- Preparation and antibacterial activity of mixed ligand complexes of Co(II), Ni(II), Cu(II) and Cd(II) derived from 1-phenylazo-2-naphthol and salicylaldehyde
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The mixed ligand complexes of Co(II), Ni(II), Cu(II) and Cd(II) have been synthesized by using 1-phenylazo-2-naphthol as primary ligand and salicylaldehyde as secondary ligand. All the prepared complexes were identified and confirmed by elemental analyses (C, H and N), molar conductance measurements, infrared, electronic absorption and electron paramagnetic resonance. The elemental analysis data suggest that the stoichiometry of the complexes to be 1:1:1[M: L1: L2] ratio. The molar conductance measurements of the complexes indicate their non-electrolytic nature. The infrared spectral data showed the coordination sites of the free ligand with the central metal ion. The electronic absorption spectral data revealed the existence of an octahedral geometry for Co(II) and Cd(II) complexes and a square planar geometry for Ni(II) and Cu(II) complexes. The electron paramagnetic resonance spectra of the Co(II) and Cu(II) complexes showed the existence a paramagnetic phenomenon and supported their geometrical structures which confirmed by the electronic absorption spectra. The ligands and mixed ligand complexes have been tested on antibacterial activity against three strains of pathogenic bacteria such as Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa.
- Sharif,El-Tajoury,Elamari
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Read Online
- Relative strength of the intramolecular hydrogen bonding in 1-phenylazo-naphthalen-2-ol and 1-phenyliminomethyl-naphtahlen-2-ol
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The relative strength of the intramolecular hydrogen bonding (IHB) in the title compounds has been investigated by means of ab initio quantum chemical calculations, UV-Vis spectral study and linear solvation energy relationship analysis (LSER) of the obtained tautomeric constants. It has been found that in acetone (and in all used solvents with substantial proton acceptor abilities) the tautomeric constant in the azonaphthol compound is lower than could be expected. The fact is explained with the breakage of the IHB and the coexistence of closed and open enol tautomers. Copyright
- Nedeltcheva, Daniela,Antonov, Liudmil
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Read Online
- A CONTINUOUS PROCESS FOR THE SYNTHESIS OF AZO DYES INVOLVING IN-SITU GENERATION OF DIAZONIUM SALTS
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The present disclosure provides a continuous process for the synthesis coupled compounds of diazonium salts including azo dyes involving in-situ generation of diazonium salts. It further discloses a set up to carry out the process for the synthesis of coupled compounds of diazonium salts.
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Paragraph 0056
(2021/05/21)
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- One-pot synthesis of azo compounds in the absence of acidic or alkaline additives
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A one-pot method for the synthesis of azo compounds by the reaction of β-naphthol with aryl amines using t-BuONO as the nitrosonium source in DCM at room temperature was developed. This method features mild reaction conditions, a simple experimental procedure, and is free of acidic or alkaline additives.
- Cheng, Xin-Wang,Duan, Pan,Liu, Ting-Ting,Yan, Jiao-Zhao,Zeng, Yao-Fu
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p. 486 - 490
(2020/10/22)
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- Continuous flow solvent free organic synthesis involving solids (reactants/products) using a screw reactor
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Here we report for the first-time various organic transformations such as aldol condensation, oxidation, nucleophilic substitutions, protection, acylations and coupling reactions using a mechanochemical approach at a controlled temperature using a single synthesis platform. Almost minimal solvents or solvent-free conditions are used, making it a very efficient and clean synthesis of various products. A jacketed screw reactor when operated at different temperatures (0 °C to 160 °C) and over a range of rotation speeds for changing the residence time (15 s-300 s) helped to achieve maximum conversion. This approach is also extended to the synthesis using substrates having different substitutions, heterocycles and steric hindrance.
- Sharma, Brijesh M.,Atapalkar, Ranjit S.,Kulkarni, Amol A.
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supporting information
p. 5639 - 5646
(2019/10/22)
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- Electronic and spectral studies of some five coordinate complexes of copper (II)
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1-phenylazo-2-nephthol has been synthesized and used for complexation with Cu(II) metal ion along with pyridine, α-picoline, β-picoline, γ-picoline and water as secondary ligands. On the basis of elemental analysis and molar conductivity complexes were formulated as CuL2X [Where L is the prime ligand i.e 1-phenyl-azo-2-nephthol and X is the secondary ligand i.e. pyridine, α-picoline, β-picoline, γ-picoline and H2O.] The magnetic moment of these complexes (1.80-1.83 BM) indicates that these complexes are magnetically dilute. The appearance of 3 bands in the electronic spectra of complexes rules out the trigonal bipyramidal (D3h) symmetry arround Cu(II) ion in these complexes rather the electronic spectra favours square pyramidal (C4V) symmetry of these five coordinate complexes. The highest value of 10Dq clearly indicates the greater coordinating ability of α-picoline than pyridine, β-picoline and γ-picoline.
