N-hydroxy-N,N′-diphenylcinnamamidine (HDPCA) as a new reagent for extractive separation and photometric determination of vanadium(V)

SHORT COMMUNICATIONS

698

REFERENCES 1. H. Malissa and F. Schoffmann, ~i~~e~j~. Acta, 1955, 187. 2. L. Rocks and H. Malissa, /Inal. Chim. Acta, 1964, 30, 106. 3. I. M. Gibalo, I. P. Alimarin and P. Davvadorzh. Vestn. Mosk. Univ.. Ser. II, Khim., 1965, u), 73. 4. C. E. Mulford, At. Ahs. ~ews~~rrer. 1966, 5, 88. 5. J. W. Husler, ibid., 1970, 9, 31. 6. M. B. Kalt and D. F. Bohz, Anal. Chem., 1968, 40,1068. 7. A. Traub and D. F. Boltz, Mikrochim. Acta, 1969, 749. and D. F. Boltz, Anal. Lett.. 1969, 8. R. W. Looyenga 2, 491. 9. P. G. Brewer, D. W. Spencer and G. L. Smith. ilSTM Spec. Tech. Pub!., 1969, No. 443, 70. 10. W. Likussar, G. Sparks and D. F. Boltz, Anal. Chim. Acta, 1970, 52, 349. 11. W. Likussar, C. Sagan and D. F. Boltz, Mikrochim. Acta. 1970, 683. and S. Ito, Bun12. K. Hayashi, Y. Sasaki, M. Nakanishi srki K~~ku, 1971, 19, 1673. 13. K. Hayashi and K. Ito. ibid.. 1971, 20. 1550. 14. H. K. Y. Lau, H. A. Droll and P. F. Lott, Anat. Chim. Acta, 1971. 56, 7. 15. W. Likussar and D. F. Boltz. Anal. Chem.. 1971, 43, 1213. and D. F. Boltz. ~ik~ue~i~~. Acta, 16. R. W. Looyenga 1971, 507. 17. K. Hayashi, Y. Sasaki and K. Ito, Bunsrki ic;agaku, 1972, il, 1338. and D. F. Boltz, T~~lanfa. 1972, 19, 18. R. W. Looyenga 82. 19. H. Okusa, Y. Ueda, K. Ota and K. Kawano, Btcnseki Kagaku, 1973, 22, 84. 20. H. Sakurai, ibid., 1975. 24, 52. Tulanta, 1977, 24, 330. 21. T. Kamada and Y. Yamamoto, G. H. Sparks and D. F. Boltz, Anal. 22. W. Lukussar, Chim. Acta. 1970. 52, 349. 23. A. S. Berger. W. Likussar and D. F. Boltz. Microchem. J.. 1971, 16. 286. T. Murata and S. Ueda, Bunseki 24. Y. Yamamoto, Kquku, 1976, 25, 851.

25. W. Westwood and A. Mayer, Analyst. 1947, 72, 464. 26. C. H. R. Gentry and L. G. Sherrington, ibid., 1948, 73, 57. Anal. Chem., 1949, 21, 1098. 27. I. Geld and J. Carroll, ibid., 28. H. Freund, M. L. Wright and R. K. Brookshier, 1951, 23, 781. and C. E. Johnson, ibid., 1954, 26, 29. C. E. Crouthamel 1284. iv. H. Nishida, Buns~ki Osaka. 1955. 4, 523. 31. B. McDuffie, W. R. Bandi and L. M. Melnick, Anal. Chrm.. 1959, 31, 1311. 32, E. B. Sandell, Colorimerric Determination of Traces oj Metals, 3rd Ed., p. 886. Wiley, New York, 1959. 33. C. L. Luke, Anal. Chem., 1964. 36, 1327. 34. A. G. Fogg, D. R. Marriott and D. T. Burns, Analyst, 1970, 9.5, 848. 35. C. C. Miller. ibid.. 1944. 69, 109. ibid., 1947, 72, 189. 36. B. Bagshawe and R. .l. Truman, E. W. Hobart and H. K. Oberthin, 37. S. Kallmann, Talanta, 1968, 15. 892. Anal. Chem., 1957, 38. L. E. Bricker and C. R. Waterbury, 29, 1093. 39. K. Motojima and H. Hashitani, Butrsrki Kayaka, 1960, 9. 161. 40. A. R. Eberle, Anal. Chrm., 1963, 35, 669. 41. M. Vrchlabsky and L. Sommer, Talanra, 1968, 15, 887. 42. A. I. Busev and T. A. Sokolova, J. Anal. Chum.. USSR, 1968, 23. 1186. and N. G. Yanklo43. L. I. Lebedeva, Z. G. Golubtsova vich. ibid., 1971, 26, 1754. 44. G. J. Lennard, Analyst, 1949, 74, 253. 45, M. Kiboku and C. Yoshimura. Bunsrki Kngaku, 1958, 7. 488. 46, N. Ishibashi and H. Kohara. ibid.. 1964, 13, 239. ibid., 47. T. Shimizu, K. Kato, S. Oyama and K. Hosohara, 1966, 15, 125. and R. S. Tramm, J. 48. S. B. Savvin, E. G. Namvrina Anal. Chem. USSR, 1972. 27, 87. and S. P. Bag, Anal. Chim. Acra, 49. A. K. Chakrabarti 1972. 59, 225. ~unseki Kagaku. 1973, 22, 50. Y. Shijo and T. Takeuchi, 51 1. Mori, ibid.. 1974, 23, 291.

