- Nitration of pyrene adsorbed on silica particles by nitrogen dioxide under simulated atmospheric conditions
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Nitration of adsorbed pyrene on silica particles with nitrogen dioxide was studied under condition of room light in a simulated atmosphere. An induction period was present in the nitration process. Nitric acid formed on the silica particles acted as the catalyst, and the reaction proceeded autocatalytically. Electron-donating substituents promoted the reaction, while the electron-attracting substituents diminished it. An electrophilic nitration mechanism involving HNO2+ and HN2O4+ as electrophiles was proposed for the reaction. Nitration of adsorbed pyrene on silica particles with nitrogen dioxide was studied under condition of room light in a simulated atmosphere. An induction period was present in the nitration process. Nitric acid formed on the silica particles acted as the catalyst, and the reaction proceeded autocatalytically. Electron-donating substituents promoted the reaction, while the electron-attracting substituents diminished it. An electrophilic nitration mechanism involving HNO2+ and HN2O4+ as electrophiles was proposed for the reaction.
- Wang, Huimin,Hasegawa, Kiyoshi,Kagaya, Shigehiro
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Read Online
- The nitration of pyrene adsorbed on silica particles by nitrogen dioxide
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Conversion of NO2, HNO2 gas, their mixture and a mixed gas of HNO2 and HNO3 on silica particles was investigated under simulated atmospheric conditions. Both HNO2 and HNO3 were detected as the products from conversion of NO2 on silica particles. However, unlike HNO3, which increased with conversion time, HNO2 underwent an increase-decrease time course due to the increased HNO3 further transformed HNO2 into NO+ on silica particles. Considering the catalytic effect of HNO3 and HNO2 on the nitration of pyrene adsorbed on silica particles by NO2, another electrophilic nitration path, analogous to the one that we previously reported, with NONO2/+ and NONO2/4+ as electrophiles was suggested. The two paths together gave an appropriate explanation for the catalytic effect of HNO2, HNO3 and their mixed gas on the nitration of the adsorbed pyrene by NO2. (C) 2000 Elsevier Science Ltd.
- Wang, Huimin,Hasegawa, Kiyoshi,Kagaya, Shigehiro
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Read Online
- Regioselective Functionalization of 9,9-Dimethyl-9-silafluorenes by Borylation, Bromination, and Nitration
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Despite the utility of 9-silafluorenes as functional materials and as building blocks, methods for efficient functionalization of their backbone are rare, probably because of the presence of easily cleavable C-Si bonds. Although controlling the regioselectivity of iridium-catalyzed direct borylation of C-H bonds is difficult, we found that bromination and nitration of 2-methoxy-9-silafluorene under mild conditions occurred predominantly at the electron-rich position. The resulting product having methoxy and bromo groups can be utilized as a building block for the synthesis of unsymmetrically substituted 9-silafluorene-containing π-conjugated molecules.
- Murai, Masahito,Nishinaka, Naoki,Kimura, Mizuki,Takai, Kazuhiko
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- Regioselective Functionalization of 9,9-Dimethyl-9-silafluorenes by Borylation, Bromination, and Nitration
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Despite the utility of 9-silafluorenes as functional materials and as building blocks, methods for efficient functionalization of their backbone are rare, probably because of the presence of easily cleavable C-Si bonds. Although controlling the regioselectivity of iridium-catalyzed direct borylation of C-H bonds is difficult, we found that bromination and nitration of 2-methoxy-9-silafluorene under mild conditions occurred predominantly at the electron-rich position. The resulting product having methoxy and bromo groups can be utilized as a building block for the synthesis of unsymmetrically substituted 9-silafluorene-containing ?-conjugated molecules.