- Kumar, Birendra,Rani, Rekha,Prasad, Dayanand,Singh, Praveen Kumar,Kumar, Amit,Sharma, Shivadhar
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p. 1463 - 1468
(2019/09/06)
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- A quantitative one-pot synthesis method for industrial azo pigments with recyclable wastewater
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Most industrial azo pigments are synthesized by diazotization in one pot and then coupling in another. This two-pot process has been transformed into a one-pot method by adding granular PTFE (polytetrafluoroethylene) to a mechanically agitated aqueous mixture of NaNO2, HCl, a diazo component and a coupling component. This method avoids the step of using a base or a surfactant to dissolve the coupling component. The reactions were fast and quantitative. The granular PTFE, wastewater and excess HCl were then reused 11 times without deteriorating the reaction rate and product purity. Altogether, 22 industrial pigments and 3 azo compounds were synthesized and the reaction can produce up to 22.7 g of product in the laboratory. Some reactions require less than 2 equiv. of HCl and a mechanism explaining this is proposed. In addition, an o-nitro group effect is advanced to explain the differences in coupling reaction rates for o-, m- and p-nitroaniline.
- Feng, Guangyuan,Zhu, Meiling,Liu, Lei,Li, Chunbao
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supporting information
p. 1769 - 1776
(2019/04/08)
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- Unusual fluorescence of: O-phenylazonaphthol derivatives with aggregation-induced emission and their use in two-photon cell imaging
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o-Phenylazonaphthol (o-PAN) derivatives including 6-bromo-1-((4-bromophenyl)diazenyl)naphthalen-2-ol (AN-Br-OH) and 1-phenylazo-2-naphthol (AN-OH, known as Sudan I (Color Index 12055)) were synthesized to investigate their fluorogenic behaviors, in which their aggregated-induced emission (AIE) is reported. The o-PANs showed a two-photon absorption. The protection of hydroxyl groups in o-PANs was used for fluorescence imaging of esterase-expressed HepG2 cells, which is potentially suitable for sensing and two-photon cell imaging applications.
- Yoon, Yeoju,Jo, Seonyoung,Park, Sang Jun,Kim, Hwan Myung,Kim, Dongwook,Lee, Taek Seung
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supporting information
p. 6747 - 6750
(2019/06/17)
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- Mild preparation method for structural analogs of Sudan I
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The invention discloses a mild preparation method for structural analogs of Sudan I, and belongs to the technical field of organic chemistry. According to the method, dehydrogenation of N'-p-toluenesulfonyl aromatic hydrazine is promoted by utilizing alkali and oxygen in air to form an aryl diazo compound in situ; then a series of 1-aryl azo-2-naphthol Sudan I analogs are prepared by coupling with2-naphthol. By adopting the method disclosed by the invention, the strategy of producing an explosive intermediate in situ is used, so that 1-aryl azo-2-naphthol is conveniently and safely synthesized. The mild preparation method disclosed by the invention is mild in reaction conditions, wide in substrate applicability, simple and convenient to operate, lower in cost, less in by-products, high inproduct purity, and easy to separate and purify and can be suitable for relatively-large-scale preparation.
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Paragraph 0033-0035
(2018/07/30)
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- Method used for synthesizing azo compound using solid particle one kettle method
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The invention relates to a method used for synthesizing an azo compound using solid particle one kettle method. The method comprises following steps: solid particles are introduced into a reaction container, an inorganic acid, an aromatic primary amine, sodium nitrite, water, and a coupling component are added, mechanism stirring is carried out, when the reaction is monitored to be finished, filtering and rinsing are carried out, and the obtained filter cake is a finished product; or the solid particles are introduced into the reaction container, the inorganic acid, the aromatic primary amine,sodium nitrite, and water are added, mechanical stirring is carried out, after complete conversion of the aromatic primary amine, the coupling component is added, mechanical stirring is carried out,when the reaction is monitored to be finished, filtering and rinsing are carried out, and the obtained filter cake is a finished product. The solid particles are preferably selected from polytetrafluoroethylene particles, haw seeds, or stainless steel sand. The solid particles are added into the reaction system to promote reaction, no pre-heating or alkali adding dissolving of diazo components orthe coupling component is needed; most reaction is finished in 1h; reaction time is short; product quality is high; and reaction filtrate and excess inorganic acid can be recycled for a plurality of times.
