t o be present, except Fe(II), interfere when present in concentrations approximating that of the U(IV) present. VOL. 34, NO, 13, DECEMBER 1962
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