- Murai, Masahito,Nishinaka, Naoki,Kimura, Mizuki,Takai, Kazuhiko
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p. 5667 - 5676
(2019/05/10)
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- Preparation and characterization of pyrene modified uridine derivatives as potential electron donors in RNA
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Charge transfer across double stranded DNA was observed for the first time about 20 years ago, and ever since it has been the subject of a large number of studies. RNA has been hardly investigated in this regard, which not least is due to the lack of suitably functionalized ribonucleotide building blocks to serve as electron sources upon incorporation into oligoribonucleotides. We have synthesized two uridine derivatives carrying pyrene or dimethylaminopyrene linked to C5 of the nucleobase. The key to successful synthesis was the adaptation of Suzuki-Miyaura conditions to the coupling of the pyrene moiety with the ribonucleoside. Final decoration of the pyrenylated nucleosides with standard 5′-O- and 2′-O-protecting groups and subsequent 3′-O-phosphitylation delivered the building blocks for incorporation into RNA. Spectroscopic analysis of the two pyrenylated uridines and of the accordingly modified oligonucleotides showed that in particular the dimethyaminopyrene functionalized nucleoside is a promising candidate as an electron source for RNA charge transport studies.
- Frommer, Jennifer,Karg, Beatrice,Weisz, Klaus,Müller, Sabine
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p. 7663 - 7673
(2018/11/02)
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- Diphenylpyrenylamine-functionalized polypeptides: Secondary structures, aggregation-induced emission, and carbon nanotube dispersibility
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In this study we prepared - through ring-opening polymerization of γ-benzyl-l-glutamate N-carboxyanhydride (BLG-NCA) initiated by N,N-di(4-aminophenyl)-1-aminopyrene (pyrene-DPA-2NH2) - poly(γ-benzyl-l-glutamate) (PBLG) polymers with various degrees of polymerization (DP), each featuring a di(4-aminophenyl)pyrenylamine (DPA) luminophore on the main backbone. The secondary structures of these pyrene-DPA-PBLG polypeptides were investigated using Fourier transform infrared spectroscopy and wide-angle X-ray diffraction, revealing that the polypeptides with DPs of less than 19 were mixtures of α-helical and β-sheet conformations, whereas the α-helical structures were preferred for longer chains. Interestingly, pyrene-DPA-2NH2 exhibited weak photoluminescence (PL), yet the emission of the pyrene-DPA-PBLG polypeptides was 16-fold stronger, suggesting that attaching PBLG chains to pyrene-DPA-2NH2 turned on a radiative pathway for the non-fluorescent molecule. Furthermore, pyrene-DPA-2NH2 exhibited aggregation-caused quenching; in contrast, after incorporation into the PBLG segments with rigid-rod conformations, the resulting pyrene-DPA-PBLG polypeptides displayed aggregation-induced emission. Transmission electron microscopy revealed that mixing these polypeptides with multiwalled carbon nanotubes (MWCNTs) in DMF led to the formation of extremely dispersible pyrene-DPA-PBLG/MWCNT composites. The fabrication of MWCNT composites with such biocompatible polymers should lead to bio-inspired carbon nanostructures with useful biomedical applications.
- El-Mahdy, Ahmed F. M.,Kuo, Shiao-Wei
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p. 15266 - 15281
(2018/05/04)
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- Method for nitrating aromatic compound by using nitrate under the action of auxiliary agent
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The invention discloses a method for nitrating an aromatic compound by using a nitrate under the action of an auxiliary agent, and provides an aromatic nitro compound preparation method, which comprises: in the presence of an external action and an auxiliary agent, carrying out a nitrating reaction on an aromatic compound and a metal nitrate or a hydrate thereof to obtain the aromatic nitro compound, wherein the external action can cause the physical and/or chemical property change of a substance, the auxiliary agent is a substance having water absorbing ability, the external action can be mechanical force or heating, and the mechanical force can be any one selected from compression, shearing, impacting, friction, stretching, bending and vibration. According to the present invention, the method does not require any solvents so as to avoid the generation of the waste liquid; the acidic substance is not used, such that the treatment is simple after the reaction is completed, and the equipment is not damaged; the added auxiliary agent can be theoretically recycled; and the method has extremely high conversion rate and extremely high selectivity, and can be used for the nitration of conventional aromatic compounds.
