A triazole derivative as a new acid-base indicator

  • Volkan Numan Bulut Macka Vocational School, Karadeniz Technical University, 61750 Macka, Trabzon, Turkey
  • Celal Duran Department of Chemistry, Faculty of Arts and Sciences, Karadeniz Technical University, 61080 Trabzon, Turkey
  • Ali Gundogdu Department of Chemistry, Faculty of Arts and Sciences, Karadeniz Technical University, 61080 Trabzon, Turkey
  • Mustafa Soylak Department of Chemistry, Faculty of Science, Erciyes University, 38039 Kayseri, Turkey
  • Nuri Yildirim Department of Chemistry, Faculty of Arts and Sciences, Karadeniz Technical University, 61080 Trabzon, Turkey
  • Mehmet Tufekci Department of Chemistry, Faculty of Arts and Sciences, Karadeniz Technical University, 61080 Trabzon, Turkey
Keywords: Acid-base indicator, 3-Benzyl-4-p-nitrobenzylidenamino-4, 5-dihydro-1, 2, 4-triazole-5-on, UV-Vis spectrometry, Resonance, Transition point, Titrimetry

Abstract

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 103 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.

 

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

 

 

Bull. Chem. Soc. Ethiop. 2010, 24(3), 457-460.
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Articles

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eISSN: 1726-801X
print ISSN: 1011-3924