STABILITY CONSTANTS OF METALPICOLINATES
Feb., 1957
229
With the aid of eq. 7.2.11 and 3.2.24 we finally obtain /
q* =
2(i; 480~
-4
2 Np2pp(l-
\
(7.2.12)
-&&Y~-~,)
P = 2
where we have used N1 = W f i . This is clearly proportional to the square root of the total concentration of the solution. For the case of complete confluence, Le., WI = w2 = . . = wI = o we have proved that
.
N1 = Ns =
...
3
Ns
E
where we have used
0
which leads to the result previously obtained by Onsager and FUOSS~ (7.2,13)
Acknowledgments.-One of us (S.K.K.) wishes to thank the United States Government for a Smith-Mundt Grant and Yale University for a Sheffield Scientific School Fellowship. Appendix 1. Successive Reduction of the Fundamental Equation If we know one of the roots of the algebraic eq. 6.1.1 we can reduce the degree of the equation by one. Denoting by OLk2 the known root we have from eq. 6.1.1
4
2 I
ti
1
(Wiz
- ak2)
-0
Now, we introduce a set of pseudo-transference numbers
t*i
defined by
then, t*i may be positive or negative but still are normalized to unity as
Thus, eq. 6.1.1 becomes (4)
which is the required result. We repeat the procedure until we reach a quadratic equation.
STABILITY CONSTANTS OF PICOLINIC AND QUINALDIC ACID CHELATES OF BIVALENT METALS BY KEINOSUKE SUZUKI, MOTOO YASUDA AND KAZUO YAMARAKI Contribution from Chemical Institute, FacuEty of Science, Nagoya University, NaGoya, Japan Received July 8, 1966
Stability constants of picolinates of nickel, zinc, cadmium and lead were determined by the p H method and also that of copper picolinate by the photometric method. The values of log K found were Cu 16.0, Ni 11.9,Z n 9.42,Pb 7.88 and Cd 7.54. Many metals form precipitates with quinaldic acid; the stability constants of only lead and nickel were determined by p H method.
The chelates of picolinic acid and copper or iron were first reported by Weidel,' followed by Ley's studies2 on chelates of chromium and cobalt. Recently Shinra3determined t,he absorption spectra of ferrous chelate and applied the results to colorimetric determination of iron. H e also found that quinaldic acid forms colored complexes with iron. The present study is concerned with the stability constants of picolinic acid chelates, formed by bivalent metals such as Ni, Zn, Cd, P b which were determined by the p H method and also the stability constants of copper picolinate, determined by the spectrophotometric method. While many metals form precipitates with quinaldic acid, stability constants of only lead and nickel can be determined by the p H method. (1) H. Weidel, Ber., 12, 1989 (1879). (2) H.Ley and K. Ficken, ibid.. 50, 1123 (1917).
(3) K. Shinra, K. Yoshikawa, T.Kato and Y.Nomizo, J . Chem. SOC. J a p a n , Pure Chem. Sect., 78, 44 (1954).
Experimental (1) .Reagents.-Picolinic acid was prepared by oxidation of a-picoline.4 uinaldic acid5 was prepared by hydrolysis of w-tribromoquina dine, formed by bromination of quinaldine. Metal nitrates of reagent grade were used. (2) Procedure of the pH Method.-Solutions containing the following concentrations of nitrates of the respective metals and picolinic or quinaldic acid mere prepared and were titrated with standard NaOH or HNOa a t 25': Cd(NO&, 0.0013M ; Pb(NOa):, 0.0010-0.0020 M ; Zn(NO+, 0.0013 M ; Ni(NOa)z,. 0.0006-0.0011 M ; icolinic acid, 0.001-0.01 M ; quinaldic acid, 0.0005-0.005 The ionic strength of the solutions was maintained a t 0.1 by adding KNOa. A glass electrode combined with an electronic amplifier was employed for the determination of pH and standardized against standard buffers. For the first acid dissociation constant of picolinic acid, the value of pK, 1.60 reported by Jellinek and Urwine was used, and for quinaldic acid we adopted the results of Wen-
B
5.
(4) A. W. Singer and 8. M. MoElvain. Org. Syntheses, 20, 79 (1940). (5) D.L. Hammick, J . Chem. Soc., 128,2882 (1923). ( 6 ) H. H. 0.Jellinek and J. R. Urwin, Tms JOURNAL, 58. 548
(1954).
230 TITRATION
MOTOOYASUD.4
'IiEINbSUI
