Synthesis of Historical Azo Pigments: The Challenge and Opportunity of the Nearly Forgotten

ABSTRACTSynthetic organic pigments (SOPS) find wide use in modern and contemporary works of art. These laboratory-made pigments are used in many fields, including industrial and architectural paints, printing inks, plastics, textiles, and artists’ materials. They have been examined by a variety of techniques including spectroscopic methods such as Fourier transform infrared spectroscopy (FTIR), Raman, and X-ray powder diffraction (XRD) as well as chromatographic or mass spectrometric techniques such as pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and laser desorption ionization mass spectrometry (LDI-MS). Often, a combination of techniques has been used to examine these pigments. Previously, we used a combination of Raman spectroscopy and LDI-MS to characterize commercially available SOPS. However, many pigments, termed “historical” are no longer manufactured, and therefore, may not have been characterized. This paper describes the synthesis of members of several classes of SOPS and their characterization.