Gowda, H. Sanke

Ramappa, P. G.

English

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INDIAN J. CHEM .• VOL. 1-4A. JUNE 1976TAB1.E 1 - PROTON-LIGAND FORMATION CONSTANTSot 5.6'-DICARBOXY-4-HYDROXYAZOBENZENEAND FORMATIONCONSTANTSOF ITS METAL COMPLEXESCation 10& tc, log K, log s,I II III Av. I II III Av. I II III Av.H.f: 13,19- 4010 4010 4013 H1 2'09 2'09 2'09 2'09Zn(lI) 13·10 13-20 13·26 13-19 10'10 10·10 10'00 10..07Cu(U) 12'50 12-50 12'51 1HO 5'S0tNi(ll) 9·80 10'00 9·98 9'92 7·40 H() 7'40 NOCo(lI) 9·10 9·20 9'36 9'22 6·90 6·90 6·89 6·89,- it t-I = half integral method. II = linear plot method. III = pointwise calculations method.-Obhined from nH = 1. tObtained from n = 1.iiFig. 1 - Formation curves for the metal complexes of5,6'-dicarboxy-4-hydroxyazobenzeneof 6-carboxy group and nitrogen of the diazogroup. The pH-metric titration indicates the possi-bility of complexation through oxygen atoms of the4-hydroxy and 5-carboxy groups. However, thedissociation of protons from 6' -carboxy group cannotbe ruled out. Though 6'-carboxy group is notinvolved in complex formation, the number of re-placeable hydrogens are three. This is in accordancewith Irving-Rossotti method where the term Yembodies all the replaceable hydrogens, throughcomplex formation or self-dissociation. The termfiH indicates the actual number of hydrogen atomsattached per ligand molecule at a particular valueof B and which get replaced as a result of complexformation. The possibility of the complexationthrough 4-hydroxy and 5-carboxy groups findsfurther confirmation from the work of Drew andFairbaim-P who have staled that in the case ofazo-salicylic acids, coordination of metal throughazo-nitrogen is not possible.The authors thank Prof. M. M. Bokadia forproviding necessary laboratory facilities and theCSIR. New Delhi, for the award of a junior researchfellowship to one of them (D.P.C.R.).References1. RUIGH WM. L.. J. Am. chem. Soc., 51 (1929). 1456.2. ENGEL. E. W., J. Am. chem, Soc., 52 (1930), 1812.3. NORRIS, SHERVE, R .• SWANEY,M. 'V. & RIECHERS, E. H .•J. Am. chem. Soc .• 65 (1943). 2241.4. BAILAR J. C. & CALLIS. C. F., J. Am. chem. Soc .• 74(1952), 6018.5. CALLIS, C.F .• (NIELSEN, N. C. & BAILAR, J. C., J. Am.chem. Soc., 74 (1952), 3461.4546. B]ERRUM. J .. Metal ammi1te formatio« in aqueous solu»tiMI (P. Haase ct Son. Copenhagen). 19-41, 20.7. IRVING. H. M. & ROSSOTTI.H. S., J. che",. Soc., (195-4).2904.8. KHADIKAR.P. V. & AMERIA.R. L.. J. Indian chene. Soc.,49 (1972). 33.9. KiiADIKAR, P. V. & KAltKAR, S. N., Indian J. Che;r..•11 (1973), 1198.10. KHADIKAR, P. V. & KAKKAR. S. N .• Indian J. Che"".•(in press).11. BRAUDE,E. A. & NACHOD,F. C., Detel'mination of organicstructure by physical methods (Academic Press, NewYork), 1955, 629.12. IRVING, H. M. & WILLIAMS, R. J. P., Natul'e (Lond.),162 (1948), 746.13. DREW. H. D. K. & FAIRBAIRN,R. E., J. chem. Soc .• (1939).823.Spectrophotometric Determination of Pd(U)using Prochlorperazine Maleate as ReagentH. SANKE GOWDA& P. G. RAMAPPADepartment of Postgraduate Studies & Research in ChemistryManasa Gangotri University of Mysore, MysoreReceived 28 June 1975; accepted 15 September 1975Prochlorperazine maleate forms a red coloured 1 : 2(metal-ligand) complex with Pd(II) in the pH range0·1 to 3·0. Beer's law is obeyed in the range of 0·2 to12 1111 Pd(II) with am olar extinction coefficient of 4·63x10' litre mole'? CDl-1 at 480 nm. The apparent stabilityconstant of the 1 : 2 complex at pH 1'4 is lOll... The in-fluence of some