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Paragraph 0078; 0079
(2018/09/11)
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- Mechanical force under the action of the nitration of aromatic compounds of nitrate method (by machine translation)
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The invention discloses a mechanical force under the action of the nitration of aromatic compounds of nitrate method. The invention provides a method for preparing aromatic nitro compounds, comprising the following steps: under the action of mechanical force, aromatic compound with a metal nitrate or its hydrate by the nitration reaction, to obtain the aromatic nitro compound; the mechanical fastener is machinery offers can cause material physical and/or chemical nature of the change of the external force. The mechanical force can be compression, shear, impact, friction, tensile, bending and vibration of any kind. The invention has the following advantages: without the use of any solvent, thereby avoiding the waste liquid produced; and without the use of the acidic substance, the reaction is complete after treatment is simple, without any damage to the apparatus; a very high conversion and selectivity, can be applied to the nitration of conventional aromatic compound. (by machine translation)
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Paragraph 0071-0078
(2018/09/11)
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- Synthesizing method of OLED intermediate and semiconductor material 1-hydroxy pyrene
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The invention discloses a synthesizing method of OLED intermediate and semiconductor material 1-hydroxy pyrene. The method comprises the following steps: adding pyrene and a solvent I to a reaction vessel; uniformly stirring; then adding a nitrosation agent; stirring under the temperature of 20-25 DEG C; adding water to the obtained product; separating out a solid; drying the separated-out solid to obtain 1-nitroso pyrene; mixing 1-nitroso pyrene and an alcohol solvent to obtain suspension; charging air or oxygen into the suspension; performing illumination reaction until 1-nitroso pyrene is completely reacted; adding BHT; concentrating under the temperature of 45-50 DEG C until the product is dry; then adding a recrystallizing solvent; heating until dissolved clarification is realized; cooling until the temperature is 20-25 DEG C; filtering; and drying a filter cake to obtain 1-hydroxy pyrene. With the adoption of the method, 1-hydroxy pyrene with purity not less than 99.1% can be obtained.
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Paragraph 0045; 0046; 0047; 0048; 0049
(2019/01/14)
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- Effect of the blocked-sites phenomenon on the heterogeneous reaction of pyrene with N2O5/NO3/NO2
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To clarify whether the blocking reaction sites problem has a significant impact on heterogeneous reactions, experiments contrasting the order of pyrene (PY) particles' exposure to N2O5-O3 or O3-N2O5 in a heterogeneous process were conducted. Additionally, PY particles were exposed to N2O5 (～8 ppm) in the presence of O3 (2.5-30 ppm) in a reaction chamber at ambient pressure and room temperature. Our results show that the phenomenon of blocking reaction sites may be ubiquitous on the surfaces of atmospheric aerosol particles, and the N2O5-initiated ionic electrophilic nitration may be promoted by NO3 radical-initiated heterogeneous reactions on the aerosol particle surface. We also found that the operative reaction mechanism strongly depends on the concentrations of the nitric oxides in the atmosphere. Our results provide an explanation as to why 2-nitropyrene (2-NPY), one of the most ubiquitous nitro-polyaromatic hydrocarbon pollutants that exists in both the gas and particle phases, was not observed in previous experiments on the heterogeneous reactions of PY and N2O5/NO3/NO2.
- Zhang, Peng,Sun, Wanqi,Yang, Bo,Shu, Jinian,Dong, Liang
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p. 10358 - 10364
(2016/02/05)
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- 4-(Pyren-1-ylimino)methylphenol and its silylated derivative as chromogenic chemosensors highly selective for fluoride or cyanide
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Two novel compounds, 4-(pyren-1-ylimino)methylphenol and 4-[(triisopropylsilyl)oxy] phenylmethylenepyren-1-amine) were synthesized. Solutions of 4-(pyren-1-ylimino)methylphenol in dimethyl sulfoxide (DMSO) are colorless, but on addition of cyanide and fluoride they become colored due to the deprotonation of the chemosensor. The system is highly selective toward cyanide with the addition of water. This compound can be solubilized in water with addition of cetyltrimethylammonium bromide above its critical micellar concentration. The pKa of the compound in water was determined as 10.49 ± 0.02 and this value is lowered in micellar medium to 7.49 ± 0.02, which means that only cyanide is sufficiently basic to achieve the deprotonation of the compound. Solutions of 4-[(triisopropylsilyl)oxy]phenylmethylenepyren-1-amine) in DMSO are colorless, but they are colored in the presence of cyanide and fluoride and only cyanide could be detected in DMSO-water mixture. The nucleophilic attack of the anions on the silicon center of the compound releases colored 4-(pyren-1-ylimino)methylphenolate, enabling the detection of nucleophilic analytes.
