A TRIAZOLE DERIVATIVE AS A NEW ACID-BASE INDICATOR

作者：Bulut Volkan Numan; Duran Celal; Gundogdu Ali; Soylak Mustafa^*; Yildirim Nuri; Tufekci Mehmet

来源：Bulletin of the Chemical Society of Ethiopia, 2010, 24(3): 457-460.

• Acid-base indicator
• 3-Benzyl-4-p-nitrobenzylidenamino-4,5-dihydro-1,2,4-triazole-5-on
• UV-Vis spectrometry
• Resonance
• Transition point
• Titrimetry

In this study a new pH indicator, 3-benzyl-4-p-nitrobenzylidenamino-4,5-dihydro-1,2,4-triazole-5-on (BPNBAT), soluble in acetonitrile: water (1: 4), was developed. The estimation of pH is possible either from the position of the absorption maxima or from the absorbance intensity at a constant wavelength. This feature allowed us to determine the basic transition range of the medium because BPNBAT is colorless at pH lower than 8.5 and showed strong yellow-green color with high extinction coefficient in the pH range of 8.5-10.1. pKa, pH at equivalent point and the molar absorptivity (in the aqueous medium at 380 nm) of BPNBAT are determined as 9.3, 8.3 and 8.8 x 10(3) L.mol(-1).cm(-1), respectively. The color change at the transition range can be attributed to the resonance structures of BPNBAT. The triazole compound was compared with thymolphthalein for accuracy test.

• 出版日期2010