Octaethylporphyrin

Last updated
Octaethylporphyrin
H2octaethylporphyrin.png
Names
Other names
2,3,7,8,12,13,17,18-Octaethyl-21H,23H-porphine
Identifiers
3D model (JSmol)
379798
ChEBI
ChemSpider
EC Number
  • 220-243-8
PubChem CID
UNII
  • InChI=1S/C36H46N4/c1-9-21-22(10-2)30-18-32-25(13-5)26(14-6)34(39-32)20-36-28(16-8)27(15-7)35(40-36)19-33-24(12-4)23(11-3)31(38-33)17-29(21)37-30/h17-20,37,40H,9-16H2,1-8H3/b29-17-,30-18-,31-17-,32-18-,33-19-,34-20-,35-19-,36-20-
    Key: HCIIFBHDBOCSAF-MUZKIALCSA-N
  • CCC1=C(C2=CC3=NC(=CC4=C(C(=C(N4)C=C5C(=C(C(=N5)C=C1N2)CC)CC)CC)CC)C(=C3CC)CC)CC
Properties
C36H46N4
Molar mass 534.792 g·mol−1
Appearancepurple solid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Octaethylporphyrin (H2OEP) is an organic compound that is a relative of naturally occurring heme pigments. The compound is used in the preparation of models for the prosthetic group in heme proteins. It is a dark purple solid that is soluble in organic solvents. As its conjugate base OEP2-, it forms a range of transition metal porphyrin complexes. When treated with ferric chloride in hot acetic acid solution, it gives the square pyramidal complex Fe(OEP)Cl. [1] It also forms the square planar complexes Ni(OEP) and Cu(OEP).

Contents

Saturated solution of H2OEP in dichloromethane. H2OEP in DCM.jpg
Saturated solution of H2OEP in dichloromethane.

Contrast with other porphyrins

Unlike complexes of the naturally occurring porphyrins, OEP complexes have four-fold symmetry, which simplifies spectroscopic analysis. In contrast to tetraphenylporphyrin and related analogues, H2OEP features unprotected meso positions. In this way, it is a more accurate model for naturally occurring porphyrins.

Synthesis

H2OEP is prepared by condensation of 3,4-diethylpyrrole with formaldehyde. The pyrrole precursor may be synthesised by a Barton-Zard reaction of ethyl isocyanoacetate and 3-nitro-3-hexene; the latter can be generated in situ by elimination of acetic acid from 4-acetoxy-3-nitrohexane. Both the elimination and cyclicization reactions require an equivalent of a non-nucleophilic base such as diazabicycloundecene. [2]

References

  1. ↑ Chang, C. K.; DiNello, R. K.; Dolphin, D. (1980). "Iron Porphines". Inorg. Synth. 20: 147. doi:10.1002/9780470132517.ch35.
  2. ↑ Sessler, Jonathan L.; Mozaffari, Azadeh; Johnson, Martin R. (1992). "3,4-Diethylpyrrole and 2,3,7,8,12,13,17,18-Octaethylporphyrin". Org. Synth. 70: 68. doi:10.15227/orgsyn.070.0068.
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