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Analytical uses of charge transfer complexes—Determination of piperidines
MICROCHEMICAL
JOURNAL
31, 210-213 (1985)
Analytical
Uses of Charge Transfer ComplexesDetermination of Piperidines
U. MUFULIKRISHNA*ANDMANNAMKRISHNAMURTHY~ *Department
of Chemistry, TDepartment
P.G. Extension Centre, Andhra University, Nuzvid 521 201, India, and of Chemistry, Andhra University, Waltair 530 003, India
Received November 14, 1982 A simple spectrophotometric determination of piperidine and some methyl-substituted piperidines has been proposed. The method is based on the blue-colored charge transfer complex formation of the nitrogen bases with tetrachloro-1,2-benzoquinone in chloroform. The method is rapid and sensitive to 5.5 kg ml-’ piperidine and has the applicability for the assay of piperidine hydrochloride. 6 198s Academic PFX, hc.
INTRODUCTION
Piperidine is familiar in the field of chemistry and biological process. Fluorosulfuric acid (II) and hydrochloric acid (26, 17) are the reported reagents for the titrimetric analysis of piperidine. Photometry (6, 23) and potentiometry (5, 12) are also cited for the determination. Indirect determinations based on cyanoethylation (10) and atomic absorption (18) and paper chromatography (2) are also reported for the estimation of piperidine. Piperidine is an n-electron donor and will form intensely stable, colored charge transfer complexes with quinones (9). Especially because of the very rapid complex formation, selectivity and sometimes due to their high molar absorptivity the methods involving the formation of charge transfer complexes are usually simple and convenient (25) for the assay of compounds. Based on the complex formation of piperidine with 1,Cbenzoquinone (7) and tetrachloro- 1,4-benzoquinone (8), Muralikrishna and co-workers reported the sensitive detection of piperidine, very recently. Because of the reaction with the parent or tetrachloro-1,4-benzoquinone is known to be slow (1, 3, 7, S), the authors undertook the studies with tetrachloro-1 ,Zbenzoquinone, a much more stronger n-acceptor, with an electron affinity of 1.55 eV on Briegleb’s scale (4) and now they report the spectrophotometric determination of piperidines in chloroform media. MATERIALS
AND METHODS
Tetrachloro-1,2-benzoquinone (Aldrich, Belgium) was recrystalized twice from glacial acetic acid. Piperidine and methyl-substituted piperidines (Fluka, Switzerland) were purified as reported earlier (7). Chloroform was used as solvent. Stock solutions of tetrachloro-1,2-benzoquinone (5 mg ml-‘) and piperidines (1 mg ml-i) were prepared in chloroform. 210 0026-265X/85 $1.50 Copyright 0 1985 by Academic Press, Inc. All rights of reproduction in any form reserved.
DETERMINATION
211
OF PIPERIDINES
TABLE 1 Determination of Piperidines Piperidine substituent
hmaxa
Beer’s law range
Sandell’s sensitivity
(nm)
tw ml-9
(kg cm-*)
Standard deviationb
Parent 4-Methyl 3-Methyl 2-Methyl l-Methyl 3,5-Dimethyl 2,6-Dimethyl
590 590 590 592 597 590 594
5-55 6-65 6-65 30-350 20-230 7-75 80-850
0.060 0.072 0.072 0.370 0.240 0.083 0.900
0.0039 0.0043 0.0045 0.0081 0.0060 0.0032 0.0079
a The spectroscopic studies on the electron donor-acceptor interaction will be published elsewhere. b For five determinations.
Procedure
Suitable aliquots of piperidine and 1.0 ml of the reagent in chloroform were mixed in lo-ml volumetric flasks. A blue color was developed and the absorption was measured at the A,,, (Table I), after 5 min, on a CZ spekol ZV spectrophotometer using matched stoppered cells of 1 cm path and using the reagent blank. A calibration curve was drawn and the unknowns were calculated. For 4-methyl, 3-methyl, and 3,Sdimethyl piperidines the same procedure was followed. But for l-methyl, 2-methyl, and 2,6-dimethyl piperidines, 2.0 ml of the reagent was added and the absorption was measured after 10 min. The results are indicated in Table 1. TETRACHLORO 0.6
10
8
- 1.2
- BENZOOUINONE,
6 I
PIPERIDINE.