- Buske, Jonatan L. O.,Nicoleti, Celso R.,Cavallaro, Aluisio A.,Machado, Vanderlei G.
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p. 2507 - 2519
(2016/02/23)
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- Tunable star-shaped triphenylamine fluorophores for fluorescence quenching detection and identification of nitro-aromatic explosives
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Triphenylamine-based fluorophores containing pyrene or corannulene show variable fluorescence quenching sensitivity toward nitro explosives. The most sensitive fluorophore is capable of detecting TNT on the ng cm-2 scale; the array is useful for identifying nitro aromatics.
- Niamnont, Nakorn,Kimpitak, Nattaporn,Wongravee, Kanet,Rashatasakhon, Paitoon,Baldridge, Kim K.,Siegel, Jay S.,Sukwattanasinitt, Mongkol
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supporting information
p. 780 - 782
(2013/02/23)
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- A new processable and fluorescent polydithienylpyrrole electrochrome with pyrene appendages
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A new hybrid compound, namely 1-(pyren-3-yl)-2,5-di(thiophen-2-yl)-1H- pyrrole (SNS-P), was polymerized via both chemical and electrochemical methods. Chemically obtained soluble polydithienylpyrrole (c-PSNS-P) bearing pyrene appendages is a homogeneous and uniform polymer with a number averaged molecular weight of 15,200 g/mol. The polymer exhibits both multi-electrochromic and fluorescent properties. Upon oxidation, the color of electrochemically obtained polymer (e-PSNS-P) changes from yellowish orange to greenish yellow and to green/blue and finally to blue. In addition, the polymer induces yellowish orange (564 nm) and bright orange emission (613 nm) in solution and solid states, respectively.
- Tirke?, Seha,Mersini, Jetmire,?zta?, Zahide,Algi, Melek Pamuk,Algi, Fatih,Cihaner, Atilla
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p. 295 - 301
(2013/04/10)
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- Tuning of n- and p-type reduced graphene oxide transistors with the same molecular backbone
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Play the field: A field-effect transistor using reduced graphene oxides was prepared through the reduction of graphene oxides connected between two electrodes. The use of pyrene with an electron-withdrawing group and an electron-donating group showed the p- and n-doping effects, respectively, while the pyrene backbone with no electron-withdrawing or -donating groups showed no doping effect.
- Lee, Junghyun,Hwang, Eunhee,Lee, Eunkyo,Seo, Sohyeon,Lee, Hyoyoung
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supporting information; experimental part
p. 5155 - 5159
(2012/06/01)
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- Fluorescent and electrochromic polyamides with pyrenylamine chromophore
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A series of novel polyamides with a pyrenylamine chromophore in the backbone were prepared from a newly synthesized diamine monomer, N,N-di(4-aminophenyl)-1-aminopyrene, and various dicarboxylic acids via the phosphorylation polyamidation technique. These polyamides were readily soluble in many organic solvents and could be solution-cast into tough and amorphous films. They had useful levels of thermal stability with glass-transition temperatures in the range of 246-326 °C and 10% weight loss temperatures in excess of 500 °C. The dilute NMP solutions of these polyamides exhibited fluorescence maxima around 522-544 nm with quantum yields up to 30.2%. These polyamides also showed remarkable fluorescence solvatochromism in various solvents. The polymer films showed reversible electrochemical oxidation and reduction accompanied by strong color changes from the yellow neutral state to a purple oxidized state and to an orange reduced state. The anodically electrochromic films had high coloration efficiency (up to 172 cm2 C-1 at 834 nm) and good redox stability, which still retained a high electroactivity after long-term redox cycles.