common ions is reported.THE colour reaction between prochlorperazinemaleate (PPM) and Pd(II) was employed forthe identification of PPMl-3. The present paperdescribes the results of study of complex formationand a method for the determination of Pd(II).PPM forms a red-coloured complex with Pd(II)instantaneously at room temperature, the stabilityof which depends on the PH of the reaction medium.Maximum absorbance was achieved in the PH range0·1-3·0 for a solution containing 125 fl.g of Pd(II)and 5 ml of 0·1% PPM. A white turbidity or pre-cipitate was formed, if the PH of the medium wasabove 3·5. The hydrochloric acid-sodium acetatebuffer of pH 1·4 was chosen for all further work.The volume of the buffer solution has no effecton the absorbance of 5 W~Pd(II) solution over ther0.----.range 3-8 ml. The order of addition of reagents wasnot critical. The colour intensity remained practi-cally unchanged up to 60°. The development offull colour takes place immediately after mixing thereagents and remained constant thereafter for about75 min. It was found that a five-fold molar excessof the reagent over Pd(II) was required in order toobtain maximum absorbance.Beer's law was valid over the Pd(II) concentrationrange 0·2-12 [Jog. The optimum concentration rangeevaluated by Ringbom's method+" was 0'8-11 [Jog.Errors were in general ± 1%. A molar absorptivityof 4·63 X 103 litre mole! cm! was obtained at 480 nm.The sensitivity of PPM is more than that of 8-mer-captoquinoline", methylglyoximc"- 7, salicylaldoximes-?and diethazinc hydrochlorides which have been pro-posed as sensitive spectrophotometric reagents forPd(II). The sensitivity of PPM is less than that ofphenyl-a-pyridylketoxirne''- 7, pyridine- RBE9, p-nitro-sodirnet hylaniline" and 1,lO-phenanthroline- RBE9.The method of Vosburgh and Cooper'? was usedto find out the number of complexes formed underthe experimental conditions of the study. Onlyone sharp maximum was obtained around 480 nmin each case indicating the presence of only onecomplex. The red complex exhibits absorptionmaximum at 480 nm. The reagent does not absorbat this wavelength. All subsequent studies wereperformed at 480 nm.A stock solution of Pd(II) was prepared by dis-solving 1 g of Pd(II) chloride (MIs johnson Matthey)in 500 ml of l'OM hydrochloric acid and standardizedgravimetrically by the dimethylglyoxirnc rnethod--.Working solutions were made by suitable dilutionof this solution.A stock solution of PPM (Mis Sandoz Ltd, Switzer-land) was prepared by dissolving 0·25 g of PPM in250 ml of 0·1 M hydrochloric acid and was standard-ized by the eerie sulphate method-s. This was storedin an amber coloured bottle in a refrigerator.Beckman model DB spectrophotometer withmatched 1 ern optical cells was used for absorbancemeasurements. The PH of the solutions was measured(vs SCE) w.th a pH meter model Ll-lO (MIs Elec-tronic & Industrial Instruments, Hyderabad).Recommended procedure for colorimetric determina-tion - The sample solution containing 5-300 [J.g ofPd(U) was transferred to a 25 ml volumetric flask.To this was added 5 ml of 1M hydrochloric acid-I Msodium acetate buffer of pH 1·4 ami 5 rnl 0·1 % PPMsolution ancl the solution diluted to the mark withdoubly distilled water. The solution was mixedthoroughly and the absorbance measured at 480nrn against a corresponding reagent blank. ThePd(lI) concentration of the sample solution wasrcaJ directly from a calibration curve.Effec: of diverse ions - Solutions of <live~se ionsof suitable concentrations were prepared using ana-lytical grade reagents. The following amounts ([l.