SYNTHESIS OF TETRAPHENYLPORPHYRIN AND 5,15-BIS(4-METHYLPHENYL)-10,20-DIPHENYLPORPHYRIN VIA [2+2] CONDENSATION OF 5-PHENYLDIPYRROMETHANE

• Main Author: Indah Putri, Sucilia
• Format: Final Project
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/33698
• Institution: Institut Teknologi Bandung

Porphyrin is macrocycle molecules that exist in nature and have important role in biological processes. Porphyrin and its derivatives have very wide application, such as dye sensitized solar cells, sensor, catalyst, and photodynamic therapy for cancer. Porphyrin and its derivatives can be synthesized through several routes including via condensation of pyrrole with aldehydes and [2+2] condensation of dipyrromethane. In this study, the synthesis of porphyrin derivatives conducted through the [2+2] condensation of dipyrromethane where the formation of tetrapyrrole ring structure by merging two bipyrrole structures. Through this route, syntesis of porphyrin with A.-type or trans A2B2 -type can be done. This study consist of two stages: the synthesis of 5-phenyldipyrromethane, then synthesis tetraphenylporphyrin and 5,15-Bis(4-methylphenyl)-10,20-diphenylporphyrin through [2+2] condensation of 5-phenyldipyrromethane. In the first stage, 5-phenyldipyrromethane was synthesized from pyrrole and benzaldehyde using water as solvent and HCl or TFA as catalyst. Recrystallization process produced white crystals with yield 23% and 15% for HCl and TFA, respectively. The test results show the melting point of crystal are 100-101 oc and 99-100 oc for synthesized with HCl and TFA, respectively. Mass spectrum generated from ESI-MS technique, shows base peak at rn/z 223.12 that refers to peak of [M+Ht. In the second stage, tetraphenylporphyrin was synthesized by the reaction between 5-phenyldpyrromethane and benzaldehyde, while the synthesis of 5,10-Bis(4-methylphenyl)- 10,20-diphenylporphyrin was carried out through 5-phenyldipyrromethane reaction with p-methylbenzaldehyde. Here, TFA was used as acid catalyst and p-chloranil as oxidant. The results of the synthesis mixture was separated by column chromatography with the eluent mixture of n-hexane :ethyl acetate (7:1). Purple fraction was analyzed by TLC (thin layer chromatography), and the R, values are 0.43 and 0.50 for tetraphenylporphyrin and 5,10-Bis(4-methylphenyl)-10,20-diphenylporphyrin, respectively. UV-Vis absorption for tetraphenylporphyrin shows a Soret band at 418.5 nrn and four Q bands at 515.5; 550.5; 591.5; and 646.5 nrn. While 5,10-Bis(4-methylphenyl)-10,20-diphenylporphyrin shows a Soret band at 419 nrn and four Q bands at 515; 551; 592.5; and 645.5 nrn. The addition of acid to the synthesized compounds cause protonation of porphyrin rings, then leads to hyperporphyrin effects which observed from UV-Vis absorption and emission spectra. It makes the spectra shift to the longer wavelength. This shift distinguish tetraphenylporphyrin from 5,10-Bis(4-methylphenyl)-10,20-diphenylporphyrin siguificantly.