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Paragraph 0107; 0108; 0109
(2019/01/07)
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- A concept for stimulated proton transfer in 1-(phenyldiazenyl)naphthalen-2-ols
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A series of aryl azo derivatives of naphthols (1–3) were studied by means of UV–Vis and NMR spectroscopy in different solvents as well as by quantum chemical calculations and X-ray analysis. Previous studies have shown that Sudan I (1) exists as a tautomeric mixture. The effect of the solvents is minimized by the existing intramolecular hydrogen bond. Therefore, the influence on the tautomeric state in structurally modified 1 has been investigated. Structure 2 contains an additional OH-group, which deprotonates easily and affects the position of the tautomeric equilibrium by changing the electronic properties of the substituent. The implementation of a sidearm in 3 creates a condition for competition between the nitrogen from the azo group and from the piperidine unit for the tautomeric proton. In this case the use of acid as a stimulus for controlling the tautomeric process was achieved.
- Hristova,Deneva,Pittelkow,Crochet,Kamounah,Fromm,Hansen,Antonov
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- New generation of nitrite functionalized star-like polyvinyl imidazolium compound: Application as a nitrosonium source and three dimensional nanocatalyst for the synthesis of azo dyes
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The compounds with three-dimensional and ionic structures have attracted considerable attentions because of their unique characteristics as a drug carrier and catalyst. Star-like poly ionic compounds are a new generation of three-dimensional structures which have both; the exclusive ionic features and three-dimensional structures. Recently, we reported the synthesis of diazonium salts from aniline derivatives using carboxyl and nitrite functionalized graphene quantum dots. Methods: Nitrite-functionalized star-like polyionic (NFSP) compound was synthesized as a new generation of three-dimensional nanocatalyst. Herein, the use of NFSP as an efficient reagent and nanocatalyst for the diazotization of aniline derivatives and subsequent synthesis of azo dyes via the reaction with active phenolates under solvent-free conditions was reported. Results: In order to demonstrate the positive impact of NFSP efficiency, the reaction times and yields of the products were compared with other methods and catalysts which have been reported previously. The brilliant performance of NFSP can be ascribed to multifunctional reagent and also trapping the ingredient within catalyst cavities. Conclusion: A highly effective and cost-effective method has been developed for the preparation of azo dyes. In reported method, new three-dimensional catalyst with highly ionic characteristic and multifunctional nitrosonium source is available. These special features reduced the required amount of catalyst, reaction time and also increased the efficiency of catalyst.
- Shomali, Ashkan,Valizadeh, Hassan,Noorshargh, Saeideh
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p. 409 - 418
(2017/07/24)
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- A method for continuously preparing azo dye in micro-reactors
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The invention discloses a method for continuously preparing azo dye in micro-reactors in the field of dye synthesis. The azo dye is prepared by firstly subjecting a sodium nitrite solution, an aromatic primary amine and an inorganic acid to a diazotization reaction at room temperature in a first micro-reactor to generate an aromatic primary amine diazonium salt; and then subjecting the aromatic primary amine diazonium salt and a coupling component to a coupling reaction in a second micro-reactor to generate the azo dye. Continuous preparation of the azo dye is achieved by utilizing the micro-reactors, a process is simple, a reaction period is short, and a reaction process can be easily monitored and controlled. Addition of an excessive amount of the sodium nitrite and the coupling agent to increase the reaction speed is not required so that raw materials are saved and the method is environmentally friendly. Reaction liquid in the micro-reactors achieves high-speed collision mixing, a uniform reaction environment is formed immediately, the reaction efficiency is high, and the yield and quality of a reaction product are greatly improved.
