Synthesis of New Azo Compounds and Their Application for a Simple Spectrophotometric Determination of Methyldopa Drug Using Anthranilic Acid and 2-Aminopyrimidine as Reagents

The goal of the current work is to synthesize methyldopa derivatives. Based on these reactions, two easy, speedy, accurate, inexpensive, and sensitive spectrophotometric approaches have been established for determining methyldopa (MED) in both pure and pharmaceutical forms. The proposed azo-coupling method depends on forming an azo compound between methyldopa drug and 2-AMPY or ANTH to produce two compounds of MED-2AMPY and MED-ANTH in the alkaline medium. The characterization of synthesized compounds utilizing UV-Visible and FT-IR spectra. FT-IR spectra of 2AMPY-MED confirm the existence of OH, C-Hor, C-Hal, NH, N=N, C=O, and C=C vibration at 3455, 3059, 2973, 3100, 1476,1692, and 1560 cm-1, and FT-IR spectra of ANTH-MED confirm the existence of OH, C-Hor, NH, C=O and N=N vibration at 3490, 3050, 3100, 1701 and 1462 cm-1, correspondingly. The obtained color of azo compounds is spectrophotometrically measured for the previously mentioned azo compounds at 450 and 455 nm, respectively. Under perfect conditions, the azo compound solutions exhibited molar absorptivities of 1563.0058 and 2091.0285 L.mol-1.cm-1, Sandell's sensitivity of 0.135 and 0.10 µg.cm-1, and Beer-Lambert's law are obeyed over the ranges 6.25- 62.5 mg. L-1 for the two developed procedures, respectively.