SINTESIS SENYAWA orto-FENILAZO-2-NAFTOL SEBAGAI INDIKATOR DALAM TITRASI

Abstract

Synthesis of o-fenilazo-2-naphtol used as indicator in titration has been conducted in this research. The
synthesis was carried out by coupling of diazonium chloride salt with 2-naphtol, and aniline. The product was
characterized using spectroscopy techniques (IR, 1HNMR, and MS), while the pKHIn was determined using UV-vis
spectrometer. The application of the product as indicator in titration was compared to methyl-orange.
The synthesis gave a red crystal with 62.51 % yield. Infra red spectra analysis showed the presence of
characteristic functional groups such as–OH, CH-aromatic, C=C, N=N, CN, CO, and a peak indicated substituents at
ortho position. 1HNMR showed three separated peaks. Mass spectra gave molecular ion peak (M+) at m/z 248. The
red crystal obtained melted at 128-131oC. Based on spectroscopy analysis and melting point, it can be concluded
that the product was o-fenilazo-2-naphtol. The product had a pKHin of 3.16, therefore it can be used as indicator for
acid-base titration which showed equivalent point at pH 5.