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Paragraph 0057-0063
(2018/04/01)
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- Nano-CuFe2O4-supported sulfonic acid as a novel and recyclable nanomagnetic acid for diazotization of aromatic amines: efficient synthesis of various azo dyes
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Abstract: A novel heterogeneous sulfonic acid functionalized nanomagnetic CuFe2O4 was successfully prepared and characterized by analyzing different obtained data including Fourier transform infrared spectroscopy, X-ray powder diffraction, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, thermogravimetric analysis, dynamic light scattering and vibrating sample magnetometer. Then the novel acidic reagent was examined in synthesis of various azo-containing compounds from coupling of aryl diazonium ferrite sulfate salts with aromatic and non-aromatic compounds. The procedure starts by diazotization of aromatic amines with NaNO2 and wet CuFe2O4–SO3H and then coupling reaction of aryl diazonium ferrite sulfate salts with appropriate reagent. The prepared nano-solid acid showed high activity in synthesis of variety of aryl diazonium salts. In addition the as-prepared aryl diazonium ferrite sulfate salts are stable at room temperature for many hours and reacted efficiently in coupling reactions of aryl diazonium salts. All the azo dyes are synthesized in high yields and simple reaction conditions at room temperature. Moreover, the nanomagnetic solid acid was easily recovered from the reaction mixture and reused five runs without significant loss of activity. Graphical Abstract: [Figure not available: see fulltext.]
- Nemati, Firouzeh,Elhampour, Ali,Natanzi, Mahshid B.,Sabaqian, Samaneh
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p. 1045 - 1054
(2016/05/02)
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- Convenient and rapid diazotization and diazo coupling reaction via aryl diazonium nanomagnetic sulfate under solvent-free conditions at room temperature
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For the first time, nanomagnetic-supported sulfonic acid is used for conversion of several types of aromatic amine, containing electron-withdrawing groups as well as electron-donating groups to the corresponding azo dyes in excellent yield. The synthesis of these compounds is described by the sequential diazotization-diazo coupling of various aromatic amines with sodium nitrite, nanomagnetic supported sulfonic acid and coupling agents under solvent-free conditions at room temperature. This new method offers several advantages including short reaction time, mild reaction conditions, avoidance of harmful acids, and simple work-up procedure. More importantly, aryldiazonium salts supported on magnetic nanoparticles (aryl diazonium nanomagnetic sulfate) were sufficiently stable to be kept at room temperature in the dry state.
- Koukabi, Nadiya,Otokesh, Somayeh,Kolvari, Eskandar,Amoozadeh, Ali
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- The in situ generation and reactive quench of diazonium compounds in the synthesis of azo compounds in microreactors
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In this paper, a micro-fluidic optimized process for the continuous flow synthesis of azo compounds is presented. The continuous flow synthesis of Sudan II azo dye was used as a model reaction for the study. At found optimal azo coupling reaction temperature and pH an investigation of the optimum flow rates of the reactants for the diazotization and azo coupling reactions in Little Things Factory-MS microreactors was performed. A conversion of 98% was achieved in approximately 2.4 minutes and a small library of azo compounds was thus generated under these reaction conditions from couplers with aminated or hydroxylated aromatic systems. The scaled up synthesis of these compounds in PTFE tubing (i.d. 1.5 mm) was also investigated, where good reaction conversions ranging between 66-91% were attained.
- Akwi, Faith M.,Watts, Paul
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p. 1987 - 2004
(2016/10/05)
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- Carboxyl and nitrite functionalized graphene quantum dots as a highly active reagent and catalyst for rapid diazotization reaction and synthesis of azo-dyes under solvent-free conditions
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Carboxyl and nitrite functionalized graphene quantum dots was prepared from carboxyl and hydroxyl functionalized graphene quantum dots using NaNO2 in the absence of mineral acids. This functional group conversion was confirmed by FT-IR spectroscopy, photoluminescence and X-ray diffraction. The carboxyl and nitrite functionalized graphene quantum dots was used as an effective nitrosonium ion source and reusable catalyst for the efficient diazotization of a variety of arylamines without using any additional acid. Subsequent azo-coupling of these freshly prepared diazonium salts with a range of active aromatic compounds led to the requisite azo-dyes in excellent yields in very short reaction times with a simple experimental procedure.
