Kozo. Momoki

Chelate formation of zirconium with xylenol orange and semi-xylenol orange

Abstract The composition, formation constants, and molar absorptivities of the chelates of zirconium ion wtih xylenol orange and semi-xylenol orange are investigated spectrophotometrically in strong acid medium at ionic strength 3.0 (NaClO4 and HClO4). The data obtained were processed with a newly-constructed computer program and with LETAGROP/SPEFO. In the zirconium—xylenol orange system, Zr · H3 L, Zr· H4L, and Zr2 · L are present with logarithmic overall formation constants of 37.80, 38.68, 43.47, and molar absorptivities of 3.10 × 104 (485 nm), 5.98 × 104 (528 nm), 9.50 × 104 (551 nm) I mol-1 cm-1, respectively. The chelates Zr · L and Zr · HL were found in the zirconium—semi-xylenol orange system with logarithmic overall formation constants of 26.25 and 27.56, and molar absorptivities of 5.70 × 104 (532 nm) and 8.30 × 104 (535 nm) 1 mol-1 cm-1, respectively. Semi-xylenol orange is more sensitive and reliable than xylenol orange as a spectrophotometric reagent for zirconium.