- Sustainable and recyclable palladium nanoparticles–catalyzed reduction of nitroaromatics in water/glycerol at room temperature
-
Palladium nanoparticles with unique catalytic activity and high stability are synthesized. These nanoparticles exhibit excellent catalytic reduction activity for nitroaromatics in green solvents in the presence of H2 at ambient pressure and temperature. The prominent advantages of this nanotechnology include low consumption of catalyst, excellent chemoselectivity, high reusability of the catalyst, and environmentally green solvents.
- Chen, Jin,Dai, Bencai,Liu, Changchun,Shen, Zhihao,Zhao, Yongde,Zhou, Yang
-
p. 540 - 544
(2020/07/14)
-
- N,S co-doped hierarchically porous carbon materials for efficient metal-free catalysis
-
Metal-free carbon catalysts with excellent catalytic performance have drawn much research attention recently. Herein, polymer-derived N,S co-doped carbon catalysts (PDNSC-X) with a hierarchically porous structure were facilely prepared by a cost-effective and convenient strategy via carbonization of a N- and S atom-containing polymer precursor and were subsequently used as efficient metal-free catalysts. The catalytic activity of the as-fabricated PDNSC-800 was greater than those of other reported heteroatom-doped carbon catalysts in catalytic reduction of various nitroarenes. The high catalytic activity of PDNSC-800 was related to the synergistic effects of a high surface area, a hierarchically porous structure, abundant N- and S-containing active sites, and defect formation. In addition, the close relationship between the N species (especially pyrrolic N) and high selectivity in metal-free catalytic synthesis was investigated in the reduction of nitroarenes and selective oxidation of ethylbenzene. This study may provide a new strategy to fabricate specific heteroatom-doped metal-free carbon catalysts for environmentally friendly efficient organic transformation.
- Hu, Xiwei,Sun, Xun,Song, Qiang,Zhu, Yangyang,Long, Yu,Dong, Zhengping
-
p. 742 - 752
(2020/02/21)
-
- Co-MOF-Derived Hierarchical Mesoporous Yolk-shell-structured Nanoreactor for the Catalytic Reduction of Nitroarenes with Hydrazine Hydrate
-
Porous nanoreactors demonstrate immense potential for applications in heterogeneous catalysis due to their excellent mass-transfer performance and stability. The design of a simple, universal strategy for fabricating nanoreactor catalysts is of significance for organic transformation. In this study, a nanoreactor with a hierarchical mesoporous yolk-shell structure was successfully prepared by the high-temperature carbonization of a ZIF-67@polymer composite. The core of the resultant Co@ZDC@mC material comprised Co NPs anchored in the ZIF-67-derived carbon framework, while the shell comprised resin-polymer-derived mesoporous carbon. The as-obtained Co@ZDC@mC-700 catalyst enriched reactants, efficiently catalyzed the reaction in the core, and permitted the desorption of the product from the nanoreactor. In the catalytic reduction of nitrobenzene with N2H4?H2O, Co@ZDC@mC-700 exhibited superior catalytic efficiency (TOF=1136.3 h?1). In addition, Co@ZDC@mC-700 exhibited excellent performance for the catalytic reduction of various functionalized nitroarenes, as well as good reusability and recyclability. Hence, a simple, useful approach for fabricating a metal-organic-framework-derived non-noble metal-based yolk-shell nanoreactor for effective catalytic transformation is proposed.
- Yuan, Man,Zhang, Hongbo,Yang, Chen,Wang, Fanhao,Dong, Zhengping
-
p. 3327 - 3338
(2019/07/04)
-
- Pd-Pt/modified GO as an efficient and selective heterogeneous catalyst for the reduction of nitroaromatic compounds to amino aromatic compounds by the hydrogen source
-
In this work, different nitroaromatic compounds were successfully reduced to their corresponding aromatic amines with excellent conversion and selectivity in methanol at 50?°C by using Pd-Pt nanoparticles immobilized on the modified grapheme oxide (m-GO) and hydrogen as the reducing source. The catalytic efficiency of Pd and Pd-Pt loading on the modified GO was investigated for the reduction of various nitroaromatic compounds, and the Pd-Pt/m-GO system demonstrated the highest conversion and selectivity. The catalyst was characterized by different techniques including FT-IR, Raman, UV–Vis, XRD, BET, XPS, FESEM, EDS, and TEM. The metal nanoparticles with the size of less than 10?nm were uniformly distributed on the m-GO. The catalyst could be reused at least five times without losing activity, showing the stability of the catalyst structure. Finally, the efficiency of the prepared catalyst was compared with Pd-Pt/AC, and Pd-Pt/GO catalysts.
