33393-26-9Relevant articles and documents
A convenient, high-yielding, chromatography-free method for the insertion of transition metal acetates into porphyrins
Yao, Shu A.,Hansen, Christopher B.,Berry, John F.
, p. 2 - 6 (2013)
Presented is a quick and efficient method for the insertion of first-row transition metal acetates into 5,10,15,20-tetraphenyl porphyrin, utilizing Soxhlet extraction for the removal of the acetic acid by-product. High yields (>90%) and purity are achieved without requiring chromatographic purification. Basic Mn(III) and Fe(III) acetate may be used, as well as hydrated Co(II), Ni(II), and Cu(II) acetates as starting materials. In the case of Fe, an initial mixture of Fe(TPP)OAc and [Fe(TPP)]2O is formed, which can be quantitatively converted to Fe(TPP)OAc by treatment with acetic acid. The crystal structure of Fe(TPP)OAc is reported, and spectral data for all compounds is presented, including a correction of the literature UV- Vis data for Fe(TPP)OAc. Attempted metalation with basic Cr(III) acetate yielded a mixture of Cr(TPP)OAc and the oxo-bridged dimer. The latter cannot be converted to the desired acetate. No reaction occurred with vanadyl or titanyl acetate under the conditions used.
Stereoelectronic effects of the meso-substituents on the catalytic performance of iron(III) meso-tetraarylporphyrins: Pyridyl and N-methylated pyridyl groups compared to phenyl, 4-methoxyphenyl and 4-sulfonatophenyl ones
Zakavi, Saeed,Mokary Yazdeli, Tahereh
, p. 108 - 115 (2013/02/23)
The activity of a series of iron(III) meso-tetraarylporphyrins (aryl = phenyl, 4-methoxyphenyl, 4-sulfonatophenyl, 2-pyridyl, 3-pyridyl, 4-pyridyl and N-methyl-pyridyl counterparts) in the catalysis of oxidation reactions of olefins with tetra-n-butylammonium periodate (TBAP) or NaIO4 in the presence of imidazole (ImH) has been studied. While the presence of ImH has no effect on the catalytic activity of the Fe-porphyrins containing pyridyl or N-methylated pyridyl substituents at the meso-positions, the catalytic performance of the other Fe-porphyrins significantly increased by the use of ImH in 5:1 molar ratio with respect to the catalyst. As was observed in the comparison of the Mn-porphyrins with pyridyl substituents, the oxidative stability of FeT(4-py)P(OAc) is remarkably higher than that of FeT(2-py)P(OAc) and FeT(3-py)P(OAc). Also, the same order of relative stability was found in the case of the N-methylated analogues. It is noteworthy that N-methylation of FeT(py)P(OAc) complexes led to the substantial decrease in their oxidative stability. Competitive oxidation of cis- and trans-stilbene, provides indirect evidence for the involvement of high valent Fe-oxo porphyrins as well as periodato iron porphyrins as the active oxidant in reactions catalyzed by the used iron porphyrins. However, the involvement of a high valent iron-oxo porphyrin species is more pronounced in the case of FeTPPS4(OAc), FeT(2-py)P(OAc), FeT(3-py)P(OAc), FeT(4-py)P(OAc) and the N-methylated analogues. Also, an unusual preference of trans-stilbene over cis-stilbene was observed in the competitive epoxidation reaction catalyzed by FeT(3-MePy)P(OAc) and FeT(4-MePy)P(OAc) which cannot be described by the cis/trans isomerization. Furthermore, significant cis/trans isomerization observed upon oxidation of cis-stilbene in the reaction catalyzed by FeT(2-MePy)P(OAc) indicates that steric effects due to the presence of methyl groups at the ortho positions of this complex are of minor importance. On the other hand, large differences were observed in the product distribution for oxidation reactions with TBAO performed in dichloromethane and aqueous solvent. In spite of the lack of close correlation between the catalytic activity of the Fe-porphyrins and the electronic properties of the meso-substituents, in comparison with the corresponding Mn-porphyrins, there is a better correlation between the catalytic activity of the Fe-porphyrins and the electronic effects of the meso-groups.
