1758
ANALYTICAL CHEMISTRY
Sodium hydroxide, 0.2A' in 60% dioxane. Organic solvent, cyclohexane or s-tetrachloroethane.
The main advantages of the method offered here are that primary and secondary amines can be determined in the presence of tertiary amines, and the method is applicable to amines which are highly soluble in water. Certain amines fail to react with 1fluoro-2,4-dinitrobenzene because of steric hindrance. The sensitivity of the method permits the determination of quantities in the order of 0.1 micromole of amine.
PIPETS
For the beat results, the aliquot8 of amine solution should be measured with micropipets. Reasonably good results can be obtained with 1-ml. Mohr pipets on which the tips have been drawn to a fine point. PROCEDURE
Pipet carefully to the bottom of a 25-ml. glass-stoppered cylinder 0.1 ml. of aqueous amine solution containing 10 to 1007 of amine, 0.05 ml. of l-fluoro-2,4-dinitrobenzene in alcohol, and 0.1 ml. of bicarbonate solution. Mix thoroughly and place the cylinder in a 60' water bath for 20 minutes. Add 0.4 ml. of 0.2N sodium hydroxide in dioxane and continue heating for 60 minutes. Dilute t o 10 ml. with distilled water and extract with 10 ml. of cyclohexane. (In the case of ethanolamine and other highly water-soluble amines, extract with s-tetrachloroethane. ) Separate the liquid layers and read the absorbance of the orgsnic solvent a t the wave length of maximum absorption as shown in Table I. Blanks on the reaction give an absorbance of 0.005 or less in cyclohexane, 0.010 to 0.025 in s-tetrachloroethane, depending upon the wave length.
ACKNOWLEDGMENT
The authors wish to thank Boyer Clausen for the drawing of Figure 1. LITERATURE CITED
(1) Brodie, B. B., and Udenfrlend,
S.,J . Bzol. C'hem., 158, 705
(1945).
(2) Cook, H. G., and Saunders. B. C . , Bzochent. J., 41, 55s (1947). (3) Davies, D. F., Wolfe, K. AI., and Perry, H. AI., J . Lab. Clsn.
Med., 41,802 (1953). (4) hIcIntire, F. C., J . Am. P h a r m . Assoc., Sci. Ed.. 41, 277 (1952). (5) RIcIntire, F. C., White, F . B , and Sproull. 11.. Arch. Biochem 29, 376 (1950). (6) Sanger, F., Biochem. J., 39,507 (1915).
SUMMARY
l-Fluoro-2,4-dinitrobenzene has a potentially extensive usefulness for the determination of primary and secondary amines.
RECEIVED for review March 7, 1953. Accepted July 2.5 1953.
Determination of Zirconium in Aluminum Alloys Using p-Bromo- or p-Chloromandelic Acid ROLAND .4. PAPUCCI AND DIANE M. FLEISHMAN, F . C . Broeman and Co., Cincinnati, Ohio AND
JOSEPH J. KLINGESBERG, Xacier Unicersity, Cincinnati, Ohio IRCONIUM
has recently been found useful as a constituent
Z in aluminum-based alloys. is The phosphate method for the lengthy, requires tedious separadetermination of zirconium (1)
tions, and is subject to error in low zirconium concentration ranges. The alizarin red S colorimetric method is reported to have low tolerance for aluminum ions ( 5 , 6). The success of the mandelate reagents in the determination of zirconium in steels (5, 4 ) suggests that they might be used to advantage in aluminum alloys. Two procedures for the determination of zirconium in aluminum alloys in the presence of copper, magnesium, silicon, iron, manganese, nickel, tin, antimony, chromium, titanium, and vanadium were developed. The first procedure is applicable to alloys containing less than 0.i5% silicon and involves direct precipitation of zirconium viith the mandelate reagents. The second procedure is used for alloys containing more than 0.75% silicon and involves a preliminary separation of zirconium as the hydroxide. A procedure for the simultaneous determination of dicon and zirconium in the same sample is also described. PROCEDURE
Zirconium Determination in Alloys Containing Less Than 0.75Yo Silicon. Three t o five grams of the aluminum sample in a 250-ml. beaker are dissolved in 20 ml. of hydrochloric acid (1 t o l),adding the acid slowly until the vigor of the reaction subsides.