- Salahshournia, Hossein,Ghiaci, Mehran
-
-
- Bi-functional catalyst of porous N-doped carbon with bimetallic FeCu for solvent-free resultant imines and hydrogenation of nitroarenes
-
The efficient and stable catalyst applied to the transformation of amines into the corresponding imines and hydrogenation of nitroarenes under mild reaction conditions is reported. The catalytic performance of porous N-doped carbon with FeCu (FeCu@NPC) catalyst are tested by aromatic alcohol-based N-alkylated of amines with solvent-free and hydrogenation of nitroarenes via N2H4·H2O. The results proved that the yield of these two reactions are all over 99.9% under optimum condition. Moreover, the synergistic effect of the catalyst for N-alkylated reaction was investigated through the kinetic study. The catalyst can be easily separated from reaction system by an external magnetism, and can be recycled and reutilized for at least 4 runs with conversions are all over 75%. The study of the catalyst indicated that it was suitable for the reactions in industry. Hence, the catalysis process by the inexpensive metals-based catalyst is green and sustainable.
- Wang, Kaizhi,Gao, Wenbing,Jiang, Pengbo,Lan, Kai,Yang, Ming,Huang, Xiaokang,Ma, Lei,Niu, Fang,Li, Rong
-
-
- Pd-doped Ni nanoparticle-modified N-doped carbon nanocatalyst with high Pd atom utilization for the transfer hydrogenation of nitroarenes
-
Palladium (Pd)-based catalysts with maximum utilization of the Pd atoms are attractive for hydrogenation reactions and conserving Pd resources. Herein, the highly dispersed Ni nanoparticle (NP)-modified mesoporous N-doped carbon (Ni/mCN) was successfully prepared by pyrolyzing a mixture of polyacrylonitrile, melamine and Ni(NO3)2·6H2O. Then, the resulting Ni/mCN material with highly dispersed metallic Ni NPs was treated with Pd(AcO)2, and Pd2+ was spontaneously reduced to metallic Pd by the Ni NPs, affording the PdNi NP-based catalyst (PdNi/mCN). The spontaneous reduction process deposits most of the Pd atoms on the surface of the Ni NPs, thus allowing for the maximum utilization of the noble metal Pd. The prepared mesoporous N-doped carbon support can not only provide more surface area to adsorb reaction substrates, but also enhances the accessibility of the active sites of PdNi NPs. The prepared PdNi/mCN nanocatalyst shows a very high catalytic activity for the transfer hydrogenation of nitroarenes using formic acid as the reductant under ambient conditions in aqueous solution, as compared to other Pd-based catalysts, probably because of the highly dispersed PdNi NPs and the maximum utilization of the Pd atoms, as well as the superior structure of mCN. Moreover, the PdNi/mCN nanocatalyst exhibits excellent recyclability and reusability, and the catalytic activity does not obviously decrease after ten reaction cycles. Therefore, we believe that this study should open a new frontier in the preparation of porous N-doped carbon-supported catalysts with maximum utilization of the noble metals for green and sustainable catalysis.
- Cui, Xueliang,Long, Yu,Zhou, Xia,Yu, Guiqin,Yang, Jin,Yuan, Man,Ma, Jiantai,Dong, Zhengping
-
p. 1121 - 1130
(2018/03/13)
-
- Aminal-based Hypercrosslinked Polymer Modified with Small Palladium Nanoparticles for Efficiently Catalytic Reduction of Nitroarenes
-
Fabrication of heterogeneous catalysts with excellent activity, selectivity and stability is significant for various catalytic applications. Here, we prepared a hypercrosslinked polymer (HCP) via a facile and cost-effective strategy using ferrocenecarboxaldehyde and melamine as building blocks. Then, the HCP was modified with highly dispersed ultrafine Pd nanoparticles (Pd/HCP). The obtained Pd/HCP shows excellent catalytic activity in the catalytic reduction of nitroarenes under mild reaction conditions. It′s worth mentioning that the N atoms in the HCP can efficiently coordinate Pd ions to form small Pd nanoparticles (NPs) and subsequently prevent the aggregation and leaching of Pd NPs during the reaction, so the Pd/HCP catalyst is highly stable and can be reused at least eight cycles without loss of catalytic activity. Therefore, this work may provide possibilities for using HCPs as ideal supporting materials for fabricating highly stable and efficient heterogeneous catalysts.
- Xu, Dan,Wang, Fushan,Yu, Guiqin,Zhao, Hong,Yang, Jing,Yuan, Man,Zhang, Xiaoyun,Dong, Zhengping
-
p. 4569 - 4577
(2018/09/11)
-
- Synthesis of 2, 6 - diamino-toluene
-
The invention relates to a method for synthesizing 2, 6-diaminotoluene. The method comprises the following step: by using 2-chlorine-6-nitrotoluene as a raw material, carrying out reduction reaction and ammonolysis reaction to obtain 2, 6-diaminotoluene. The process is simple in synthesis route, easy to control the reaction and few in three wastes generated at the working segments, thereby meeting the green and environmental friendly requirements; and moreover, produced 2, 6-diaminotoluene is high in purity and excellent in quality, so that the method is an excellent industrial route.