- Kung, Yi-Chun,Hsiao, Sheng-Huei
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supporting information; experimental part
p. 5481 - 5492
(2011/08/10)
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- Recognition of anions by bis urea based fluorescent receptors
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Three bis urea based acyclic receptors with fixed spacer and varying size of substituents have been synthesized and their binding behavior with different anions are reported along with the selectivity of these receptors towards anions. The fluorescence quenching of the receptors 2 and 3 on binding with anions is also shown. The receptor 1 binds better with Y-shaped AcO-ion whereas receptor 3 binds well with Cl-ion.
- Goswami, Shyamaprosad,Jana, Subrata
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scheme or table
p. 399 - 405
(2011/04/12)
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- Study on the synthesis and molecular recognition of new receptors for selective complexation of carboxylic acids
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A new synthetic method based on the synthesis of unsymmetrical thioureas followed by double S-alkylation reaction by xylylene dibromides was used to obtain isothiouronium receptors. Their binding abilities to acetate, succinate and maleate anions were evaluated by UV-vis spectroscopic titrations in such solvents as water, acetonitrile, methanol and mixtures of acetonitrile/methanol (1:1, v/v). For simple receptor 4 with one isothiouronium group, no selectivity was observed in the complexation of the anions studied. Receptors (R) 5a-c with two thiouronium groups are able to form with all the anions studied (A) not only stable complexes of 1:1 stoichiometry but also other possessing structure of the type AnRm. The most reliable values of stability constants are for systems of the type maleate anion-receptor 5 and acetate-receptor 5b. However, the best selectivity in the mixed solvents is demonstrated by anion-5c system. The study indicates also that particularly 5c is preferred as a chemosensor for the maleate anion. The obtained results suggest that subtle changes in the receptor structure lead to different binding modes towards anions.
- Or?owska, Maja,Mroczkiewicz, Micha?,Guzow, Katarzyna,Ostaszewski, Ryszard,K?onkowski, Andrzej M.
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experimental part
p. 2486 - 2491
(2010/06/14)
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- Pyrene-naftylamide bifluorophore for spectra-converting media
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New bifluorophore containing pyrene as an excitation energy donor and naphtylamide as an acceptor is synthesized and its optical properties are studied. It is founded that excitation spectrum of the bifluorophore is almost the sum of its constituents-pyrene and naftylamide. At the same time, in the luminescence spectrum there only the peak of acceptor luminescence is observed, which indicates the effective radiationless energy transfer from the donor to the acceptor. This is also proved by time resolved measurements of bifluorophore decay. The decay rate was calculated from decay curve and appear to be 0.25 hc-1. The same value obtained from the Foerster's theory is almost by an order as high. It indicates that Foerster's does not applicable in this particular case. Instead, we have to use the electron excitation density functions approach.
- Adadurov, Alexander F.,Gurkalenko, Yurii A.,Zhmurin, Piotr N.
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experimental part
p. 315 - 320
(2011/10/18)
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- Autocatalytic Nitration of Pyrene by Aerated Nitrogen Dioxide in Solution and Comparison with the Nitration on Silica Particles
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The nitration mechanism of pyrene (PYH) by aerating NO2 in solution was studied by varying the factors (concentration of NO2, addition of HNO3 gas and H2O, 1-substituent on PYH, and solvent) affecting the nitration. Only 1-nitropyrene was formed, In acetonitrile, both the decrease in PYH and the increase in 1-nitropyrene depicted sigmoid curves, that is, their changes proceeded abruptly after an induction period, and finally approached to zero, The characteristic feature was reasonably explained by the facts that H+ dissociated from HNO3, accumulated by aerating NO2 into trace water-containing acetonitrile and released by the nitration, acted as an autocatalyst. The nitration proceeded electrophilically based on the 1-substituent effect of PYH, and accelerated with increasing polarity of the solvents. The nitration was studied kinetically and an ionic mechanism involving NO2+ as an electrophile was proposed. The nitration mechanism of PYH in acetonitrile was different from that in the adsorbed water on silica gel.