Additional acid may be necessary to complete solution if the sample is larger than 3 grams. When dissolution is complete, 25 ml. of water are added, and the solution is boiled for a few minutes. The solution is filtered through a No. 31 Whatman filter paper to remove any undissolved particles or silicigeneous matter. The volume of the solution is adjusted to about 75 ml. while the acid concentration is maintained at around 15% or less. Eighteen milliliters of a 0.1M solution of p-bromo- or pchloromandelic acid is added with constant stirring. (For amounts of zirconium larger than 0 . 1 % use correspondingly larger amounts of the reagent.) The solution is digested for 20 minutes a t 80 to 85" C., cooled, and filtered through a KO.40
\Thatman filter paper. The precipitate of zirconium halomandelate is washed about 10 times with distilled water. The paper and precipitate are charred slowly and ignited in a platinum crucible a t approximately 1000" C. The final weighing of the zirconium oxide can be performed directly in the platinum crucible or on a tared weighing dish to which the oxide has been transferred.
% zirconium
=
weight ZrO? X 0.7403 X 100 weight of sample
With mandelic acid as a reagent the following procedure is used. Three to five grams of the sample are dissolved with 35 ml. of hydrochloric acid (1 to 2), and the contents are filtered through a No. 31 Whatman filter paper. The filtrate is adjusted to about 100 ml., and the zirconium is precipitated with a saturated solution of mandelic acid (amount depending on the zir-
Table I. Determination of Zirconium in Aluminum Alloys Using Various Reagents Composition of Alloy, % PhosphateQ A1 92 42 (by diff.) 0.06 0.06 c u 4.64
% Fe
Si Cr Zn
1.44 0.62 0.38
0.06 0.06 0.06
p-Chloromandelic acid
0 06 0.06 0 06 0 06 0 06
0.06 0.06 0.06 0 06
..
0.08 0.08 0.08 0.08 0.08
0.08 0.08 0.08 0.08
0.08 0.08 0.08 0.08 0.08
0.06
0.31
p-Bromomandelic acid
.. ..
..
..
0.09
0.04 0.08 0.07 0.08
0.08 0.08
z .
JIandelio acid
Method of Aluminum Co. of America ( 1 ) .
0.08
V O L U M E 2 5 , NO. 1 1 , N O V E M B E R 1 9 5 3
1759
Table 11. Determination of Added Zirconium in Aluminum Alloys ZJsingVarious Reagents Zirconium Found, G r a m Composition of Alloy, %
Zirconium Added Gram'
Phosphate
0.0040 0.0040 0.0040
n-Rromo\ 1and e 11c
acid
6aidilic acid
0.0038 0,0039 0.0036
0 0040 0 0039 0 0038
0.0040 0.0038 0.0038
0.0010 0.0010 0.0010
0.0009 0,0009 0.0008
0 0010 0 0011
0 0008
0,0009 0.0009 0.0010
0.0015 0.0015 0.0015
0.0014 0.0013 0.0014
0 0014 0 0014 0 0014
0.0014 0.0014 0,0014
0.0040 0.0040 0.0040
0,0036 0,0038 0.0038
0 0038 0 0037 0 0039
0.0039 0.0039 0.0040
0.0004 0.0004
0.0004 0,0004
0 0003 0 0004
0.0004
0.0008 0.0008 0.0008
0.0007 0.0007 0.0005
0 0008 0 0007 0 0007
0.0007 0.0007 0.0007
0.0015 0.0015 0.0015 0.0045 0,0045 0,0045
0.0015 0.0012 0.0014 0.0043 0.0043 0.0043 0.0075 0,0076 0.0076 0.0302 0.0304
0 0015 0 0014 0 0015
0.0015 0.0014 0.0013 0.0044 0.0044 0.0043 0.0079 0.0079 0.0079 0.0307 0.0308
0.0080 0.0080 0.0080
0.0310 0.0310
0 0 0 0 0
0044 0043 0044 0078 0078 0 0078 0 0304 0 0304
0.0004
conium content). The zirconium mandelate is filtered on a No. 40 Whatman filter paper with the aid of some paper pulp, the precipitate washed with a warm solution of mandelic acid containing 3% hydrochloric acid, charred slowly in a platinum crucible, ignited, and the zirconium oxide weighed directly in the crucible or transferred to a tared dish and then weighed. The results obtained by these procedures are given in Tables I and 11. In Table I the zirconium was actually present in the alloy. In Table I1 the zirconium was added as a solution