4
ml 2
0
0.6
ml.
FIG. 1. Job’s method of continuous variation for piperidine and tetrachloro-1,2-benzoquinone. at the initial concentrations 6.9 x iOm4M (B) and 3.8 X 10e4 M (A).
212
MURALIKRISHNA
AND KRISHNAMURTHY
o’6K 0.5
t
$7+-----=-~::9 0.1 0.2
FIG. 2. Stability of the complex between piperidine (2.5 x 10m4M) and tetrachloro-1,2-benzoquinone (2.5 X 1O-3 M).
RESULTS AND DISCUSSION
The stoichiometry between tetrachloro-1,2-benzoquinone and piperidine is found to be 1:2, by the Job’s method of continuous variation (Fig. 1). Further, Fig. 1 also indicates that in presence of excess of the reagent the absorbance of the complex obeys Beer’s law. The complex is reasonably stable (Fig. 2) and reproducible absorbances are measured even after 12 hr. The substituent effect on piperidine is almost identical, in case of 4-methyl, 3methyl, and 3,Sdimethyl piperidines, and the sensitivity is also similar. However, the comparatively high values of the Sandell’s sensitivity (Table 1) in case of lmethyl, 2-methyl, and 2,6-dimethyl piperidines may be due to the steric hindrance offered by the substituents to the donation site (7, 14). The proposed method for the determination of piperidine is comparable with the accepted methods (6, 12). The present method is more simple, direct, rapid, sensitive, convenient, and advantageous than the earlier reported methods (2-6, 10-13, 16-18). Piperazine, a similar nitrogen base having two donation sites, will interfere in all concentrations. But pyridine and pyrazine up to fivefold excess to that of piperidine do not interfere. TABLE 2 Assay of Piperidine Hydrochloride Amount taken (w ml-‘)
Amount found” (w ml-‘)
Recovery“ m
8.0 16.0 32.0 64.0 72.0
1.9 16.0 32.1 63.5 71.6
98.8 100.0 100.3 99.3 99.5
4 Average of five determinations.
DETERMINATION
Determination
of piperidine
OF PIPERIDINES
213
hydrochloride
Piperidine hydrochloride (equivalent to 25-50 mg of piperidine was dissolved in 25 ml water and then was treated with 10 ml of 10% aqueous sodium hydroxide. The piperidine was extracted into chloroform (3 times each with 30 ml) and the extractants were made up to 100 ml. The procedure for the determination of piperidine was followed and the unknowns were read from the standard calibration graph. Very good results (Table 2) were obtained. ACKNOWLEDGMENT One of the authors, M. Krishnamurthy, thanks the CSIR, New Delhi, for the award of research fellowship.
REFERENCES 1. Al-Ghabsha, T. S., Rahim, S. A., and Townshend, A., Spectrophotometric determination of microgram amounts of amine with chloranil. Anal. Chim. Acfa 85, 189-194 (1976).
2. Bannard, R. A. B., and Casselman, A. A., Paper chromatography of some amine hydrochlorides and acetates in acidic solvent systems, Canad. J. Chem. 43, 395-404 (1965). 3. Bela1 Saied, Elsayed M, A. Hady, Abdel-Hamid, Mohammad E., and Abdine, H., Utility of chloranil in assay of naphazoline, clemizole, penicillin G sodium and piperazine. .I. Pharm. Sci. 70, 127-130 (1981). 4. Briegleb, G., Electron affinity of organic molecules. Angew. Chem. Znt. Ed. 3, 617-632 (1964). 5. Hassan, S. S. M., Tadros, F., and Selig, W., Microdetermination and pKa measurement of some aliphatic amines using the copper-ion-selective electrode. Microchem. J. 26, 426-435 (1981). 6. Hosni, K., and Manfred, R., Photometric determination of amines with 5-isothiocyanato-1,3dioxo-2-p-tolyl-2,3-dihydro-lH-benzo[de]isoquinoline. Z. Anal. Chem. 294, 286 (1979). 7. Muralikrishna, U., and Krishnamurthy, M., Molecular interaction between p-benzoquinone and piperidines. Indian J. Chem., Sect. A. 21, 1018 (1982). 8. Muralikrishna, U., and Rao, N. S., Detection and determination of piperidine and piperazine using chloranil as a reagent. Zndinn J. Chem. Sect. A. 16, 993 (1978). 9. Muralikrishna, U., Seshasayi, Y. V. S. K., and Krishnamurthy, M., Studies on charge transfer complexes with alicyclic n-donors, J. Zndian Chem. Sot., 60, 447 (1983). 10. Obtemperanskaya, S. I., and Khoe, N. D., Determination of primary or secondary amino groups by cyanoethylation. Vest Mosk. Univ., Ser. 2:Khim. 116-117 (1969); Anal. Abstr. 