- Hasegawa, Kiyoshi,Kaneko, Hiroshi,Ogawa, Tatsuya
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p. 147 - 155
(2007/10/03)
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- Pyrene-derived novel one- and two-component organogelators
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A new class of alkyl-chainappended pyrene derivatives 4 - 14 were synthesized and evaluated for their gelation abilities. Depending on the nature of the linking group, these compounds gelated a number of organic solvents, either in the presence or in the absence of the acceptor molecule 2,4,7-trinitrofluorenone (TNF). Compounds with ester, ether, or alkyl linkages gelated a number of hydroxylic and hydrocarbon solvents by means of a charge-transfer interaction with TNF, while compounds with amide, urethane and urea linkers formed gels on their own in a variety of solvents by means of π-π stacking and hydrogen-bonding interactions. The X-ray crystal structure of urethane (S)-12 showed hydrogen-bonding and stacking features, as suggested by the model. The gels obtained were investigated by spectroscopic and electron microscopic techniques which provided structural insights.
- Babu,Sangeetha,Vijaykumar,Maitra, Uday,Rissanen, Kari,Raju
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p. 1922 - 1932
(2007/10/03)
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- Selective nitration of aromatic compounds with bismuth subnitrate and thionyl chloride
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Bismuth subnitrate/thionyl chloride have been found to be an efficient combination of reagents for nitration of a wide range of aromatic compounds in dichloromethane. Phenols, in particular, were easily mononitrated and dinitrated with the reagents by controlling the stoichiometry.
- Muathen, Hussni A.
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p. 593 - 598
(2007/10/03)
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- Nitration of polycyclic aromatic hydrocarbons using a supported catalyst
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We report the use of a catalyst, sulfuric acid supported on silica-gel, as a promising method for facile, high yielding, regioselective syntheses of mononitrated polycyclic aromatic hydrocarbons, 6-nitrochrysene, 1- nitropyrene, 1-nitronaphthalene, 2-nitrofluorene, 3-nitrofluoranthene, and 9- nitroanthracene.
- Smith, Amy C.,Narvaez, Lorena D.,Akins, Bridget G.,Langford, Moses M.,Gary, Thomas,Geisler, Victoria J.,Khan, Farooq A.
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p. 4187 - 4192
(2007/10/03)
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- Phase-transfer catalysis in electrophilic substitution reactions: VIII. Nitration of arenes with sodium nitrite in acid medium under conditions of phase-transfer catalysis
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Nitration of aromatic compounds with nitrous acid was studied under conditions of phase-transfer catalysis. Nitroarenes are formed in the system benzene-aqueous sulfuric acid by the electrophilic mechanism of phase-transfer catalysis. Noncatalytic process sometimes does not occur. The stoichiometry of the reaction depends on the amount of atmospheric oxygen in a closed system.
