Studies on the synthesis of new porphyrins from cardanol and glycerol

Abstract

Porphyrins are very attractive compounds due to their wide application in many areas of new materials as chemical technology, ecology, medicine and, electronics. In the last years, they are also been a focus of attention owing to their implications to many photocatalytic reactions. Cardanol (isolated form cashew nut shell liquid) and glycerol (side product of biodiesel industry) are raw materials of low aggregated value; however, they hold chemical structures with functionalities that can lead to products of high commercial value to Brazilian industry. Aiming to use these chemical materials, our research group has proposed the synthesis of new hybrid molecular structures of porphyrin-cardanol-glycerol, which will be submitted to test of their photocatalytic properties. The synthetic proposal is based on the reaction of 4-hydroxybenzaldehyde (1) and epichloriridine (2) (derived from glycerol), using pyridine in dichloromethane and FeCl3 as a catalyst, under reflux and stirring. This process will provide the mixture of intermediate 3 and 4. These compounds will be attacked by the nucleophile cardanol (5) in sealed tube, using pyridine and dichloromethane at 120 ºC for 80 hours, giving the intermediate 6. After oxidation of the alcohol 6, the corresponding ketone will be achieved. Continuing the synthesis, these intermediates will separately react with pyrrol, giving the wished porphyrins that in turn will be transformed in macromolecules by treatment with Grubbs catalyst, according to methodologies already known in the literature. The previously synthesized compounds 3, 4, 5 and 6 had their structures confirmed by spectroscopy analyses of NMR (1H and 13C).

Keywords

• cardanol
• glycerol
• porphyrin
• photodynamic therapy