Preparation of <b> <i>meso</i> </b>-Tetraarylporphyrins Nitrated in Two Neighboring Aromatic Rings

Ostrowski, Stanisław; Łopuszyńska, Beata

doi:10.1081/scc-120026352

Cited by 16 publications

(8 citation statements)

References 22 publications

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“…Porphyrins bearing aryl moieties in meso ‐positions (5, 10, 15, 20) can also be successfully nitrated in these rings. In this case, the only mechanism described in the literature was the electrophilic one [21,88–92,95–101,103] . For the first time, this type of nitration taking place on meso ‐phenyl rings was reported by Kruper et al [88] .…”

Section: Nitration Of Porphyrins In Meso‐aryl Ringsmentioning

confidence: 80%

“…Despite repeated chromatography separation of this mixture into individual compounds was unsuccessful. Later studies did not confirm these results [92,95] . Indeed, 5,10‐bis(4‐nitrophenyl)‐15,20‐diphenylporphyrin ( 97 ) is the major dinitro‐isomer, however its amount in the mixture exceeds even 90%, while 5,15‐bis(4‐nitrophenyl)‐10,20‐diphenylporphyrin ( 98 ) in the isolated mixture was observed in an amount of ca 10%.…”

Section: Nitration Of Porphyrins In Meso‐aryl Ringsmentioning

confidence: 92%

“…The substituents on meso ‐phenyl rings (3‐CH 3 , 3‐OCH 3 , 3‐Cl and other halogens; but not strong electron‐withdrawing groups, e. g . CN, NO 2 ; see Chapter 3.4 ) did not change the site of nitration [21,92,96–98] . They only affect the reaction yield and – in some cases – the ratio of isomers.…”

Section: Nitration Of Porphyrins In Meso‐aryl Ringsmentioning

confidence: 94%

“…In 2018 a paper was published from our group in which the orientation of electrophilic nitration in free‐base meso ‐aryl substituted porphyrins was changed without complexation [37] . Contrary to the previous observations (substitution in meso ‐aryl rings, [21,88–92] described in the following Chapter 4 ), the reaction took place at position β . This was the case after introducing strong electron‐withdrawing groups, e. g .…”

Section: Nitration Of Porphyrin Derivatives At the β‐Positionsmentioning

confidence: 95%

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Nitration of Porphyrin Systems: A Toolbox of Synthetic Methods

Mikus

Łopuszyńska

2020

Chemistry An Asian Journal

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This review addresses nitration reactions of porphyrin derivatives. Simple porphyrins modifications afford valuable intermediates in this area of chemistry. They are useful materials for further transformations, as the NO2 group introduced into parent porphyrin system increases its electrophilic character, thus allowing a broad spectrum of subsequent reactions, e. g. reduction of NO2 to NH2, subsequent diazotisation, nucleophilic substitution of hydrogen (in ortho‐position to NO2), a variety of cyclizations, etc. Such reactions are often utilized in the first steps of the designed syntheses, leading to attractive and useful target porphyrin molecules. This approach (via nitro‐derivatives) allows synthesizing numerous porphyrin‐like compounds of a high degree of complexity, and has thus become one of the methods choice. The substitution by NO2 group can take place at all positions of the porphyrin systems: four meso‐positions (5, 10, 15, 20) and eight positions β (2, 3, 7, 8, 12, 13, 17, 18). The third possibility includes the nitration in meso‐aryl rings attached to positions 5, 10, 15, and 20. The latter derivatives (meso‐aryl substituted ones) are a large, well‐known group of synthetic porphyrins. The nitration reactions described herein follow three various mechanisms: (a) radical, (b) via π‐cation radicals and π‐dications, and (c) electrophilic. All the above cases are discussed in detail. According to our knowledge, this is the first such systematic account concerning these reactions.

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Section: Nitration Of Porphyrins In Meso‐aryl Ringsmentioning

confidence: 80%

Section: Nitration Of Porphyrins In Meso‐aryl Ringsmentioning

confidence: 92%

Section: Nitration Of Porphyrins In Meso‐aryl Ringsmentioning

confidence: 94%

Section: Nitration Of Porphyrin Derivatives At the β‐Positionsmentioning

confidence: 95%

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Nitration of Porphyrin Systems: A Toolbox of Synthetic Methods

Mikus

Łopuszyńska

2020

Chemistry An Asian Journal

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“…Prolonged nitration gave 5,10,15-tris(4-nitrophenyl)-20-phenylporphyrin (XV). The nitration of compound IX and its derivatives with various nitrating agents was studied in detail in [10][11][12]. On the basis of the obtained results it was concluded that meso-and β-positions in meso-phenylporphyrins are deactivated toward electrophilic substitution owing to protonation of the inner nitrogen atoms [12].…”

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confidence: 99%

Phenyl-substituted porphyrins: III. Relative reactivity in the nitration reaction

et al. 2010

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Study on the nitration of phenyl-substituted porphyrins showed that protonation of the porphyrin macroring does not affect the relative reactivity of the meso-and β-positions and phenyl groups. * For communication II, see [1].Like other aromatic compounds possessing a closed conjugated π-electron system, porphyrins are capable of reacting with electrophiles to give the corresponding substitution products. The most interesting and widely known electrophilic substitution reaction is nitration. Nitration of compounds of the porphyrin series was reported for the first time in [2][3][4]. As a result, mesonitro derivatives were isolated even in reactions with porphyrins having no substituents in the β-positions. Treatment of porphyrin (I) with a nitrating mixture gives meso-nitroporphyrin (II), and further nitration of the latter yields 5,10-dinitroporphyrin (III) [5]. A mixture of meso-nitro derivatives V-VIII was obtained by nitration of octaethylporphyrin IV [6,7]. First attempts to perform electrophilic nitration of meso-tetraphenylporphyrin IX were unsuccessful. Treatment of IX with a nitrating mixture over a period of 9.5 h resulted in the formation of dihydroxyporphodimethene X, presumably through intermediate ipso-nitration product XI [8] (Scheme 1). Kruper et al. [9] succeeded in nitrating compound IX by treatment of its solution in methylene chloride or chloroform with fuming nitric acid (d = 1.53 g/cm 3 ). The nitration occurred at the para-position of one of phenyl substituents and afforded 5-(4-nitrophenyl)-10,15,20-triphenylporphyrin (XII) (Scheme 2). Further nitration (by increasing the amount of nitrating agent) led to the formation of a 2 : 1 mixture of isomeric 5,10-and 5,15-bis(4-nitrophenyl)-porphyrins XIII and XIV. Prolonged nitration gave 5,10,15-tris(4-nitrophenyl)-20-phenylporphyrin (XV). The nitration of compound IX and its derivatives with various nitrating agents was studied in detail in [10][11][12]. On the basis of the obtained results it was concluded that meso-and β-positions in meso-phenylporphyrins are deactivated toward electrophilic substitution owing to protonation of the inner nitrogen atoms [12]. Compound XVI was not isolated.The goal of the present study was to compare the reactivity of the meso-and β-positions in the porphyrin

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