V O L U M E 28, NO. 1 2 , D E C E M B E R 1 9 5 6
2019 it will be successful to a predetermined extent. As an added advantage, it may be possible t o predict qualitatively or semiquantitatively the behavior of other similar contaminants without actual experimentation. The limiting factor with regard to general application, h o w ever, is the fact that in many cases the type of coprecipitation may be such that neither distribution law is followed, because coprecipitation is nonsystematic or the systematic distribution is something intermediate between logarithmic and homogeneous distribution. ACKNOWLEDGMENT
I 98 0
98 5
I
I
990
99 5
I00
%THORIUM P R E C I P I T A T E D
Figure 4. Comparision between experimental rate of increase in coprecipitation and that calculated for an average value of X for praseodymium
the variation between extent of precipitation of thorium and extent of coprecipitation of rare earth for two theoretical cases which show a X type of distribution, with X equal to the average value of lanthanum (Figure 3) and praseodymium (Figure 4) as given in Table 11. Actual coprecipitation data have been superimposed on these theoretical curves t o illustrate the extent of agreement. The application of coprecipitation theory in general areas such as this can serve as a very useful tool. Where a separation is good but not quite good enough, it can tell first of all whether or not the contaminant carries bj- systematic replacement or by some nonsystematic means such as adsorptibn. If the coprecipitatiori is systematic, it will tell whether the maximum possible separation is being achieved-i.e., whether the distribution is logarithmic Finally, once the nature of the systematic distribution has been established, the process of precipitation can be controlled to achieve any predetermined purity in the precipitate. A tm-0-step precipitation process (11) can be designed with assnrance that
The author is pleased to acknowledge the helpful suggestions and encouragement offered by Murre11 L. Salutsky during the course of this work and is also indebted to H. \Ir, Kirby for assistance with the radiochemical techniques employed. LITERATURE CITED
Doerner, H., Hoskins, W., J . Am. Chem. SOC.47, 662 (1925). Gordon, L., ANAL.CHEM.27, 1704 (1955). Henderson, L., Kracek, F., J . Am. Chem. Soc. 49, 738 (1927). Rankama, K. K., Sahama, T. G., “Geocheniistry,” pp. 103-28, University of Chicago Press, Chicago, Ill., 1950. Salutsky, M. L., Kirby, H. W.. ANAL.CHEM.26, 1140 (1954). Ibid., 27, 567 (1955). Schlyter, K., Arlziv Kemi 5, 61-71 (1952). Stine, C. R., Gordon, L., ANAL.CHEM.25, 1519 (1953). Stine, C. R., Gordon, L., U. S. Atomic Energy Comm., NYO3188 (1953). Wahl, A. C., Bonner, N. A., “Radioactivity Applied to Chemistry,” pp. 104-22, Wiley, New York, 1951. Willard, H. H., Sheldon, J. L., ANAL.CHEM.22, 1162 (1950). Zachariasen, W. H., “Crystal Chemistry of the 5f Elements.” Chap. 18, “The Actinide Elements,” Seaborg, G. T., Katz. J. J., Ed., NNES IV-l4A, pp. 775-6, LIcGraw-Hill, New York, 1954. RECEIVED for review December 9, 1955. Accepted July 6, 1956. Division of Physical and Inorganic Chemistry, 125th Meeting, ACS, Kansas City, March-April 1954. Mound Laboratory is operated b y Monsanto Chemical Co. for the U. S. Atomic Energy Commission under Contract Number AT-33-1-GEN-BR.
Determination of Zirconium and/or Hafnium Using 1-Naphthylglycolic Acid R. B. HAHN and P. T. JOSEPH’ Chemistry Department, W a y n e University, Detroit 2, Mich.
M
specific reagent for the precipitation of zirconium (or hafnium I because of the presence of the zirconium-binding - CH( OH)COOH group. Although glycolic acid contains this group, the reaction is not quantitative, because of the absence of the weighting effect of the phenyl group. It was expected, therefore, that the substitution of a group like naphthyl in place of the phenyl group of mandelic acid would produce an effective reagent for zirconium. Oesper and Klingenberg (7) prepared a number of such substituted compounds, including 2-naphthylglycolic acid, and studied their reactions with zirconyl ions. Because l-naphthylglycolic acid has not been studied previously, this investigation was undertaken.
