SIR: Of the possible explanations offered by Mitaner l ; ~account for the observed decomposition of oxygenated terpenes during gas chromatography, number two would appear most feasible in explaining our observations. The injector could have '3een inadvertently contaminated with s,cidic material because organic acids were present in the flavor concentrate of loganberry. Residual acids in the injector then could
have been responsible for catalytic decomposition of the authentic a-terpineol shown h Figure 2, chromatogram A , of the earlier Correspondence [(ANAL. CHEM.34, 869 (1962)l. It is somewhat easier to maintain the injector free of catalytic when working with relatively pure oxygenated terpenes, but one is faced with possible decomposition when analyzing a complex flavor mixture; hence, the purpose of our earlier Correspondence.
When using packed columns, we have been able to overcome the decomposition problem by means of direct injection of the sample onto the top of the packing. E. A. DAY P. H. MILLER
Department of Food Science and Technology oregon S t a h University Corvallis, Ore.
Equilibrium Distribution of Metal-Fluoride Complexes SIR: Although excellent compilations of successive stability constants of metal-ion complexes are available (4, 19), obtaining specific information from these data can inirolve tedious and troublesome calculations. For practical purposes diagrammatic representation is usually more useful (12); and consequently, we are compiling equilibrium data for the formation of metal complexes with inorganic ligands in the form of distribution diagrams (fraction of each species present us. ligand concentration), with the necessary calculations and plotting performed by means of a high-speed computer. Diagrams of the metal-fluoride complexes are shown here. For the analytical chemist, these plots have the advantages that one can tell at a glanc. the ligand concentration that can be tolerated before complexation of a metal ion begins, and
the species actually present in a solution at a given ligand concentration. These diagrams can also serve as a guide for the preparation of solutions containing a desired species which might be useful-for example, in ion exchange separations or the extraction of ion association compounds. While we have attempted to use some judgment in selecting the stability constants to calculate the diagrams (Table I), they may not be the best ones. The comments by Sillen (16) concerning the methods employed in obtaining the data, and the reliability of same, compiled in reference (4) are worth noting in this respect. We have not, however, used any constants which are obviously inconsistent with the majority of other reported results. Data reporting six constants were usually chosen over data reporting fewer con-
log I F - ]
1.
4.
Berylliurn fluoride
Aluminum fluorlde
Figures 1-6.
stants, and data reported a t zero ionic strength were not considered. In oases where fewer than three complexes are formed, the distribution calculations are relatively simple and have not been plotted at this time. The calculated distribution diagrams shown in Figures 1-14 may be in error a t the higher fluoride concentrations because they have been carried beyond the concentrations that were actually used in determining the constants, and additional complexes may be formed which have not yet been reported. For details, the original work should be consulted. The z-axis can be converted to a log [HF]/[H+] scale by adding 2.9 to the log [F-] values (log [HF]/ [H+] = log [F-] pK,). Curves for Hf+', Y+a, and TiO+* were plotted by the computer, while the others were plotted manually from computer data.
+
+
log I F - ]
log [ F - I
2.
Vanadyl fluoride
3.
Uranyl fluoride
5.
Gallium fluoride
6.
Indium fuoride
Calculated equilibrium distribution diagrams of metal-fluoride complexes VOL. 36,
NO. 1 ,
JANUARY 1964
243
I
‘ 3
< 0c3
0 BOO
0 600 0
L
I 0.400
0.200
0
-2
-3
-60
-7
-6
-5
-4
-50
log [F-I
7.
-43
-33
-,
-IO
-20
8.
Scandium fluoride
-3
-2
-3
.-
-6
3
-40
log IF-1
log [F-I
Yttrium fluoride
9.
Chrornium(1ll) fluoride
4C
ca z
06
:04
Z
-3
-4
-5
-6
-7
-2
log IF-1 I
0
-2
-1
-3
-4
-5
-60
-6
-5C
loo IF-]
-40
-30
12.
-20
Zirconium fluoride
-IO
loo IF-]
10. Ferric fluoride
11.
