Synthesis of non-substituted phthalocyanines by standard and non-standard techniques. Influence of solvent nature in phthalocyanine preparation at low temperature by UV-treatment of the reaction system

Several synthetic techniques for metal-free phthalocyanines (Pc) and d- and f-metal phthalocyaninates (“PcM”) starting from different precursors (phthalonitrile, urea and phthalic anhydride, phthalimide, phthalic acid, etc.) are reviewed. Conventional methods are presented, as well as some less well-known techniques such as those using ultrasound, laser, microwaves, or nuclear transformation. Special attention is paid to phthalocyanine formation at relatively low temperatures (0–60 °C). Experimental results on Pc formation using UV-irradiation of the reaction system are presented.