N-HYDROXY-NJ’-DIPHENYLCINNAMAMIDINE (HDPCA) AS A NEW REAGENT FOR EXTRACTIVE SEPARATION AND PHOTOMETRIC DETERMINATION OF VANADIUM KANAK

KANTI

Department

DEB and

RAJENDRA

of Chemistry, Ravishankar Raipur-492002, India

K. MISHRA University,

(Receiwd 7 September 1977. Recised 11 May 1978. Accepted 2 June 1978) Summary-N-Hydroxy-N,N’-diphenylcinnamamidine (HDPCA) forms a blue-violet coloured I:2 complex (metal:ligand) with vanadium(V), which can be quantitatively extracted into chloroform from l.O-9.5M acetic acid medium. Based on this colour reaction, a sensitive and highly selective method for the spectrophotometric determination of microgram quantities of vanadium(V) has been developed. The complex shows maximum absorption at 570nm and obeys Beer’s law in the vanadium concentration range 0.6-12.5 pg/ml. The method has been applied to alloy steels. The reagents and methods employed metric determination of vanadium reviewed by Svehfa and T61g.i

for the spectrophotohave been recently

N-Benzoylphenylhydroxylamine (BPHA) logues2-6 have enjoyed a vogue as reagents but have recently been criticised.‘-“’

and its anafor vanadium,

SHORT

In the light of this and in continuation of our studies on the chemistry of hydroxyamidines,“-‘4 it was thought worthwhile to synthesize and investigate N-hydroxy-N,N’diphenylcinnamamidine (HDPCA), I, which possesses a new type of functional grouping, -N=C-N(OH)-, in which a basic azomethine nitrogen atom provides the co-ordination site. It can be prepared from common laboratory chemicals, and gives a water-insoluble blue-violet vanadium(V) complex in l&9.5,%4 acetic acid medium. This complex is quantitatively extractable into chloroform, and on this basis, a simple, rapid and highly selective spectrophotometric method for the determination of trace quantities of vanadium has been developed. Large amounts of almost all common ions, including iron, molybdenum, manganese, chromium and rare earths do not interfere. In concentrated acetic acid medium vanadium(V) is not reduced and hence the extraction is quantitative. Moreover, Ag, Pb, Hg and Tl form no precipitate in acetic acid medium and therefore their prior separation is not necessary. The presence of traces of alcohol, added as stabilizer in chloroform, affects neither the position of the absorption band nor the stability and absorbance of the complex. The sensitivity of the HDPCA method is comparable with that of the BPHA method. The method is reproducible and applicable to the determination of vanadium in alloy steels. EXPERIMENTAL

Reagents N-Hpdroxy-N,N’-diphen!/cinnamamidine. An ethereal solution of N-phenylcinnamimidoyl chloride, prepared by the action of thionyl chloride on cinnamanilide in toluene, following the method of Sonn and Muher” was added to an equimolar ethereal solution of N-phenylhydroxylamine over a period of 30 min. The temperature was maintained at O-5 throughout. A light brown oil separated in the initial stages of the reaction. Shaking and scratching of the oil was continued for 2 hr and then the solvent was removed by distillation. Ammonia solution (5A4, 40 ml) was added to the oil and triturated for 5 min. The resulting solid was washed with water and recrystallized from 60”/, ethanol to yield shining yellow crystals, m.p. 138-9’; yield 50%. Found: C, 80.5’?,,; H, 6.07:;: N. 8.5:“: &HL8NZ0 requires C, 80.27”;,; H. 5.73”;: N, 8.91%. The infrared specTable