LITERATURE UTED
Titanyl fluoride
(1) Ahrland, S., Larsson, R., Roeengren, K., Acta Chem. Scund. 10,705 (1956).
06CO
A0400
-IC0
-90
-EO
-70
-60
-53
-40
log IF-1
13.
Hafnium fluoride
Figures 7-1 4. complexes
Table 1.
Calculated equilibrium distribution diagrams of metal-fluoride
Stepwise Formation Constants of Fluoride Complexes
Log K 3 4 3.56 1.99 VO+’ 1.70 0.33 uo,+* 2.57 1.34 Al+a 3.85 2.74 Ga+y 2.75 1.52 In 2.34 1.10 527 4.07 2.85 3.20 3.20 (3.91) CrCa 3.34 2.48 Fe+8 4.46 3.22 2.00 Ti0 +’ 4.35 3.96 3.72 ZrC4 8.80 7.32 5.82 4.85 Hf+‘ 8.16 6.94 6.24 6.04 Th+‘ 7.65 5.81 4.51 a IiNO, for Al(III), others NaC10,.
Cation Be+’
:?:
244
1 5.89 3.20 4.54 6.13 4.52 3.70 6.18 3.93 4.36 5.30
2 4.94 2.18 3.34 5.02 3 80 2.56
ANALYTICAL CHEMISTRY
5
6
T 20
1.63 0.30
0.47
0.36 4.65 4.82
3.98 5.81
20 25 20 20 25 25 25 25 25 25 25
‘p
Var.
Reference (10)
1
(@
1 0.53
!I)
Var.
1 0.5 0.5 0.5 Var. 3 2 3 0.5
(6)
(If) (16) (13) (14) (18)
(9) (7) (6,8)
(17) (9)
(2) Ahrland, S.,Noren, B., Ibid., 12, 1595 (1958). (3) Babko, A. K., Kleiner, K. E., Zh. Obshch. Khim. 17. 1259 (1947). (4) Rjerrum, J., ‘ Schwarzenbach, G;I Sillen, L. G., “Stability Constants, Part 11, The Chemical Society, London, Spcc. Publ. No. 7 (1958). ( 5 ) Brossett, C., Orring, J., Svensk. Kem Tidskr. 55, 101 (1943). (6) Buslaev, Y.A., Zh. Neorgan. Khim. 7. 1206 (1962). (7)‘Caglioti, V.;Ciavatta, L., Liberti, A., J. Znorg. Nucl. Chem. 15, 115 (1960). (8)Connick, R. E.,McVeg, W. H., J. Am. Chem. SOC.71, 3182 (1949). (9) Dodgen, H.W., Rollefson, G. IC,Zbid., 71, 2600 (1949). (10)Kleiner, K. E.,Zh. Obshch. Khim. 21, 18 (1951). (11) Kleiner, K. E.,Gridchina, G. I., Zh. Aleorgan. Khim. 5 , 202 (In6O). (12) Kolthoff, I. M., Elving, P. J. (eds.)! “Treatise on Analytical Chemistry, Part I, Vol. 1, p. 277, Interscience, New York, 1959. (13) Kury, J. W., Paul, A. D., Hepler, L. G., Connicqk, R . E., J . Am. C h a . SOC.81, 418.5 (3959). (14)Paul, A. D., Gallo, L. S., T’anCamp, J. R., J. Phys. Chem. 65, 441 (1961). (15) Sillen, I,. G., J. Znorg. Nzd. Chrm. 8,176 (1 958). (16) Sunden, N., Svensk. Krm. Tidskr. 6 6 , 50 (1956). (17)Varga, L. P.,Hume, D. K.,Inorg. Chem. 2, 201 (1968). (18)Wilson, A. S.,Taube, H., J . 4 m . Chem. Soc. 74,3509 (1952). (19) Yatsimirskii, K. B.,T‘adev 1‘ 1’ , “Instability ,, Constants of bomplex Compounds, Pergamon, London (1960). GERALD GOLDSTEIN Analytical Chemistry Division Oak Ridge National Laboratory Oak Ridge, Tenn.
