卟啉及铁卟啉的合成方法研究

Synthesis of p -substituted tetraphenylporphyrins and corresponding ferric complexes with mixed-solvents method

Zhicheng SUN 1,Yuanbin SHE (✉)1,Rugang ZHONG 2

1Institute of Green Chemistry and Fine Chemicals,Beijing University of Technology,Beijing 100124,China 2College of Life Science &Bioengineering,Beijing University of Technology,Beijing 100124,China

©Higher Education Press and Springer-Verlag 2009

Abstract By using mixed-solvents method,five kinds of p -substituted tetraphenylporphyrin compounds [T(p -R)PPH 2,R =NO 2,Cl,CH 3,OCH 3,OH]were synthesized by the condensation of p -substituted benzaldehyde with pyrrole in mixed solvents (propionic acid,acetic acid and nitrobenzene),and corresponding ferric complexes [T(p -R)PPFe III Cl]were synthesized in dimethylformamide.The above free base porphyrins were obtained in 30%–50%yields,metalation yields were up to 90%and total yields of ferric complexes were 27%–50%.Effects of reactive conditions,solvents and oxidants on yields of free base porphyrins were investigated and the relevant mechanism was discussed.Structures of the above porphyrin complexes were characterized by ultraviolet-visible (UV-Vis),infrared (IR)and far infrared (FIR)spectroscopy.

Keywords porphyrin,metalloporphyrin,mixed-solvents,synthesis,characterization

1Introduction

Substituted tetraphenylporphyrin complexes with conju-gated macrocycles have been essential to the study of biomimetic chemistry in recent years [1–5].The porphyrin iron complexes are mostly used for the models of cytochrome P-450in which the dioxygen has been activated by metalloporphyrins under mild conditions [6,7].Based on that,the substituted metalloporphyrins present high catalytic activities and high selectivities in the catalytic oxidation of hydrocarbons without co-reducing reagents.So the catalytic effect of metalloporphyrins on the activity of inert C-H bonds has been given considerable attention [8].

However,the yields of substituted tetraphenylporphyrin complexes are lower and the cost of synthesis is still expensive,which have exceedingly restricted their current applications.Herein,the study on ef ficient synthesis methods for improving the yields of metalloporphyrin complexes is obviously necessary.

Chemists have developed a few synthetic methods to provide convenient access to synthesize substituent tetraphenylporphyrin complexes [9–11].The prevalent method of synthesis involves a mixed aldehyde condensa-tion with pyrrole via Adler method in re fluxing propionic acid [12].Nevertheless,several limitations remain on the scope of synthetic porphyrin chemistry.One of these is the synthesis of porphyrins with only one solvent, e.g.,propionic acid or dimethylformamide,which brings the problems of a higher boiling point and inconsistent polarity [13].Therefore,the porphyrin complexes are often with low yields and the synthetic method is not universal for porphyrin complexes with various substituents.

In this paper,a series of para -substituted tetraphenyl-porphyrin compounds and the ferric complexes [T(p -R)PPFe III Cl]were synthesized by using mixed-solvents method (Scheme 1).Different reaction conditions were investigated and the yields of porphyrin complexes were improved remarkably.This approach proved to be effective for the synthesis of a varity of metalloporphyrins.

2

Experimental

2.1

Reagent and instrument

All chemicals were obtained commercially and used as received unless otherwise noted.Pyrrole was redistilled before use.Dichloromethane was dehydrated.Neutral Al 2O 3was baked at 100°C for 5h.

Ultraviolet-visible (UV-Vis)spectra were obtained on HITACHI U-3010.Infrared (IR)spectra were obtained on

Received September 18,2008;accepted November 10,2008E-mail:sheyb@

Front.Chem.Eng.China 2009,3(4):457–461DOI 10.1007/s11705-009-0169-6