Species

added

FCll BrNO,

so:-

PO? AsG: B,O; Thiourea Triethanolamine Citrate Tartrate

Ag+ Ca”. BaZf or Sr*+ Be2+ or MgZt Pb’+ Zn’+ Cd’+ Hg’ + Sb’+ Bi3+ Al3+

1. Tolerance

limits for diverse

Tolerance limit, ppm 1000 7000 3000 5600 5000 1000 500 700 800 400 1000 800 1400 2400 1600 1500 1640 1600 1200 1280 800 1000

699

COMMUNICATIONS

trum recorded for the mull in nujol and hexaclorobutadiene) gave bands at 3120 cm-’ (strong intramolecular hydrogen bonding), 3050 cm- ’ (aromatic CH stretch.), 1595cm-’ (C=N stretch), 1575cm-’ (C=C aromatic) and 935cm-’ (N-O). The ultraviolet spectrum (950/, ethanol solution) gave maxima at: 213 nm (log E, 4.322) 293 nm (log E 4.260) and 357 nm (log E, 4.076). A 0.1% solution of the reagent in analytical reagent grade chloroform was used for extraction purposes, Standard vanadium(V) stock solution. Prepared by dissolving 1.141 g of ammonium metavanadate in 1 litre of doubly distilled water and standardized titrimetrically.‘h Recommended

procedure

To 10 ml of solution containing up to 100 pg of vanadium(V), in a separatory funnel, add 10 ml of glacial acetic acid and dilute to 25ml with distilled water. Add 6 ml of 0.1% reagent solution, shake vigorously for about 1 min and allow the phases to separate. Run the lower (organic) phase into a 50-ml beaker containing 2 g of anhydrous sodium sulphate. Wash the aqueous phase with two 5-ml portions of chloroform and add the washings to the beaker. After 30 set decant the combined extracts into a 25-ml standard flask. Wash the sodium sulphate with chloroform, adding the washings to the main solution and dilute to volume. Measure the absorbance at 570 nm against a reagent blank. As the reagent has practically no absorbance at wavelengths > 500 nm, chloroform can also be used as reference solution. Deduce the amount of vanadium in the sample solution from a calibration curve. RESULTS

A&D DISCLISSIOTY

The absorption spectra of the vanadium complex and the reagent are shown in Fig. 1. The complex shows maximum absorption at 570 nm, where the reagent has no significant absorption. The spectrum is unchanged if the acetic acid concentration used in the extraction lies between 1.0 and 9.5M. Inorganic acids such as sulphuric and hydrochloric are not suitable, as quantitative extraction of vanadium could not be accomplished even after shaking for 2 hr. A number of organic solvents, including benzene. toluene, chloroform, o-dichlorobenzene, chlorobenzene and carbon tetrachloride. extract the complex quantitatively. ions (V 4 ppm:

acetic acid 7M) Tolerance

Species added

ppm

Fe3 + Cr3+ Tl’+ In3+ Ga3’

1000 800 1000 840 800 1000 880 900 1000 60 1500 800 1000 30 60 80 60 2000 800 150 120

CuZ’ Ni*+

coz+ Mn” Pd’+ Th4 + Ce(IV) Se(IV) Ti4 + Zr4+ Nb(V) Ta(V) La3+ or Gd3’

uo:+

Mo(VI) Mn(VI1)

limit.

SHORT COMMIJNlCATlONS

700

Procedure for steel

=. @ Wave&n

B 8%.

I

600

550

4.20

no7

Fig. 1. Absorption spectra of vanadium(V) (4 ppm)-HDPCA complex (--O-O-O--O-) and HDPCA (0.003M: -O-O-O-_) in chloroform. Chloroform was preferred because of the solubility of the reagent and complex in it and the good sensitivity. The colour development is instantaneous and the extraction complete within a minute. The extracted chelate is stable in chloroform for at least 5 days in the temperature range 2&40”. Job’s plot and the mole ratio method” both indicate a I:2 metal to ligand ratio. For maximal colour development the reagent:metal ratio must exceed 6:l. Hence, a 1O:l molar ratio is used for safety, up to a 3O:l molar ratio has no effect on the absorbance. The order of addition of reagents is not critical. The system obeys Beer’s law over the vanadium concentration range of 0.6- 12.5 pgjml. A Ringbom plotr8 indicates that the optimum concentration range is [email protected]. The relative error per I”/, absolute photometric error” is 2.74,. The molar absorptivity is 4.08 x IO3 l.mole-‘.cm-‘. Twenty independent determinations on solutions each containing LOO jq of vanadium gave a mean absorbance of 0.320 and a standard deviation of 0.002. lnfiurnce

of dicerse ions

of cunudium

in BCS steels

Three BCS steels were anaiysed (Table 2).

accurately

and precisely

Table 2. Determination

Vanadium BCS* sample 64a

241/l

252

* Obtained England.