of zircony1 chloride after the sample had been dissolved, Zirconium Determination in Alloys Containing More Than Two grams of the aluminum sample in a 250-ml. beaker are dissolved by adding 5 grams of sodium hydroxide pellets followed by 20 ml. of distilled water. The beaker is covered vith a watch glass and placed in a cool water bath until the vigor of the reaction has subsided. If necessary, more distilled water (10 to 15 ml.) may be added. Further dissolution is obtained by warming the beaker on a hot plate. A total of 10 ml. of hydrogen peroxide (3%) is then added, small amounts a t a time, to effect solution of copper and other undissolved metals. The contents are boiled gently for 10 minutes, cooled, diluted to about 150 ml., and filtered on a No. 31 Whatman filter paper after washing any particles adhering on the watch glass into the beaker. Zirconium remains in the filter paper as the hydrous oside. The precipitate is washed well with about 10 small portions of warm distilled water, and the filtrate is discarded. The bulk of the precipitate is washed back into a 250-ml. beaker with about 25 ml. of warm distilled water. Sixty milliliters of warm hydrochloric acid (1 to 3) are then poured on the filter paper, while the funnel is rotated to ensure complete solution of the zirconium. The washings are caught in the beaker containing the bulk of the precipitate. Complete solution of the contents of the beaker is obtained by heating. More acid is added if necessary. The contents are then diluted to about 125 ml., filtered, using a No. 31 Whatman filter paper to remove any residue, and the filtrate is adjusted to a n acidity of 12.5 to 20% with hydrochloric acid in a total volume of not more than 200 ml. Twenty-five milliliters of 0.1 M p-bromo- or p-chloromandelic acid is added with constant stirring. (When the approximate content is known, the 0.75% Silicon.
amount of reagent can be calculated on the basis of theoretical precipitation as the zirconium tetramandelate. Experiment has shown that 16% excess reagent in the case of p-bromomandelic acid is required for complete precipitation. When the zirconium content is unknown, an excess amount can be added as above, or an approximate amount added, and the filtrate can be tested with reagent for complete precipitation.) The contents are digested a t 80 to 85" C. for 20 minutes, cooled to room temperature, and filtered through a No. 40 Whatman filter paper using some paper pulp as an aid. The precipitate of zirconium halomandelate is washed 10 times with distilled water, and the paper and precipitate are charred slowly and ignited in a preweighed platinum crucible a t approximately 1000" C. For ordinary industrial work the zirconium oside after ignition can be transferred to a tared dish for weighing. Results obtained on aluminum alloy samples to which a known amount of zirconium was added are given in Table 111.
Table 111. Determination of Silicon and Added Zirconium in Aluminum Alloys Composition of Alloy, %
Zirconium Added, Gram 0.0004 0.0008
Zn Ti
0.02 0.01
336-SAlloy A1 92.52(by diff.) 4.95 Si Cu 1.40 Fe 0.48 M g 0.46 T i 0.11 M n 0.05 Zn 0.03
0.0011 0.0011 0.0022 0.0022 0.0044 0.0044 0.0150 0.0300 0.0300
Zirconium Found, Gram ____ p-Chlorop-Bromomandelic mandelic Phosphate acid acid
0,0003 0.0007 0.0009 0 0010 0.0020 0.0021 0.0040
....
0.0142 0 0291
....
0 0 0 0
0008 0011 0011 0022 0 0028 0 0028 0 0150
0.0006 0.0011 0.0010 0.0020 0,0027 0.0027 0.0142
0 0015 0 0015 0 0028
0.0014 ..... 0.0025 0.0034 0.0040
0 0036 0 0042 0 0042
0.0004 0.0007 0.0010 0.0011 0,0022 0.0021a 0.0041 0.0041'' 0.0147 0.0297 0.0297a
.....
