- Versatile, concise and convenient process for the commercial scale preparation of highest pure 3,3'5,5'-Tetramethylbenzidine (TMB) and its salts, a chromogenic substrate used in staining procedures in immunohistochemistry and visualizing reagent in enzyme-linked immunosorbent assays
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The present invention relates to a process for the preparation of 3,3′,5,5′-Tetramethylbenzidine represented by formula I, and processes for the preparation of intermediates used in the preparation of 3,3′,5,5′-Tetramethylbenzidine.
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Paragraph 0030
(2021/04/23)
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- Transition Metal-Free Oxidative Coupling of Primary Amines in Polyethylene Glycol at Room Temperature: Synthesis of Imines, Azobenzenes, Benzothiazoles, and Disulfides
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A transition metal-free protocol has been developed for the oxidative coupling of primary amines to imines and azobenzenes, thiols to disulfides, and 2-aminothiophenols to benzothiazoles, offering excellent yields. The advantageous features of the present environmentally benign methodology include the usage of biocompatible and green reaction conditions such as, solvent, room temperature reactions and transition metal-free approach. Moreover, it offers a broader substrate scope.
- Hudwekar, Abhinandan D.,Verma, Praveen K.,Kour, Jaspreet,Balgotra, Shilpi,Sawant, Sanghapal D.
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p. 1242 - 1250
(2019/01/09)
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- A 3, 3 ', 5, 5' - tetramethyl benzidine and its hydrochloride synthesis method (by machine translation)
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The present invention provides a synthetic 3, 3 ', 5, 5' - tetramethyl benzidine and its hydrochloride method, which belongs to the technical field of organic synthesis. In order to 2, 6 - dimethyl aniline as the raw material, first of all through the potassium permanganate oxidation of 2, 2 ', 6, 6' - tetramethyl azobenzene, then concentrated hydrochloric acid and zinc powder for the one-step method of 2, 2 ', 6, 6' - tetramethyl azobenzene reduction, rearrangement, and through processing and getting the 3, 3 ', 5, 5' - tetramethyl benzidine and its hydrochloride. In the present invention the used raw materials are cheap and easily obtained, operation process is simple and convenient, mild reaction conditions, higher yield. (by machine translation)
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Paragraph 0020-0021; 0024
(2019/01/08)
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- Aromatic amine oxidation process for preparing aromatic azobenzene method
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The invention relates to a method for preparing an aromatic azo compound by utilizing aromatic amine oxidation. In the method, air or oxygen serves as an oxygen source, and under the effect of a catalyst, aromatic amine is oxidized into the aromatic azo compound. The method is high in oxidization efficiency and product yield; the air or the oxygen serves as the oxygen source, and the method is economical and environmentally friendly. The product and the catalyst can be separated easily, and the aftertreatment is simple. The catalyst is easy to reuse, and the method has very good application prospect.
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Paragraph 0013; 0017
(2017/10/11)
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- Convenient Electrocatalytic Synthesis of Azobenzenes from Nitroaromatic Derivatives Using SmI2
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The synthesis of azobenzenes has been a long-standing challenge. Their current preparation at a preparative or industrial scale requires stoichiometric amounts of environmentally unfriendly reactants. Herein, we demonstrate that the catalytic use of electrogenerated samarium diiodide (SmI2) could promote, in one-step synthesis, the reduction of nitrobenzenes into azobenzenes in high yields under mild reaction conditions. This catalytic procedure contains many elements satisfying a sustainable chemical process for the preparation of one of the most widely wanted family of chemical compounds. The easy synthetic procedure, and the absence of precious metals, bases, and nonhazardous substances, already makes our catalytic procedure a serious alternative to currently available methods. This is a promising method for the efficient synthesis of both symmetrical and asymmetrical azo compounds with a high functional group tolerance.
- Zhang, Yu-Feng,Mellah, Mohamed
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p. 8480 - 8486
(2017/12/08)
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- The palladium and copper contrast: A twist to products of different chemotypes and altered mechanistic pathways
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A novel contrast in palladium and copper catalysis is revealed to form products of different chemotypes resulting in a phenazine to azoarene twist through an altered mechanistic pathway (from non-radical C-H activation mode of C-N coupling to radical N-N coupling) during the oxidative self-coupling of anilines catalysed by Pd-Ag and Cu-Ag nanoclusters.
- Seth, Kapileswar,Roy, Sudipta Raha,Kumar, Asim,Chakraborti, Asit K.
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p. 2892 - 2896
(2016/05/24)
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- Cathodic reduction of diazonium salts in aprotic medium
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Cathodic reduction of diazonium salts in acetonitrile led to the formation of azobenzenes, in good to moderate yields, and diarylamines as minoritary products. The reactions were carried out at the second reduction potential of the diazonium salts, involving aryl anions in the formation of the products.
- Barba, Fructuoso,Batanero, Belen,Tissaoui, Khalil,Raouafi, Noureddine,Boujlel, Khaled
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experimental part
p. 973 - 976
(2011/11/05)
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- A simple and efficient method for the dehydrogenation of symmetric hydrazo compounds with NaNO2-Ac2O
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Rapid oxidation of eighteen symmetric hydrazo compounds to corresponding azo compounds using NaNO2-acetic anhydride as a novel oxidizing agent under mild condition is reported for the first time.
- Li, Xiaochuan,Wang, Yulu,Wang, Jinye
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p. 677 - 678
(2007/10/03)
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- A simple and efficient method for the dehydrogenation of symmetric hydrazo compounds with NaNo2/NaHSO4·H2O/SiO2
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In this paper, 18 symmetric hydrazo compounds undergo rapid oxidation to corresponding azo compounds using NaNO2/NaHSO4·H2O/SiO2 as a novel oxidising agent under mild conditions for the first time.