- Valizadeh, Hassan,Shomali, Ashkan,Nourshargh, Saideh,Mohammad-Rezaei, Rahim
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p. 522 - 528
(2015/03/18)
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- An environmentally friendly approach to the green synthesis of azo dyes in the presence of magnetic solid acid catalysts
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A solvent-free, efficient and green approach for the synthesis of azo dyes has been developed by the diazo coupling reactions of aromatic amines with β-naphthol in the presence of sulfonic acid functionalized magnetic Fe3O4 nanoparticles (Fe3O4@SiO2-SO3H) by a grinding method at room temperature. This green methodology aims to overcome the limitations and drawbacks of the previously reported methods such as low temperature, use of acids, alkalis and toxic solvents, instability of diazonium salts at room temperature, modest yields, and long reaction times. Moreover, the attractive advantages of the process include mild conditions with excellent conversions, simple product isolation process, inexpensive procedure and recyclability of the magnetic catalyst. This journal is
- Safari, Javad,Zarnegar, Zohre
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p. 17738 - 17745
(2015/06/15)
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- Substituent effect on the tautomerization of 1-arylazonaphthalen-2-ols by mass spectrometric analysis
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An electron-ionization (EI) mass spectra of a series of 1-arylazonaphthalen-2-ols was obtained for studying the substituent effect on the fragmentation. The correlation between the ratio, molecular ion and fragment ion, and Hammett's constants is applied to examine the effect of the substituent on the fragmentation. The negative correction between the ratio, Imolecular ion/(I171amu + I143amu + I115amu), and Hammett's constants indicates an electron-withdrawing group destabilized the molecular ion. An unusual long-range hydrogen transfer demonstrates an important role in the fragmentation process Mass spectra of a series of 1-arylazonaphthalen-2-ols were obtained for studying the substituent effect on the fragmentation. The correlation between the ratio of molecular ion and fragment ion, and Hammett's constants is applied to examine the effect of substituent on the fragmentation. The negative correction indicates an electron-with-drawing group destabilized the molecular ion. An unusual long-range hydrogen transfer demonstrates an important role in the fragmentation process.
- Lin, Shaw-Tao,Lin, Lee-Hui,Lin, Yi-Cang,Ding, Mei-Fan
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p. 257 - 262
(2015/03/31)
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- Spectroscopic characterization of some copper(II) complexes
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1-(Phenylazo)-2-naphthol (PANH) has three potential donor sites and thus it acts as a very good chelating agent. This ligand has been used for complexation with CuII ions to synthesize the complexes of general formula Cu(PAN)2Ln, where L = secondary ligands like pyridine, picoline, H2O and n = 0, 1 and 2. These complexes have been characterized by their elemenetal analysis, conductivity measurement, magnetic moment at room temperature, infrared spectra and electronic spectra. The ligand PANH is found to have coordinated through deprotonated phenolic oxygen and azonitrogen forming a six membered chelate with two conjugate π-bonds in chelate ring. The magnetic moment values reveal the mononuclear nature of complexes while their electronic spectra reveal the geometry of the complexes. Cu(PAN)2 complex is found square planar while Cu(PAN)2L and Cu(PAN) 2L2 are found square pyramidal and tetragonally distorted octachedral respectively.
- Rani, Rekha,Ranjan, Rajeeva,Bhattacharjee,Sharma,Suraiya, Afshan
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p. 331 - 336
(2013/06/04)
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- Genetic incorporation of a 2-naphthol group into proteins for site-specific azo coupling
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The 2-naphthol analogue of tyrosine, 2-amino-3-(6-hydroxy-2-naphthyl) propanoic acid (NpOH), has been genetically introduced into proteins in Escherichia coli. This is achieved through the directed evolution of orthogonal aminoacyl-tRNA synthetase/tRNA pairs that selectively charge the target amino acid in response to the amber stop codon, UAG. Moreover, chemoselective azo coupling reactions have been revealed between the 2-naphthol group and diazotized aniline derivatives that are substituted with an electron donating moiety. The coupling reactions required a very mild condition (pH 7) with great reaction rate (less than 2 h at 0 C), high efficiency, and excellent selectivity.
- Chen, Shuo,Tsao, Meng-Lin
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p. 1645 - 1649
(2013/11/06)
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- Fluorescent azo disperse dyes from 3-(1,3-benzothiazol-2-yl)naphthalen-2-ol and comparison with 2-naphthol analogs
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Five novel fluorescent azo disperse dyes were synthesized using different diazotized aromatic amines followed by coupling with 3-(1,3-benzothiazol-2-yl) naphthalen-2-ol. These dyes were characterized by FT-IR, 1H NMR and mass spectroscopy. These azo disperse dyes were applied on polyester and their fastness properties were evaluated. A parallel series of dyes using 2-naphthol in place of benzothiazolyl were made to investigate the effect of benzothiazolyl moiety on the fastness properties. This investigation showed that the dyes containing benzothiazolyl residue have better fastness properties than that of the azo disperse dyes based on 2-naphthol. Effect of pH on photo physical properties was also studied.
- Satam, Manjaree A.,Sekar, N.,Raut, Rajesh K.