0.0010 0.00105 0.0021
..... .....
0.0014
..... .....
0.0033 0.0042
0.0040
0 0004 0 0008 0 0010 0 OOlla 0 0022 0 0021" 0 0043 0 0042" 0 0148
0 0298 0 0297a 0 0008 0 0010
0010a 0021 0027 0027a 0 0149 0 0 0 0
0 0 0 0 0 0
0014 0014" 0027 0033 0040 00415
a Silicon determined in same sample by method described.
Simultaneous Determination of Silicon (1, 2) and Zirconium in High Silicon Aluminum Alloys. Two grams of the aluminum alloy sample in a large nickel dish are treated with 5 grams of sodium hydroxide pellets, and 20 ml. of distilled water are added, 10 ml. a t a time. The dish is covered with a watch glass and cooled by means of a water bath until the vigorous reaction has subsided. When the reaction is near completion, 10 nil. of distilled water is used to vash any undissolved particles adhering to the sides of the dish don-n into the sirupy mass. The dish is warmed on a hot plate, and 10 ml. of hydrogen peroxide (3%) are added, small amounts a t a time, to dissolve copper and other undissolved metals. The contents are moderately boiled for 10 to 15 minutes or until they have the appearance of a semipaste. The mass is diluted to 40 ml., and cooled. It is then transferred into a 600-ml. beaker, containing 50 ml. of a mixture of concentrated sulfuric and phosphoric acids (4 to l), which has been rotated to moisten the sides with the acids. Fifteen milliliters of a misture of concentrated hydrochloric and nitric acids in water (1 to 1 to 2 by volume) are then added and the contents taken down to dryness and fumes usin medium heat. Fuming is continued for 10 minutes. After coofing, 35 ml. of water and 10 ml. of concentrated hydrochloric acid are added. The silica is removed by filtration through a No. 40 Whatman filter paper using paper pulp as a n aid. The silica is washed first with warm distilled water, then with hot saturated ammonium sulfate solution to remove lead sulfate, and again with warm water. The filtrate is dehydrated as described above, the silica removed by filtration, and the combined residues are ignited in a platinum crucible after slow charring to remove carbonaceous material. The crucible and contents are cooled, weighed, and then treated with a fern
1760
ANALYTICAL CHEMISTRY
drops of concentrated sulfuric acid and 10 ml. of hydrofluoric acid (48%). This is heated until dry, ignited, cooled, and weighed. The difference in weight represents silica. Any residue left in the platinum crucible is fused with potassium acid sulfate, the mass dissolved in hydrochloric or sulfuric acid (1 to 9), and the contents are added to the combined original filtrates which should have a total acidity of 10 to 20% and a total volume of not more than 250 ml. The required amount of halomandelic acid is now added and the zirconium content of the sample determined as described above. Results obtained by this procedure are given in Table 111. SUMX14RY
Zirconium in aluminum alloys can rapidly and conveniently be determined gravimetrically by the mandelate method. The use of p-chloro- or p-bromomandelic acid is preferred to mandelic acid ( 4 ) . S o significant difference exists between the chloro a n d bromo derivative. These reagents are now available com-
mercially from the H. and S. Chemical Co., 528 Howard St., Buffalo G , S. Y. and Dajac Laboratories, 511 Lancaster St., Leominster, Mass. LITERATURE CITED
( 1 ) Aluminum Co. of America, “Chemical Analysis of Aluminum” (bIethods Standardized and Developed by the Chemists of the
Aluminum Co. of America under the Direction of H. V. Churchill and R. W. Bridges), 2nd ed., New Kensington, Pa., Aluminum Research Laboratories, 1941. (2) Association of Light Oil Refiners, “Modern Methods for the Analysis of Aluminum Alloys” (by a Committee of Chemists Convened by the Association of Light Alloy Refiners), London, Chapman and Hall, Ltd., 1949. (3) Gavioli, G., and Traldi, E., Metallurgia itat., 42, 179 (1950). (4) Klingenberg, J. J., and Papuoci, R. A,, Ari.4~.CHEY.,24, 1861 (1952). ( 5 ) Mayer, 4., and Bradshaw, G., Analyst, 77,476 (1952). (6) Wengert, G. B., ASAL.CHEX.,24, 1449 (1952). RECEIVED fer review .June 24, 1953. Accepted Joly 24. 1953.