19, 3972 (1970). 11. Paul, R. C., and Pahil, S. S., Fluorosulphuric acid as a titrant in alcoholic solvents. Anal. Chim. Acra 30, 466-472 (1964). 12. Petrov, S. I., Buchneva, L. M., and Kazitsyna, L. A., Diazometrid titration of bases in nonaqueous media with potentiometric end point detection. Zh. Anal. Khim. 34, 367-373 (1979). 13. Rawat, J. P., and Bhattachajee, P., Spectrophotometric determination of amines by copper (II). Indian J. Chem. Sect. A 14, 544 (1976). 14. Seshasayi, Y. V. S. K., Spectroscopic and kinetic studies on the formation and transformation of some charge transfer complexes. Ph.D., thesis, pp. 59-61. Andhra University, Waltair, 1981. 15. Townshend, A., Analytical applications of molecular complexes. Proc. Sot. Anal. Chem. 10, 3941 (1973). 16. Wiese, G., and Thiele, B., Titrations with dilatometric indication. XIII. Dilatometry as a rapid analytical method in organic solvents. 2. Anal. Chem. 289, 272-274 (1978). 17. Yao-Zu, C., and Dian-Qun, H., Micro titration of organic weak bases in concentrated salt solution. Lau-Chou Tu Hsueh Hsueh Pao, Tzu Jan K’o Hsueh Pan 74-79 (1981); Chem. Abstr. 95, 196869~(1981). 18. Yukio, M., Toshiyuki, M., and Yoshikazu, E, Indirect determination of aliphatic amines by atomic absorption spectrophotometry. Bunseki Kugaku 30, 475-477 (1981).
JOURNAL
31, 210-213 (1985)
Analytical
Uses of Charge Transfer ComplexesDetermination of Piperidines
U. MUFULIKRISHNA*ANDMANNAMKRISHNAMURTHY~ *Department
of Chemistry, TDepartment
P.G. Extension Centre, Andhra University, Nuzvid 521 201, India, and of Chemistry, Andhra University, Waltair 530 003, India
Received November 14, 1982 A simple spectrophotometric determination of piperidine and some methyl-substituted piperidines has been proposed. The method is based on the blue-colored charge transfer complex formation of the nitrogen bases with tetrachloro-1,2-benzoquinone in chloroform. The method is rapid and sensitive to 5.5 kg ml-’ piperidine and has the applicability for the assay of piperidine hydrochloride. 6 198s Academic PFX, hc.
INTRODUCTION
Piperidine is familiar in the field of chemistry and biological process. Fluorosulfuric acid (II) and hydrochloric acid (26, 17) are the reported reagents for the titrimetric analysis of piperidine. Photometry (6, 23) and potentiometry (5, 12) are also cited for the determination. Indirect determinations based on cyanoethylation (10) and atomic absorption (18) and paper chromatography (2) are also reported for the estimation of piperidine. Piperidine is an n-electron donor and will form intensely stable, colored charge transfer complexes with quinones (9). Especially because of the very rapid complex formation, selectivity and sometimes due to their high molar absorptivity the methods involving the formation of charge transfer complexes are usually simple and convenient (25) for the assay of compounds. Based on the complex formation of piperidine with 1,Cbenzoquinone (7) and tetrachloro- 1,4-benzoquinone (8), Muralikrishna and co-workers reported the sensitive detection of piperidine, very recently. Because of the reaction with the parent or tetrachloro-1,4-benzoquinone is known to be slow (1, 3, 7, S), the authors undertook the studies with tetrachloro-1 ,Zbenzoquinone, a much more stronger n-acceptor, with an electron affinity of 1.55 eV on Briegleb’s scale (4) and now they report the spectrophotometric determination of piperidines in chloroform media. MATERIALS
AND METHODS
Tetrachloro-1,2-benzoquinone (Aldrich, Belgium) was recrystalized twice from glacial acetic acid. Piperidine and methyl-substituted piperidines (Fluka, Switzerland) were purified as reported earlier (7). Chloroform was used as solvent. Stock solutions of tetrachloro-1,2-benzoquinone (5 mg ml-‘) and piperidines (1 mg ml-i) were prepared in chloroform. 210 0026-265X/85 $1.50 Copyright 0 1985 by Academic Press, Inc. All rights of reproduction in any form reserved.