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p. 92 - 103,12
(2020/08/20)
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- Nanoparticles of organosilane-based nitrite ionic liquid immobilized on silica for the diazotization of aniline derivatives and subsequent synthesis of azo dyes
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Imidazolium based nitrite ionic liquid containing trimethoxysilyl group was prepared from the reaction of N-methylimidazole and (3-chloropropyl) trimethoxysilane. This ionic liquid was immobilized on silica covalently to give nanoparticles with the imidazolium nitrite moiety remaining intact. The diazotization reaction was performed as a model reaction to examine the activity of these nanoparticles as a nitrosonium source. Excellent performance was exhibited in the diazotization reaction of various aniline derivatives in the presence of HCl under mild heterogeneous conditions (room temperature and short reaction time). In-situ coupling of diazonium salts to a range of tertiary anilines, phenols and naphthols afforded the requisite azo dyes in good yield, using standard experimental procedures.
- Valizadeh, Hassan,Amiri, Mohammad,Hosseinzadeh, Fatemeh
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experimental part
p. 1308 - 1313
(2012/03/27)
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- A new nitrite ionic liquid (IL-ONO) as a nitrosonium source for the efficient diazotization of aniline derivatives and in-situ synthesis of azo dyes
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A new task-specific nitrite containing ionic liquid derived from the O-nitrosation of N-methyl-N-hydroxybutylimidazolinium chloride was synthesized and used as a source of nitrosonium ion to affect the efficient diazotization of arylamines. The diazonium salts thus obtained were coupled, using standard experimental procedures, to a range of tertiary anilines, phenols and naphthols to afford the requisite azo dyes in good yield. The diazotization and subsequent azo-coupling generated the related azo dyes at 0-5 °C in short reaction times with a simple experimental procedure.
- Valizadeh, Hassan,Shomali, Ashkan
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experimental part
p. 1138 - 1143
(2012/03/27)
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- Fe(HSO4)3 as an Efficient Catalyst for Diazotization and Diazo Coupling Reactions
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Diazo coupling reactions of aromatic amines with 2-naphthol in a green, efficient and easy procedure is described. Ferric hydrogensulfate catalyses this reaction in water at room temperature and short reaction time with high yields. The antibacterial activities of the synthesized compounds against four pathogenic bacteria are also investigated.
- Rahimizadeh, Mohammad,Eshghi, Hossein,Shiri, Ali,Ghadamyari, Zohreh,Matin, Maryam M.,Oroojalian, Fatemeh,Pordeli, Parvaneh
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p. 716 - 719
(2013/05/08)
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- Ionic liquid 1-(3-trimethoxysilylpropyl)-3-methylimidazolium nitrite as a new reagent for the efficient diazotization of aniline derivatives and in situ synthesis of azo dyes
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A new ionic liquid 1-(3-trimethoxysilylpropyl)-3-methylimidazolium nitrite was synthesized. This ionic liquid was used as a convenient nitrosonium source in diazotization of arylamines into their corresponding diazonium salts which were converted into their related azo dyes via the in situ azo-coupling with aniline derivatives or phenolic compounds. The diazotization of anilines in this ionic liquid and subsequent azo-coupling generated the related azo dyes in good to excellent yields at 0-5 °C in short reaction times via a simple experimental procedure.
- Valizadeh,Amiri,Shomali,Hosseinzadeh
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experimental part
p. 495 - 501
(2012/07/13)
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- Oxidative and reductive carbodiazenylation of nonactivated olefins
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Procedures for the carbodiazenylation of nonactivated olefins with a wide range of aryldiazonium salts have been developed. The azo compounds obtained can serve as valuable precursors for /?-arylamines (carboamination products), β-amino acids, ketones, and various heterocyclic structures.
- Heinrich, Markus R.,Blank, Olga,Wetzel, Alexander
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p. 476 - 484
(2007/10/03)
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- New dry arenediazonium salts, stabilized to an exceptionally high degree by the anion of o-benzenedisulfonimide
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Arenediazonium o-benzenedisulfonimides 3 (20 examples, yield >90%) were prepared in the dry state by diazotization of aromatic amines with (-pentyl nitrite and o-benzenedisulfonimide in glacial acetic acid or formic acid at 0-5°C. Unlike most diazonium salts in the dry state, salts 3 are very highly stable.
