Protoporphyrin IX Dimethyl Ester is a derivative of Protoporphyrin IX (P839138), which is an important precursor to biologically essential prosthetic groups such as heme, cytochrome c, and chlorophylls.
The crude dimethyl ester (1g) in CHCl3 (200 mL) is mixed with pet ether (b 70-90o, 600mL), and any porphyrin (m > 260o) which is insoluble in this mixture is filtered off. The filtrate is passed through a column of CaCO3 [from CaCO3 (130g) which is kept overnight in a mixture of CHCl3/pet ether (b 70-90o, 1:3), and the slurry is poured into a glass tube (2.5 x 26cm) to form the column]. After all the filtrate is applied, the column is eluted with a solution of CHCl3/pet ether (b 70-90o, 1:3). All the coloured eluates are collected, evaporated at room temperature in a vacuum to give a residue (0.8g), m 208-211o. The residue (0.8g) in CHCl3 (66mL) is heated briefly to its boiling point, then boiling MeOH (198mL) is added immediately to it. The mixture is allowed to cool to room temperature, refrigerated for 2days and the solid is filtered off. The solid is washed on the filter funnel with CHCl3/MeOH (1:9, 50mL) and dried at 50o/vacuum (yield 0.62-0.66g). It can also be recrystallised by dissolving in as little hot dry *C6H6 as possible and left overnight at 20o, m 228-230o. It has also been purified by dissolving (0.4g) in CHCl3 (33mL) by boiling for a few minutes, then diluting with boiling MeOH (100mL) and refrigerating for 2days. The crystals are collected, washed with CHCl3/MeOH (1:9) and dried at 50o in a vacuum (yield 0.3g). The UV has max at 631, 576, 541, 506 and 407nm in CHCl3 and 601, 556 and 406nm in 25% HCl. [Ramsey Biochemical Preparations 3 39 1953, Beilstein 26 III/IV 3052.]