- Zaraiskii,Kachurin,Velichko,Shur,Tikhonova,Furin
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p. 1039 - 1043
(2007/10/03)
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- Effects of an oxidation catalytic converter and a biodiesel fuel on the chemical, mutagenic, and particle size characteristics of emissions from a diesel engine
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This study was conducted to obtain additional information on exhaust emissions with potential health importance from an indirect injection diesel engine, typical of those in use in underground mines, when operated using a soy-derived, fatty-acid mono-ester (or biodiesel) fuel and an oxidation catalytic converter (OCC). Compared to emissions with the diesel fuel without the OCC, use of the diesel (D2) and biodiesel fuel with the OCC had similar reductions (50-80%) in total particulate matter (TPM). The solid portion of the TPM was lowered with the biodiesel fuel. Particle-associated polynuclear aromatic hydrocarbon and 1-nitropyrene emissions were lower with use of the biodiesel fuel as compared to the D2 fuel, with or without the OCC. Vapor- phase PAH emissions were reduced (up to 90%) when the OCC was used with either fuel. Use of the OCC resulted in over 50% reductions in both particle and vapor-phase-associated mutagenic activity with both fuels. No vapor- phase-associated mutagenic activity was detected with the biodiesel fuel; only very low levels were detected with the D2 fuel and the OCC. Use of the OCC caused a moderate shift in the particle size/volume distribution of the accumulation mode particles to smaller particles for the diesel fuel and a reduction of particle volume concentrations at some of the tested conditions for both fuels. The nuclei mode did not contribute significantly to total particle volume concentrations within the measured particle size range (~0.01-1.0 μm). The biodiesel fuel reduced total particle volume concentrations. Overall, use of this OCC for the engine conditions tested with the biodiesel fuel, in particular, resulted in generally similar or greater reductions in emissions than for use of the D2 fuel. Use of the biodiesel fuel should not increase any of the potentially toxic, health- related emissions that were monitored as part of this study. Detailed information necessary to evaluate impact of using a biodiesel fuel on potentially health-related emissions from a diesel engine typical of those used in many underground mining operations are provided. Compared to emissions with the diesel fuel without the oxidation catalytic converter (OCC), use of the diesel (D2) and biodiesel fuel with the OCC had a similar reductions in total particulate matter (TPM). The solid portion of the TPM was lowered with the biodiesel fuel. Particle-associated polynuclear aromatic hydrocarbon and 1-nitropyrene emissions were lower with use of the biodiesel fuel as compared to the D2 fuel, with or without the OCC.
- Bagley, Susan T.,Gratz, Linda D.,Johnson, John H.,McDonald, Joseph F.
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p. 1183 - 1191
(2007/10/03)
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- Abnormal orientation in nitration of anthracene, pyrene, and perylene with pyridinium nitrate. 2-Nitroanthracene and 4-nitropyrene
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Nitration by undissociated nitric acid which presumably forms at thermolysis (115°C) of pyridinium nitrate in pyridine selectively proceeds with respect to aromatic substrates and nonselectively with respect to various positions in aromatic rings. Whereas in electrophilic nitration forms a single isomer of mononitro products, the process under study yields two mononitro isomers, and nitration occurs only with polycyclic hydrocarbons containing a butadiene fragment included into neighboring rings (anthracene, naphthacene, pyrene, and perylene). On the contrary, benzene and its derivatives, naphthalene, phenanthrene, and triphenylene are not nitrated. Beside pyridinium nitrate as nitrating agents giving two isomeric mononitro arenes from polycyclic compounds are used tetranitromethane in pyridine and ammonium nitrate in a mixture pyridine-acetic anhydride. The side products of the reaction are biaryls, quinones (in particular, with unusually located carbonyl groups), and dyes containing aci-nitro and oxo groups.
- Nefedov
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p. 1165 - 1171
(2007/10/03)
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- Lower Nitrogen Oxide Species as Catalysts in a Convenient Procedure for the Iodination of Aromatic Compounds
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A simple method for the iodination of aromatic compounds, using I- as the iodine source and the O2 and catalytic amounts of NO+BF4- as the oxidant, is presented.The reactions are performed at 25 deg C in CF3COOH/CH2Cl2 or CF3COOH/CH3COOH mixtures and compounds with as different reactivities as the halobenzenes and 1-methoxynaphthalene can be iodinated in very good yields.A set of relative rates, isotope effects, and isomer distributions in accordance with the electrophilic action of an "I+" species are presented.The formation of "I+" is discussed in terms of possible outer-sphere and inner-sphere electron-transfer steps.Aromatic bromination and to a lesser extent chlorination can be performed by using similar methods.