Separation of Hydrogen Peroxide from Organic Hydroperoxides Application to Polarographic Analysis of Mixtures WILLIAM M. MAcNEVIN AND PAUL F. URONE McPherson Chemical Loboratory, T h e Ohio State University, Columbus, Ohio of, hydrogen peroxide and certain organic hydroM peroxides have been quantitatively separated. It has been observed in this laboratory that the polarographic wave for hyIXTURES
drogen peroxide can be eliminated entirely, as shown in Figure 1, by complexing the hydrogen peroxide with titanium(IV) ion and precipitating the complex i n alkaline solution. The organic hydroperoxides reported here seem to be unaffected by the complexing ion and by its precipitation. The yellow color formed by reaction of titanium( IV) and hydrogen peroxide is the basis for the colorimetric determination of hydrogen peroxide. According to Schwarz ( 2 , S),the yellow complex formed in sulfuric acid solution hss the formula Ti02The removal of hydrogen peroxide from a mixture of hydrogen peroxide and hydroperoxides by precipitation of the yellow solution xith ammonium h>-dro\;ideseems to be a new application.
The applications reported here involve primarily water-soluble organic hydroperoxides. Some mixed solvents have also been tried rithout adverse effect. Concentrations studied were of the order of 10 - 4 - l f in the solutions measured polarographically. hlivtures of hydrogen peroxide and the following organic hydroperoxides have been analyzed successfully by this method: 3-pentyl hydroperoxide (I-ethylpropyl hydroperoxide, International Union of Chemistry) tert-butyl hydroperoxide, and 3-cyclohexenyl hydroperoxide, cyclohexyl hydroperoxide, and 2,5,5-trimethyl-2-hexyl hydroperoxide ( 1,1,4,4tetramethylpentyl hydroperoxide, the International Union of Chemistry). Data showing the results obtained after the addition of known amounts of hydrogen peroxide are shown in Table I. No failures of the method have so far been observed. The method may also be useful with other combinations of hydrogen peroxide, organic hvdroperoxides. and peroxides. EXPERIMENTAL
Table I.
Recovery of Hydrogen Peroxide
Hydroperoxide Present, M g . 3-Pentyl 0.8 0.4
Hydrogen peroxide, Mg. Added Found 50 52 38 37 25
29 38
0.1 0.4 0.5 0.5
101
36 96
0.5 0.5 0.5
5 50 50
4 53
Cyclohexyl
1.0
50
51
2,5.5-TrimethyI-2-hexyl
0.5 1.0
50 50
52 47
feri-Buty
3-Cyclohexeny
38 38
Polarograms were run with a Sargent Model XX, electronic recording instrument and an H-type polarographic cell (1) connected to a saturated calomel electrode with fritted-glass agar bridge. Ten-milliliter portions of solution were used. The drop time wm of the order 3 to 4 seconds and the value of m was approximately 1.35 mg. per second. The applied voltage was increased a t a rate of 1 volt per 5 minutes.
54
-
Curve I Curve 2 Curve 3
a
-
current with 01 N KCl solution -- Residual Hydrogen peroxide After precipitation wlth Ti4’
50 Polarographic current-voltage curves were measured for solutions containing both hydrogen peroxide and organic hydroperoxide. Titanium ion was added as titanium dioxide dissolved in 1 S hydrochloric acid, which produced a slightly acid solution The titanium was precipitated with a slight excess of ammonium hydroxide. The current-voltage curve was then repeated. The decrease in wave height as shown in Figures 1 and 2 is due to the precipitation of hydrogen peroxide. The remaining mive in Figure 2 is due to the organic hydroperoside.
E I-
5
? u3
I
3 1
03
06
09
12
I
15
1
18
I
21
Voltoge
Figure 1. Current-Voltage Curves for Hydrogen Peroxide before and after Treatment with Titanium Ion