1 Present address, Titanium Alloy Division, National Lead Co., Niagarn Falls, N. Y .
The acid was prepared by treating 1-naphthyl magnesium bromide with chloral and hydrolyzing the resulting product ( 6 ) . The acid was purified by steam distillation and recrystallization from water. The product was obtained as white needle-shaped
Bath zirconium and hafnium are precipitated quantitatively from dilute acid solution by 1-naphthylglycolic acid. No interference is caused by aluminum, ferric, lanthanum, stannic, thorium, titanium, and uran! 1 ions. The method was tested by the analysis of a zircon are. The results obtained using 1-naphthylglycolic acid compare favorably with those obtained with mandelic acid.
ANY organic compounds have been used for the determination of zirconium (8-10). The most specific reagents are phenylglycolic acid (mandelic acid) and other derivatives of glycolic acid. These reagents, however, do not differentiatr between zirconium and hafnium, both of which are precipitated quantitatively ( 2 ) . According to Feigl ( I ) , mandelic acid is :I
PREPARATIOK OF 1-NAPHTHYLGLYCOLIC ACID
ANALYTICAL CHEMISTRY
2020 crystals, melting a t 97-98" C. Reported values for the melting point are the same (6). An over-all yield of 26y0 was obtained. ANALYSES. C12H1003requires C, 71.29; H,4.95; found C, 71.22; H, 4.91. 1-Naphthylglycolic acid is only slightly soluble in water; hence the sodium salt was prepared in order t o increase the solubility. EXPERIMENTAL
Solutions. A 0 . l M solution of the sodium salt of l-naphthylglycolic acid was prepared as stock solution. Stock solutions of zirconium oxychloride and hafnium oxychloride were prepared by dissolving the chemically pure salts in 0.1V hydrochloric acid. The solutions were standardized with mandelic acid, using the method of Kumins ( 5 ) , and with cupferron, using the method of Hillebrand and Lundell ( 4 ) . The results given in Table I are averages of duplicate determinations.
Table I.
Standardization of Solutions
Reagent Used Mandelic acid Cupferron 1-Kaphthylglycolic acid (sodium salt)
ZrOz, G.
HfOz,
0 0825 0 0824 0 0826
0,4875 0 4876 0 4877
tion is obtained and no precipitate is formed. This behavior resembles that of zirconium tetramandelate, in which an inner complex salt is formed (3). Precipitation of Hafnium. Standard solutions of hafnyl chloride mere treated with the sodium salt of 1-naphthylglycolic acid, using the procedure outlined for zirconium. ii 30-minute period of digestion a t 85" C. was required for the complete precipitation of the hafnium. The precipitate was filtered, washed, dried, and ignited in the same manner as the zirconium precipitate. The results, which are averages of duplicate determinations, are given in Table I. The effect of varying the acidity was found to be the same for hafnium as for zirconium (Table 11). The effect of foreign ions upon the determination of hafnium is summarized in Table 111. These results are averages of duplicate determinations. The reactions of hafnium 1-naphthylglycolate with solutions of sodium hydroxide and ammonium hydroxide are the same as those of zirconium 1-naphthylglycolate.
G.
~ _ _
~
Table 111. Effect of Diverse I o n s Ion Added, Ion .4dded
G.
,4 n-ash solution containing 0.5% sodium salt of l-naphthylglycolic acid and 2% hydrochloric acid was prepared. Procedure for Precipitation of Zirconium with I-Naphthylglycolic Acid. Ten milliliters of the standard solution of zirconyl chloride containing the equivalent of about 0.1 gram of zirconium oxide was mixed with 5 ml. of 1 2 X hydrochloric acid and 5 ml. of distilled water. To this was added 25 ml. of the stock solution of the sodium salt of 1-naphthylglycolic acid. A white precipitate formed immediately. The mixture was digested on a water bath at 85" C. for 20 minutes. The precipitate settled rapidly and was filtered, using Whatman No. 40 filter paper. After filtration, the precipitate was washed with the wash solution mentioned above, then with 95% ethyl alcohol, and finally with acetone, and dried. The dry precipitate was ignited in a platinum crucible t o constant weight of zirconium oxide. The results given in Table I are averages of duplicate determinations.