- Radner, Finn
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p. 3548 - 3553
(2007/10/02)
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- Spectroscopic and photochemical properties of mononitropyrenes
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The influence of the nitro group on the aromatic ?-system of pyrene has been studied by comparing the spectroscopic and photochemical properties of the three mononitropyrenes.Whereas the UV and mass spectra of 1- and 4-nitropyrene show an interaction normal for nitro-aromatic compounds, this is not observed for 2-nitropyrene.The lack of interaction is reflected in a UV spectrum very similar to that of pyrene and a mass spectrum with a very low abundance of M-NO.The photochemical behaviour of the three compounds is governed by the degree of interaction. 1-Nitropyrene shows the nitro-nitrite rearrangement leading to 1-hydroxypyrene (88percent) and 1-hydroxy-2-nitropyrene (7percent).The photoproducts of 4-nitropyrene are pyrene (9percent) and unstable products which react with the solvent. 2-Nitropyrene is very stable under photochemical conditions due to lack of interaction.Similarly, the sterically hindered 1-methyl-2-nitropyrene is also very stable towards light.The photochemical nitro-nitrite rearrangement observed for nitro-aromatic compounds was found to be governed by electronic effects.
- Braken-van Leersum, A. M. van den,Tintel, C.,Zelfde, M. van't,Cornelisse, J.,Lugtenburg, J.
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p. 120 - 128
(2007/10/02)
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- Nitration of Polycyclic Aromatic Hydrocarbons by Dinitrogen Tetraoxide. II. Synthetic and Mechanistic Aspects
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Treatment of polycyclic aromatic hydrocarbons by dinitrogen tetraoxide in dichloromethane solution leads to the clean production of mononitro derivatives with high positional selectivity in almost quantitative yields.For substrates less reactive than chrysene the addition of catalytic amounts of acid is required for the reaction to proceed at convenient rates.Being very easily performed, the method should be regarded as the best yet found for the synthesis of small amount of these, in many cases, mutagenic mononitro compounds.From studies on relative reactivities, isomer distributions, and the effect of acid, base and nitrosonium ion on the reaction, a mechanism involving initial attack of a novel electrophile, nitrosated dinitrogen tetraoxide, is proposed.The initially formed ?-complex is suggested to be transformed into the nitro ?-complex via a pathway involving radical pairs, thus explaining the observation by others of CIDNP effects on the reaction path of nitrous acid catalyzed nitration, a reaction proposed to follow the same reaction scheme.
- Eberson, Lennart,Radner, Finn
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p. 343 - 356
(2007/10/02)
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- Preparation of Pure Isomers of Dinitropyrenes
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Isomers of dinitripyrenes (1,3-, 1,6-, and 1,8-dinitripyrenes) uncontamined by the other isomers were prepared from the corresponding diaminopyrenes by oxidation, or nucleophilic substitution with nitrite after diazotization.Keywords: dinitropyrene; 1,3-dinitropyrene; 1,6-dinitropyrene; 1,8-dinitropyrene; diaminopyrene; preparation of nitroarenes.
- Hashimoto, Yuichi,Shudo, Koichi
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p. 1992 - 1994
(2007/10/02)
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- Determination of nitrated polynuclear aromatic hydrocarbons in particulate extracts by capillary column gas chromatography with nitrogen selective detection
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The highly complex matrix of a diesel particulate extract was analyzed for nitrated polynuclear aromatic hydrocarbons (nitro-PAH) by use of fused-silica capillary column GC/thermionic nitrogen-phosphorus (GC/NPD) analysis of HPLC fractions. These samples were found to contain at least 100 nitro-PAH. Positive isomer identification for 17 nitro-PAH has been made utilizing the GC retention times of authentic standards and low- and high-resolution mass spectra as criteria. An additional 45 nitro-PAH were tentatively identified by using one or more of these techniques. Quantitative GC/MS analysis of 1-nitropyrene, 1,3-dinitropyrene, 1,6-di-nitropyrene, and 1,8-dinitropyrene was facilitated by the use of perdeuterated analogues of these compounds as internal standards. Detection limits by the GC/NPD method range between 0. 2 and 0. 5 ppm for the HPLC fractionated samples.
- Paputa Peck,Marano,Schuetzle,et al.
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p. 1946 - 1954
(2007/10/02)
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