Aclinowledyemenrs--Thanks are due to Professor S. G. Tandon, Head. Department of Chemistry. Ravishankar University, Raipur, for providing research facilities and to C.S.I.R., New Delhi, for awarding a fellowship to one of us (K.K.D.) REFERENCES 1. 2. 3. 4. 5. 6. 7. 8. 9.

The toierance limits for various ions are recorded in Table 1. Thiocyanate changes the colour of the complex to green and shifts E.,,, to 600 nm with an increase in the absorbance, and thus seriously interferes. W(VI) inhibits colour development and all attempts to mask it with common masking agents fail. Mo(VI) reacts with the reagent throughout the acidity range to give a chloroformextractable yellow complex. However. the colour of the extract has no significant absorption at 570 nm and thus does not interfere. Vanadium is completely masked by excess of EDTA. Drtrrminution

Dissolve a steel sample, containing approximately 4 mg of vanadium, in 15-20 ml of aqua regia. Evaporate the solution nearty to dryness, on a hot-plate. Add 5 ml of con~ntrat~ hydrochloric acid and again evaporate to small volume. Cool, dilute to 30 ml, filter off silica, carbon and tungstic acid, washing with hot (IM) hydrochloric acid until free from iron. Concentrate the filtrate to 5 ml, dilute to 50 ml and transfer to a 250-ml standard flask. Wash the tungstic acid precipitate, which tends to retain appreciable amounts of vanadium,” with a few ml of hot 1M acetic acid, add the washings to the main solution and dilute to volume. Pipette 10 ml into a separatory funnel, add dilute potassium permanganate solution until a faint pink persists, adjust the acetic acid concentration to 7M and continue with the recommended procedure.

No.

found,

1.56: 1.55: 1.56: 1.55; 1.55 Average value, 1.55 1.54; 1.55; 1.56: 1.54: 1.55 Average value. 1.55 0.452: 0.456: 0.460: 0.452; 0.455 Average vatue, 0.453 of Analysed

12. i3. 14. 15. 16. 17. 18. 19. 20.

of vanadium Vanadium certificate value, 0I II

00

from Bureau

10. Il.

G. Svehla and G. TSlg, Talanta, 1976, 23, 755. S. C. Shome, An&t, 1950, 75, 27. D. E. Ryan, ibid, 1960, 85, 569. U. Priyadarshini and S. G. Tandon. Anal. Chum., 1961, 33, 435. A. K. Majumdar and G. Das, Anal. Chim. Acta, 1966. 36, 454. A. K. Majumdar, N-Benzo~lphenylhgdroxglamine and its Analoyues, Pergamon, Oxford, 1972. A. D. Shendrikar, Talanta, 1969, 16, 51. H. Goto and Y. Kakita, Bunseki Kagaku, 1961, 10, 904; Chem. Abstr., 1962, 56, 12311 i. 0. A. Vita, W. A. Levier and E. Litteral. Anal. Chim. Acta, 1968, 42, 87. E. M. Donaldson, Talanta, 1970, 17, 583. K. Satyanarayana and R. K. Mishra, Indian J. Chem., 1975, 13, 295. ldem, J. Indian Chem. Sot., 1976, 53, 63, 469, 928. K. K. Deb and R. K. Mishra, ibid., 1976, 53, 178. fdem, Curr. Sci. (Zndiu), 1976, 45, 134. A. Sonn and E. Muller, Ber.. 1919, 52, 1927. 6. Chariot and D. Bezier. Quantitatice Znoryanic Analysis, 3rd Ed., Wiley, New York, 1957. A. E. Harvey Jr. and D. L. Manning, J. Am. Chem. Sot., 1950. 72, 4488. A. Ringbom, Z. Anal. Chem., 1939, 115, 332. G. H. Ayres, Anai. Chem.. 1949, 21, 652. S. G. Clarke, Ana!~sr, 1927, 52, 466.

Samples,

in steels

Relative error, “/0

Standard deviation, 0,’0

1.57

-1.1

+0.006

1.57

-1.5

-i_0.008

0.460

- 1.5

2 0.006

Ltd. Newham

Hall, Middlesbrough.

Yorks,