10274. o-Cresolphthalein Complexone

Nomenclature

CAS number: 2411-89-4
N,N′-[(3-Oxo-1(3H)-isobenzofuranylidene)bis[(6-hydroxy-5-methyl-3,1-phenylene)methylene]]bis[N-(carboxymethyl)glycine]; o-cresolphthalein complexon; o-cresolphthalexone; 3,3′-dimethyl-5,5′-[(N,N-bis(carboxymethyl)amino)methyl]phenolphthalein complexon; metalphthalein; phthalein complexone; phthalein purple.
C32H32N2O12; mol wt 636.60.
C 60.37%, H 5.07%, N 4.40%, O 30.16%.

Description and references

Cation chelating dye; forms 1:1 and 2:1 complexes with metal ions. Prepn from o-cresolphthalein, q.v.: G. Anderegg et al., Helv. Chim. Acta 37, 113 (1954) DOI; J. Krbl, R. Pribil, Chem. Ind. (London) 1957, 233. Spectrophotometric ionization studies: F. Gaizer et al., Talanta 28, 127 (1981) DOI; S. M. Abu-El-Wafa et al., Pak. J. Sci. Ind. Res. 28, 238 (1985). Polarography studies: X. Gao, M. Zhang, Anal. Chem. 56, 1912 (1984) DOI. Metal chelate studies: H. P. Srivastava, D. Tiwari, J. Chem. Eng. Data 41, 821 (1996) DOI; S. M. Abu-El-Wafa et al., J. Coord. Chem. 57, 813 (2004) DOI; T. M. Ismail et al., ibid. 1179 DOI; R. M. Issa et al., Synth. React. Inorg. Met.-Org. Chem. 34, 1087 (2005) DOI; K. Y. El-Baradie et al., Monatsh. Chem. 136, 1157 (2005) DOI. Determn of calcium in biological samples: G. Kessler, M. Wolfman, Clin. Chem. 10, 686 (1964) PubMed; B. C. Ray Sarkar, U. P. S. Chauhan, Anal. Biochem. 20, 155 (1967) DOI PubMed; K. Lorentz, Clin. Chim. Acta 126, 327 (1982) DOI PubMed; C. M. Corns, C. J. Ludman, Ann. Clin. Biochem. 24, 345 (1987) PubMed.

Chemical structure

Properties

Solid from ethanol, mp 186° (as monohydrate). Irritant. pKa1 3.95; pKa2 6.85; pKa3 7.64; pKa4 8.50; pKa5 9.10; pKa6 10.30. Absorption max (0.1 M NH3-NH4Cl, pH 9): 580 nm (ε 820). Aq solns colorless at pH < 8; red at pH ≥ 8. Slightly sol in water, ethanol.

Use

Chromogenic indicator for complexometric and spectrophotometric determn of metal ions. In chelation ion chromatography. In determn of calcium in biological samples.