T a b l e 11. Acid HC1 His04
a
Acid Concn.. A' 0 1 0 3 0 5 0 36 1 08 1 80 2 52
Effect of Acidity ZrOj
ZrOi Taken,
F0und.Q
G.
G.
0 0 0 0 0 0 0
0825 0825 0825 0825 0825 0825 0825
0 0 0 0 0 0 0
0824 0824 0821 0824 0824 0823 0820
Difference,
G. -0 -0 -0 -0 -0 -0 -0
0001 0001 0004 0001 0601 0002 0005
Average of duplicate determinations.
Aluminum(II1) Lanthanum(II1) Iron(I1Ij Titanium(1T) Uranium(V1) Thorium (IT) Tin(1V)
0.1
G.
On Zirconium 0,0825 0,0825 0.0825 0.0825 0.0825 0.0825 0.0825
ZrOz
Difference,
Found,
G.
0 0 0 0 0 0 0
G.
+o +O
0826 0827 0828 0879 0826 0824 0826
0002 0001
+ O 0003 + O 0004
+o
0001 -0~0001 +o 0001
On Hafnium Iron(II1) Aluminum(II1) Titanium(IT1 Thorium (I T)
0.1'
0 1 0.1 0 1
HfOz
HfOz
0.4875 0.4875 0.4875 0.4875
0.4877 0 4877 0.4878 0.4873
+O 0002
+0.0002 4-0 0003 -0,0002
Determination of Zirconium Plus Hafnium in Travancore Zircon. Powdered zircon was opened by borax fusion and converted t o zirconyl chloride by the usual methods (9). The zirconium plus hafnium \vas determined by precipitation with mandelic acid and with the sodium salt of 1-naphthylglycolic acid. The results, given in Table IV, show good agreement between the two methods.
Table IV.
Analysis of Travancore Zircon
+
Zircon,
G.
Effect of Acidity. ;is the acid strength plays an important and often critical role in effecting complete precipitation, the influence of varying the acidity was investigated. The mme procedure was used in each experiment but the acid strength xvas varied. The weight of zirconium oxide formed by igniting the precipitate was determined (Table 11). Interference of Other Cations. Because zirconium usually occurs along with compounds of iron, aluminum, titanium, and rare earths, the possible interference of these and other ions was studied. Sitrates or chlorides of the cations were used for this purpose. Ten milliliters of the standard zirconyl chloride solution was mixed with known amounts of the cation and the zirconium was precipitated according to the procedure described before. The results of these separations are given in Table 111. Masking Action. Zirconium 1-naphthylglycolate dissolves in sodium hydroxide, but a precipitate of zirconium hydroxide quickly forms. With ammonium hydroxide, horn-ever, a solu-
0.1 0 1 0 1 0.1 0.1 0.1
ZrOz
Taken,
1
Reagent Mandelic acid
1
I-Xaphthylglycolic acid
ZrOz HfOz Found G. % 0.6508 65.08 0.6509 65,09 0.6498 64.98 0.6501 65.01
+
Zr Hf Found G. % 0.4812
48.12
0.4808
48.08
Comparison of I-Naphthylglycolic Acid with Other Reagents. The precipitate of zirconium 1-naphthylglycolate is more voluminous than the corresponding mandelate and p-bromomandelate precipitates. I n this respect it is probably inferior to mandelic acid and p-bromomandelic acid as Q reagent for zirconium. The properties of the 1-naphthylglycolate and the 2-naphthylglycolate, as described by Oesper and Klingenberg ( 7 ) , are practically identical. The reagent is more selective than cupferron and the precipitate is more compact than the corresponding cupferrate. LITERATURE CITED
(1) Feigl, F., "Chemistry of Specific, Sensitive and Selective Reactions," pp. 213-16, Academic Press, Ken. York, 1949.
V O L U M E 2 8 , NO. 1 2 , D E C E M B E R 1 9 5 6
2021
(2) Hahn, R. B., ; ~ X A L .CHEM.21, 1579-80 (1949). (3) Hahn, R. B.. 'A-eber, L., J . A m . ChenL. Soc. 77, 4777 (1955). (4) Hillebrand, W.F., Lundell, G. E. F., "Applied Inorganic Analysis," Wiles, New York, 1929. (5) Kumins, c. -1.. *kh..
