Ecofriendly Porphyrin Synthesis by using Water under Microwave Irradiation

Abstract

Water, under microwave irradiation and at a temperature of 473 K, reaches pressures above 16 bar, being capable to act as catalyst, without the use of organic solvents and oxidants, for meso-substituted porphyrin synthesis. Sustainability of the reaction is proved by E Factor=35 and EcoScale value of 50.5, the highest so far obtained for porphyrin synthesis. Methodology's wide versatility is clearly demonstrated by the good yields obtained for both aryl and alkyl substituted porphyrins. These reaction conditions represent a huge development, not only by using very high concentrations, minimizing organic solvent usage, but also by eradicating toxic expensive solvents and oxidants.

Solventless metallation of low melting porphyrins synthesized by the water/microwave method

“…The characterization data is in accordance with the literature 33. Subsequently, 1-bromo-2-ethylhexane (11 mL, 0.0615 mol) was added and the reaction remained at 80ºC over 18 hours.…”

“…Encouraged by the multiple applications of low-melting point porphyrins we extended the scope of our Water/MW method, in which water, under microwave irradiation, acts as solvent/acid catalyst/oxidant in sub-critical conditions, 33 to the synthesis of low melting point meso-alkyl and meso-aryl substituted porphyrins.…”

“…5-(4-hydroxyphenyl)-10,15,20-tri-(4-(2-ethyl-hexyloxy)phenyl)porphyrin (2) was prepared using the Water/MW, 33 Adler-Longo, 34 Gonsalves-Pereira 35 General procedure for Water/MW method: The mixture of pyrrole (9.8 mmol; 0.68 mL), aldehyde (or mixture of aldehydes) (9.8 mmol) and water (0.2 mL) were mixed in a 10 mL microwave vessel. If the aldehyde was a solid, ultrasound was applied to the closed vessel for 10 minutes.…”

Halogenated meso-phenyl Mn(III) porphyrins as highly efficient catalysts for the synthesis of polycarbonates and cyclic carbonates using carbon dioxide and epoxides

“…Halides, quaternary salts and ionic liquids are known to produce preferentially cyclic carbonates, which are the most stable thermodynamic products [9], while metal complexes can catalyze the formation of polymers and/or cyclic carbonate products, depending from the co-catalyst, substrate and reaction conditions [9]. It should be mentioned that most of the metal based complexes, of which tetrapyrrolic macrocycles are privileged compounds for many applications [13,14,15,16,17,18,19,20,21], require the presence of a co-catalyst, acting as nucleophile, whether added to the reaction (binary catalytic systems) [22,23,24,25] or already included in the structure of the complex (bifunctional catalytic systems) [26].…”

Synthesis and characterization of biocompatible bimodal meso-sulfonamide-perfluorophenylporphyrins

“…The synthetic difficulties and scarce availability of natural porphyrinoids [29,33,34], led to the use of meso-substituted tetrapyrrolic macrocycles, easily obtained by sustainable synthetic methods [12,[35][36][37][38], as the main choice for the development of new generations of PDT agents [8,9,39]. 5,10,15,20-Tetrakis(pentafluorophenyl)porphyrin (TPFPP) is an interesting template to functionalize via nucleophilic substitution reactions [40], making use of nucleophiles such as amines, thiols, alcohols and nitrogen heterocycles [41,42], to improve their avidity for bacteria.…”