DETERMINATION
211
OF PIPERIDINES
TABLE 1 Determination of Piperidines Piperidine substituent
hmaxa
Beer’s law range
Sandell’s sensitivity
(nm)
tw ml-9
(kg cm-*)
Standard deviationb
Parent 4-Methyl 3-Methyl 2-Methyl l-Methyl 3,5-Dimethyl 2,6-Dimethyl
590 590 590 592 597 590 594
5-55 6-65 6-65 30-350 20-230 7-75 80-850
0.060 0.072 0.072 0.370 0.240 0.083 0.900
0.0039 0.0043 0.0045 0.0081 0.0060 0.0032 0.0079
a The spectroscopic studies on the electron donor-acceptor interaction will be published elsewhere. b For five determinations.
Procedure
Suitable aliquots of piperidine and 1.0 ml of the reagent in chloroform were mixed in lo-ml volumetric flasks. A blue color was developed and the absorption was measured at the A,,, (Table I), after 5 min, on a CZ spekol ZV spectrophotometer using matched stoppered cells of 1 cm path and using the reagent blank. A calibration curve was drawn and the unknowns were calculated. For 4-methyl, 3-methyl, and 3,Sdimethyl piperidines the same procedure was followed. But for l-methyl, 2-methyl, and 2,6-dimethyl piperidines, 2.0 ml of the reagent was added and the absorption was measured after 10 min. The results are indicated in Table 1. TETRACHLORO 0.6
10
8
- 1.2
- BENZOOUINONE,
6 I
PIPERIDINE.
4
ml 2
0
0.6
ml.
FIG. 1. Job’s method of continuous variation for piperidine and tetrachloro-1,2-benzoquinone. at the initial concentrations 6.9 x iOm4M (B) and 3.8 X 10e4 M (A).
212
MURALIKRISHNA
AND KRISHNAMURTHY
o’6K 0.5
t
$7+-----=-~::9 0.1 0.2
FIG. 2. Stability of the complex between piperidine (2.5 x 10m4M) and tetrachloro-1,2-benzoquinone (2.5 X 1O-3 M).
RESULTS AND DISCUSSION
The stoichiometry between tetrachloro-1,2-benzoquinone and piperidine is found to be 1:2, by the Job’s method of continuous variation (Fig. 1). Further, Fig. 1 also indicates that in presence of excess of the reagent the absorbance of the complex obeys Beer’s law. The complex is reasonably stable (Fig. 2) and reproducible absorbances are measured even after 12 hr. The substituent effect on piperidine is almost identical, in case of 4-methyl, 3methyl, and 3,Sdimethyl piperidines, and the sensitivity is also similar. However, the comparatively high values of the Sandell’s sensitivity (Table 1) in case of lmethyl, 2-methyl, and 2,6-dimethyl piperidines may be due to the steric hindrance offered by the substituents to the donation site (7, 14). The proposed method for the determination of piperidine is comparable with the accepted methods (6, 12). The present method is more simple, direct, rapid, sensitive, convenient, and advantageous than the earlier reported methods (2-6, 10-13, 16-18). Piperazine, a similar nitrogen base having two donation sites, will interfere in all concentrations. But pyridine and pyrazine up to fivefold excess to that of piperidine do not interfere. TABLE 2 Assay of Piperidine Hydrochloride Amount taken (w ml-‘)
Amount found” (w ml-‘)
Recovery“ m
8.0 16.0 32.0 64.0 72.0
1.9 16.0 32.1 63.5 71.6
98.8 100.0 100.3 99.3 99.5
4 Average of five determinations.
DETERMINATION
Determination
of piperidine
OF PIPERIDINES
213
hydrochloride
Piperidine hydrochloride (equivalent to 25-50 mg of piperidine was dissolved in 25 ml water and then was treated with 10 ml of 10% aqueous sodium hydroxide. The piperidine was extracted into chloroform (3 times each with 30 ml) and the extractants were made up to 100 ml. The procedure for the determination of piperidine was followed and the unknowns were read from the standard calibration graph. Very good results (Table 2) were obtained. ACKNOWLEDGMENT One of the authors, M. Krishnamurthy, thanks the CSIR, New Delhi, for the award of research fellowship.