- Barbero, Margherita,Crisma, Marco,Degani, Lacopo,Fochi, Rita,Perracino, Paolo
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p. 1171 - 1175
(2007/10/03)
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- Reaction of Triazene 1-Oxides: Novel Synthesis of Solid Arenediazonium Chlorides
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Treatment of 1,3-diaryltriazene 1-oxides with oxalyl chloride in dry toluene at room temperature gives only solid arenediazonium chlorides; however, treatment with acetyl and benzoyl chlorides does not afford the corresponding diazonium chlorides.
- Mohamed, Shaaban K.,Gomaa, Mohsen A.-M.,Nour El-Din, Ahmed M.
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p. 166 - 167
(2007/10/03)
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- Nitration of Anilinium Ions in Concentrated Sulfuric Acid, Catalyzed by Nitrosonium Hydrogen Sulfate
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Successive treatment of aniline first with nitrosonium hydrogen sulfate and then with nitric acid in concentrated sulfuric acid results in nitration of the anilinium ion in the para position, catalyzed by the nitrosonium salt, along with noncatalytic nitration in the meta and para position.No diazotization of aniline followed by nitration of the benzenediazonium cation occurs.
- Gorelik, M. V.,Lomzakova, V. I.,Khamidova, E. A.,Shteiman, V. Ya.,Kuznetsova, M. G.
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p. 371 - 374
(2007/10/03)
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- para-Bromination of Anilinium Ions in the Presence of Nitrosonium Hydrogen Sulfate in Concentrated Sulfuric Acid
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Aniline and its o-, m-, and N-substituted derivatives are converted to corresponding 4-bromo derivatives in concentrated sulfuric acid under the action of bromine and nitrosonium hydrogen sulfate; in the absence of the latter, no bromination occurs.
- Gorelik, M. V.,Lomzakova, V. I.,Khamidova, E. A.,Shteiman, V. Ya.,Kuznetsova, M. G.,Andrievskii, A. M.
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p. 508 - 512
(2007/10/03)
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- Kinetics and Mechanism of the Diazo Coupling Reaction of Arenediazo Methyl Ethers with β-Naphthol. Part 1. The Rates of Reaction in Nonaqueous Acid Solutions
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Rate data are presented for the diazo coupling reaction of arenediazo methyl ethers with β-naphthol in solutions of dioxane, ethanol, and propan-2-ol acidified with hydrochloric acid at 25 deg C.Over range of HCl concentrations studied, pseudo-first-order rate constants were obtained and the reaction was found to be of first order in diazo ether.The relationship between the observed rate constants (kobs.) and hydrochloric acid concentration (cHCl) was found to be non-linear.Correlations of reaction rates with the Hammett acidity function (H0) and with the Hammett substituent constant (?x) conform with a mechanism in which the slow step is unimolecular decomposition of the protonated diazo ether, DEH(1+), to the coupling entity, the diazonium ion, D(1+), which instantly reacts with β-naphthol to give the azo dye.
- Masoud, Nabil K.,Ishak, Mona F.
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p. 927 - 932
(2007/10/02)
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- TAUTOMERISM IN THE DERIVATIVES OF 1-PHENYLAZO-2-HYDROXY-3-NAPHTHANILIDE
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The spectroscopic criteria for the presence of the azo and quinone hydrazone tautomers were obtained by analysis of the data from electronic spectroscopy and quantum-chemical calculation of the derivatives of 1-phenylazo-2-hydroxy-3-naphthanilide and the fixed forms of the tautomers; the ratio of the azo and quinone hydrazone tautomers depends on the polarity of the solvent; in the transition from chloroform to dimethylformamide the content of the azo form changes from 14.6 to 30.1 percent. "Anomalous" changes in the spectra of 1-arylazo-2-hydroxy-3-naphthanilides compared with the spectra of 1-phenylazo-2-naphthol are brought about by the overlap of the long-wave bands of the azo and quinone hydrazone tautomers with the band for charge transfer from the anilide group to the azo or quinone hydrazone system.
- Zaitsev, B. E.,Sycheva, E. D.,Sheban, G. V.,Lisitsyna, E. S.,Mikhailova, T. A.,et al.
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p. 1556 - 1564
(2007/10/02)
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- 3-Aryl-1-tetrazol-5-yltriazenes, Bench-stable Arenediazonium Ion Synthons: Synthesis of Biaryls and Aryl Halides
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3-Aryl-1-tetrazol-5-yltriazenes have been used as a bench-stable source of diazonium ions for the synthesis of substituted biaryls, aryl halides (iodides, bromides, and chlorides) and azo dyes.The dediazoniation process when induced by trihalogenoacetic acid or acetic acid did not involve free radicals.