- Li, Xiao-Chuan,Wang, Yu-Lu,Wang, Jin-Ye
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p. 540 - 541
(2007/10/03)
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- A novel method. The synthesis of ketones and azobenzenes using supported permanganate
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The heterogeneous use of potassium permanganate, supported on copper(II) sulfate pentahydrate, provides a simple and effective means for oxidizing amines. Primary aliphatic amines, such as sec-butylamine, are oxidized to the corresponding carbonyl compounds in good to excellent yields. Primary aromatic amines, such as 4-chloroaniline, are converted quantitatively into the corresponding azo compounds. Carbon-carbon bond cleavage, which usually occurs when alkylbenzene side chains are oxidized by permanganate under homogeneous conditions, does not occur. Under appropriate reaction conditions carbon-hydrogen bond cleavage at the benzylic position, known to occur under heterogeneous permanganate conditions, is also eliminated. For example, a quantitative yield of bis(2,4,6-trimethylphenyl)diazene is obtained from the oxidation of 2,4,6-trimethylaniline using small amounts of permanganate and copper(II) sulfate pentahydrate.
- Noureldin, Nazih A.,Bellegarde, Jody W.
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p. 939 - 942
(2007/10/03)
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- The preparation of symmetrical azobenzenes from anilines by phase transfer catalyzed method
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Used Galvinoxyl as catalyst, the phase transfer catalyzed method of oxidation of primary amines to symmetrical azobenzenes with a saturated solution of potassium ferricyanide in 2N aqueous potassium hydroxide and dichloromethane is described for the first time in this paper. The reaction has intimate relation with Hammett substituent constants. This report offers an efficient and rapid method to prepare azobenzenes and a possible mechanism is also suggested.
- Wang, Xiao-Yang,Wang, Yu-Lu,Li, Jian-Ping,Duan, Zhi-Fang,Zhang, Zi-Yi
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p. 2271 - 2276
(2007/10/03)
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- Phase transfer catalyzed method to prepare symmetrical azobenzenes from anilines
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Using free radical 4-hydroxy-2,2,6,6-tetramethyl-l-piperidinyolxyl as catalyst, the phase transfer catalyzed method of oxidation of anilines to symmetrical azobenzenes with a saturated solution of potassium ferricyanide in 2N aqueous potassium hydroxide and dichloromethane is described for the first time. The reaction has an intimate relation with Hammett substituent constants. This report offers an efficient and rapid method to prepare azobenzenes, and a possible mechanism is also suggested.
- Wang, Xiao-Yang,Wang, Yu-Lu,Wang, Cai-Lan,Li, Jian-Ping,Wang, Hong,Zhang, Zi-Yi
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p. 971 - 974
(2007/10/03)
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- The Electronic Effect of the Phenylazo and t-Butylazo Groups
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Hammett ?p+-values for arylazo and t-butylazo groups have been determined by measurements of the kinetics of solvolysis of the appropriately substituted arylpropan-2-yl chlorides.They have been found to be considerably more positive than expected and differ significantly from earlier estimates based on the rates of electrophilic attack on azobenzene.An interpretation of the discrepancy has been advanced based on the differing orientations of the azo linkage with respect to the aromatic ring in the transition state.The introduction of methyl groups into positions ortho to the phenylazo and t-butylazo substituents causes a change in character from -I, -R to -I, +R.This is true not only for the solvolysis reaction but also for benzoic acid ionisation.
- Byrne, Christopher J.,Happer, Duncan A. R.,Hartshorn, Michael P.,Powell, H. Kipton J.
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p. 1649 - 1654
(2007/10/02)
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- Photochemistry of cyclopentadienylcobalt 1,4-diaryltetraazadienes. Examples of C-H, C-F, and C-C bond breaking
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Irradiation of (η5-C5H5)Co[(2,4-F2C 6H3)N4(2,4-F2C6H 3)] yields (η5-C5H5)Co[HN(FC6H 3)N(2,4-F2C6H3)] and (η5-C5H5)Co[HN(F2C 6H2)N(2,4-F2C6H3)]. Photolysis of (η5-C5H5)Co{[2,6-(CH3) 2C6H3]N4[2,6-(CH3) 2C6H3]} produces (η5-C5H5)Co{HN[(CH3)C 6H3]N[2,6-(CH3)2C6H 3]}. These photochemical reactions appear to proceed by expulsion of N2 from the unsaturated CoN4 ring to produce a metal dinitrene, which undergoes a rapid intramolecular rearrangement to yield products that contain a coordinated o-benzoquinone diimine ligand. When (η5-C5H5)Co{[2,6-(CH3) 2C6H3]N4[2,6-(CH3) 2C6H3]} is irradiated in cumene solvent, the evolved gas consists of an 0.94:1.0 CH4:N2 mixture. These data are consistent with an aromatic radical substitution process for methyl loss. It is suggested that the transition state necessary for this rearrangement is resonance stabilized, owing to the presence of the cobalt atom and the availability of a low-lying empty nitrogen p(π) orbital; Xα calculations of the hypothetical (η5-C5H5)Co(NH)2 species demonstrate the presence of low-lying empty nitrogen p(π) orbitals in the metal dinitrene. When the ortho substituents are hydrogen, as in (η5-C5H5)CO[(C6H 5)N4(C6H5)], photolysis to (η5-C5H5)Co[HN(C6H 4)N(C6H5)] proceeds without production of H radicals in cumene solvent. Similarities exist between the photochemical reactions of metal-tetraazadiene complexes and their fragmentation pathways in a mass spectrometer.
- Gross, Michal E.,Johnson, Curtis E.,Maroney, Michael J.,Trogler, William C.
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p. 2968 - 2973
(2008/10/08)
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