REFERENCES 1. Al-Ghabsha, T. S., Rahim, S. A., and Townshend, A., Spectrophotometric determination of microgram amounts of amine with chloranil. Anal. Chim. Acfa 85, 189-194 (1976).
2. Bannard, R. A. B., and Casselman, A. A., Paper chromatography of some amine hydrochlorides and acetates in acidic solvent systems, Canad. J. Chem. 43, 395-404 (1965). 3. Bela1 Saied, Elsayed M, A. Hady, Abdel-Hamid, Mohammad E., and Abdine, H., Utility of chloranil in assay of naphazoline, clemizole, penicillin G sodium and piperazine. .I. Pharm. Sci. 70, 127-130 (1981). 4. Briegleb, G., Electron affinity of organic molecules. Angew. Chem. Znt. Ed. 3, 617-632 (1964). 5. Hassan, S. S. M., Tadros, F., and Selig, W., Microdetermination and pKa measurement of some aliphatic amines using the copper-ion-selective electrode. Microchem. J. 26, 426-435 (1981). 6. Hosni, K., and Manfred, R., Photometric determination of amines with 5-isothiocyanato-1,3dioxo-2-p-tolyl-2,3-dihydro-lH-benzo[de]isoquinoline. Z. Anal. Chem. 294, 286 (1979). 7. Muralikrishna, U., and Krishnamurthy, M., Molecular interaction between p-benzoquinone and piperidines. Indian J. Chem., Sect. A. 21, 1018 (1982). 8. Muralikrishna, U., and Rao, N. S., Detection and determination of piperidine and piperazine using chloranil as a reagent. Zndinn J. Chem. Sect. A. 16, 993 (1978). 9. Muralikrishna, U., Seshasayi, Y. V. S. K., and Krishnamurthy, M., Studies on charge transfer complexes with alicyclic n-donors, J. Zndian Chem. Sot., 60, 447 (1983). 10. Obtemperanskaya, S. I., and Khoe, N. D., Determination of primary or secondary amino groups by cyanoethylation. Vest Mosk. Univ., Ser. 2:Khim. 116-117 (1969); Anal. Abstr. 19, 3972 (1970). 11. Paul, R. C., and Pahil, S. S., Fluorosulphuric acid as a titrant in alcoholic solvents. Anal. Chim. Acra 30, 466-472 (1964). 12. Petrov, S. I., Buchneva, L. M., and Kazitsyna, L. A., Diazometrid titration of bases in nonaqueous media with potentiometric end point detection. Zh. Anal. Khim. 34, 367-373 (1979). 13. Rawat, J. P., and Bhattachajee, P., Spectrophotometric determination of amines by copper (II). Indian J. Chem. Sect. A 14, 544 (1976). 14. Seshasayi, Y. V. S. K., Spectroscopic and kinetic studies on the formation and transformation of some charge transfer complexes. Ph.D., thesis, pp. 59-61. Andhra University, Waltair, 1981. 15. Townshend, A., Analytical applications of molecular complexes. Proc. Sot. Anal. Chem. 10, 3941 (1973). 16. Wiese, G., and Thiele, B., Titrations with dilatometric indication. XIII. Dilatometry as a rapid analytical method in organic solvents. 2. Anal. Chem. 289, 272-274 (1978). 17. Yao-Zu, C., and Dian-Qun, H., Micro titration of organic weak bases in concentrated salt solution. Lau-Chou Tu Hsueh Hsueh Pao, Tzu Jan K’o Hsueh Pan 74-79 (1981); Chem. Abstr. 95, 196869~(1981). 18. Yukio, M., Toshiyuki, M., and Yoshikazu, E, Indirect determination of aliphatic amines by atomic absorption spectrophotometry. Bunseki Kugaku 30, 475-477 (1981).