~per ml) of foreign ions were found to give less than2% error in the determination of 5 [J.g of Pd(lI) perml: osmium(VIII), 10; platinum (IV) , 4; ruthenium(III), 1; rhodium(III), 5; iridium(III), 8; iron (III),2; coba1t(II) , 80; nickel (II) , 550; copper(II), 850;fluoride, 450; chloride, 800; bromide, 230; iodide,NOTES0·5; nitrate, 1640; sulphate, 560; phosphate, 700;acetate, 720; oxalate, 600; citrate, 1600; tartrate,1150 and EDTA, 2. Ag(I), Au(III) and thiosulphateinterfere at all concentrations and, therefore, notolerance limits could be determined.Composition of the Pd(II)-PPM complex - Job'smethod of continuous variation13,14 and mole ratiomethod= were employed to establish the compositionof the complex. The composition determinationswere made in a medium of constant ionic strength(O·lM sodium nitrate) at apR value of 1·4±0·1 anda temperature of 27° ± 1°. The absorbance valueswere measured at 480 nm. The results indicatedthe formation of 1:2 complex between the metaland the reagent.The apparent stability constant values of thecomplex calculated from the absorbance data by(a) method of Foley and Anderson-" modified byMukherji and Dey17 and (b) mole ratio method-swere 11·2 ± 0·1 and 11·0 ± 0·1 respectively.References1. VECERKOVA, J., SULCOVA, M. & KACL, K., Pharmasie, 17(1962), 22.2. YUNG, D. K. & PERNAROWSKI, M., J. phurm, su., 52(1963), 365.3. BLAZEK, J. & PINKASOVA, M., Gesk. Farm., 17 (1968), 181.4. RINGBOM, A., Z. analyt. Chem., 115 (1938), 332.5. AYRES, G. H., Analyt. cu-«, 21 (1949), 652.6. BEAMISH, F. E., The analytical chemistry of the noblemetals (Pergamon Press, Oxford), 1966, 437.7. BEAMISH, F. E., Talanta, 12 (1965), 743.8. SANKE GOWDA, H. & RAMAPPA, P. G., Indian J. cu-«,13 (1975), 418.9. DANGALL, R. M., EL-GHAMRY, M. T. & \VEST, T. S.,Talanta, 15 (1968), 1353.10. VOSBURGH, W. G. & COOPER, G. R., J. Am. chem. Soc.,63 (1941), 437.11. VOGEL, A. 1., A text book of quantitative inorganic analysis(The ELBS & Longmans, London), 1968, 512.12. BASINSKA, H. & NOWAKOWSKI, K., Acta Pol. Pharm., 29(1972), 459.13. JOB, P., Ann. cu«, 9 (1928), 113.14. IRVING, H. & PIERCE, T. B., J. chem, Soc., (1959), 2565.15. YOE, J. H. & JONES, H. L., Ind. Engng cu«: (Anal. ~dn),16 (1944), 111.16. FOLEY, R. T. & ANDERSON, R. C., J. Am. chem, Soc., 70(1948), 1195; 71 (1949), 909.17. MUKHER]I, A. K. & DEY, A. K., Analyt. chim. Acta, 18(1958), 324; J. inorg, nucl. cs-«, 6 (1958), 314.Thiobeneoylacetone as an Extracting &Colorimetric Reagent for Ni(I1)M. V. R. MURTI & S. M. KI!OPKARDepartment of Chemistry, Iridian Institute of TechuologyBombay 400076Received 7 June 1975; accepted 5 September 1975Thiobenzoylacetone can be used for the simultaneousextraction and direct spectrophotometric determina-tion of Ni(U). Ni(U) can be extracted in the pH range8'8-9-4 as a red coloured complex and measured spec-trophotometrically at 500 nm. The Beer's law is validin the concentration range 0·5-10 I1g/ml of Ni(U). Thecomplex is stable for 120 hr. 10 ml of 10-3M reagent isadequate for quantitative extraction. Ni(II) can beselectively separated from mixture containing a largenumber of cations and anions.455

Spectrophotometric Determination of Pd(U) using Prochlorperazine Maleate as Reagent

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Spectrophotometric Determination of Pd(U) using Prochlorperazine Maleate as Reagent

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