- Butler, Richard N.,O'Shea, Paul D.,Shelly, Declan P.
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p. 1039 - 1042
(2007/10/02)
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- A Simple Route for the Synthesis of Chlorosubstituted Arylazobenzenes, Arylazonaphtalenes, and Arylazopyrazoles
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The reaction of arylazophenoles and arylazohydroxypyrazoles (or their tautomer hydrazones) 10, 11, and 15 with POCl3 in dimethylformamide yields chlorosubstituted arylazobenzenes or arylazopyrazoles 12, 13 and 16, resp., in moderate to high yields.The substitution of the OH-group by the Cl-moiety is favoured by acceptor substituents in the aryl fragments ortho- and/or para-linked to the azo group.In case that arylazocompounds derived from resorcinol are used the substitution reaction runs in a stepwise manner giving raise to the formation of o-hydroxy-p-chlorosubstit uted azo compounds 18 primarily and then of dichlorosubstituted azo compounds 19.
- Guenther, R.,Jaehne, E.,Hartmann, H.,Schulze, M.
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p. 945 - 954
(2007/10/02)
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- The Photochemistry of Some Methoxy and Dimethylamino Derivatives of Azoxybenzene
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The photochemistry of the six azoxybenzene derivatives carrying a methoxy and/or a dimethylamino group in positions 4/4' has been examined in alcogols and in benzene and found to lead to different processes.The photo-Wallach rearrangement takes place for all except the disubstituted derivatives.This process involves an intermediate, which either gives back the starting azoxy or is converted to the final o-hydroxy derivative through acid catalysis as well as by the previously reported basic catalysis or via cleavage to diazonium ions, which can be trapped before recombination.Oxygen shift to yield the isomeric azoxy derivative (only one precedent known) is a general, one-way process, leading in every case to the azoxy benzene with the N->O group far from the ring carrying the stronger electron-donating substituent.Differently from the photo-Wallach rearrangement, this process shows little solvent dependence.The dimethylamino derivatives undergo also or exclusively different fragmentations, such as intramolecular hydrogen abstraction and cleavage of either the N=N or the C-N bond.The solvent and substituent effect upon electronic spectra, reaction quantum yield, and product distribution are discussed.The photochemistry is attributed to a ?,?* state with strong internal charge transfer.
- Albini, Angelo,Fasani, Elisa,Moroni, Micaela,Pietra, Silvio
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- The Reaction of Diazonium Ion Generated from α-Azohydroperoxide with Phenols. The Isolation and Reaction of Diazoether Intermediate
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The reaction of benzenediazonium ion generated from α-azohydroperoxide with 1-naphthol gave a diazoether which rearranged to 2- and 4-phenylazo-1-naphthols.
- Tezuka, Takahiro,Ando, Setsuo,Wada, Toshinori
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p. 1667 - 1670
(2007/10/02)
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- GENERATION OF ARENEDIAZONIUM ION FROM MOLECULAR COMPLEX OF α-AZOHYDROPEROXIDE WITH SOLVENTS. A NEW ROUTE FOR DIAZONIUM ION
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Arenediazonium ions are generated from molecular complexes of α-azohydroperoxides with solvents (crystals or oils) under anhydrous conditions, when the solvated molecules are removed from these complexes.
- Tezuka, Takahiro,Ando, Setsuo
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p. 1621 - 1624
(2007/10/02)
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- Nitrosation of 1-Substituted 3-(2-Pyridylmethyl)ureas and Related Compounds
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Nitrosation of 1-methyl- (Ia), 1-(2-chloroethyl)- (Ib) and 1-phenyl-3-(2-pyridylmethyl)urea (Id) with hydrochloric acid and sodium nitrite gave exclusively the corresponding 1-nitrosoureas (IIa,b,d).However, nitrosation of the 1-isopropylurea (Ic) gave a mixture of the 1-nitrosourea (IIc) and the 3-nitrosourea (IIIc).Similar results were also obtained in the nitrosation of 1-substituted 3-(2-pyridyl)ureas (Ie-h).The reaction of the nitrosoureas and m-chloroperbenzoic acid in chloroform gave the N-oxides (IVa-f, Vc,f,g), which were more stable than the nitrosoureas.Keywords-nitrosourea; 1-substituted 3-(2-pyridylmethyl)nitrosourea; 1-substituted 3-(2-pyridylethyl)nitrosourea; nitrosation; antitumor activity
- Kamiya, Shozo,Sueyoshi, Shoko
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p. 1738 - 1742
(2007/10/02)
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