- -
-
Paragraph 0028
(2017/01/31)
-
- A 2, 6 - diamino toluene preparation method (by machine translation)
-
The present invention relates to intermediates in the synthesis of fine with the field, in particular to a catalyzing ammoniation preparation 2, 6 - diamino-toluene. The method comprises the following steps: to absolute ethanol as the solvent, 2, 6 - dichloro toluene as the starting material, the ammonia is the aminating agent, under the action of the palladium complex catalyst, atmospheric heating and stirring, to obtain 2, 6 - diamino-toluene. The synthesis method to avoid in the traditional technique of high temperature and high pressure conditions; the economic cost is reduced, and is simple, the reaction process is simple; at the same time environmental protection, prevent a large amount of used raw material harmful to the environment. (by machine translation)
- -
-
Paragraph 0010; 0021
(2017/02/17)
-
- Visible-Light-Assisted Photocatalytic Reduction of Nitroaromatics by Recyclable Ni(II)-Porphyrin Metal-Organic Framework (MOF) at RT
-
A microporous Ni(II)-porphyrin metal-organic framework (MOF), [Ni3(Ni-HTCPP)2(μ2-H2O)2(H2O)4(DMF)2]·2DMF, (MOF1) (where, Ni-HTCPP = 5,10,15,20-tetrakis(4-benzoate) porphyrinato-Ni(II)) has been synthesized by the solvothermal route. Single-crystal X-ray diffraction study of 1 reveals a 2D network structure constituted by Ni3 cluster and [Ni-HTCPP]3- metalloligand having (3, 6)-connected binodal net with {43}2{46·66·83}-kgd net topology. The 2D layers are further stacked together through π-π interactions between the porphyrin linkers to generate a 3D supramolecular framework which houses 1D channels with dimension of ~5.0 × 9.0 ?2 running along the crystallographic a-axis. Visible-light-assisted photocatalytic investigation of MOF1 for heterogeneous reduction of various nitroaromatics at room temperature resulted in the corresponding amines with high yield and selectivity. On the contrary, the Ni(II)-centered porphyrin tetracarboxylic acid [Ni-H4TCPP] metalloligand does not show the photocatalytic activity under similar conditions. The remarkably high catalytic performance of MOF1 over [Ni-H4TCPP] metalloligand has been attributed due to cooperative catalysis involving the Ni-centered porphyrin secendary building units (SBUs) and the Ni3-oxo node. Further, the MOF1 was recycled and reused up to three cycles without any significant loss of catalytic activity as well as structural rigidity. To the best of our knowledge, MOF1 represents the first example of MOF based on 3d metal ion exhibiting visible-light-assisted reduction of nitroaromatics under mild conditions without the assistance of noble metal cocatalysts.
- Deenadayalan,Sharma, Nayuesh,Verma, Praveen Kumar,Nagaraja
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p. 5320 - 5327
(2016/06/14)
-
- Efficient chemoselective reduction of nitro compounds and olefins using Pd-Pt bimetallic nanoparticles on functionalized multi-wall-carbon nanotubes
-
We report the synthesis of novel Pd-Pt bimetallic nanoparticle catalysts using functionalized multi-wall carbon-nanotubes and utilization of them to reductions. The carbon nanotube-supported bimetallic nanoparticle catalysts showed improved activity in reduction reactions, compared with that of mono metal-supported catalysts. Under the optimized reaction conditions, various nitro compounds and alkenes were cleanly reduced at ambient temperature. Furthermore, this catalytic system exhibits excellent activity and high chemoselectivity for nitro compounds in the presence of other functional groups labile to hydrogenation. After the reaction, the catalysts could be collected through filtration, and reused for 10 times without any loss of catalytic activity.
- Kim, Eunsuk,Jeong, Han Saem,Kim, B. Moon
-
-
- One pot catalytic NO2 reduction, ring hydrogenation, and N-alkylation from nitroarenes to generate alicyclic amines using Ru/C-NaNO 2
-
A report to produce alicyclic amines and subsequent N-alkylation with alcohols using Ru/C-NaNO2 catalyzed facile transformation of nitrobenzene was investigated. Effects of solvent, temperature, pressure, reaction time, and molar-ratio of substrate/catalyst on product composition were also studied. These mechanistic studies explain that nitrobenzene undergoes hydrogenation reaction in the following order; -NO2 reduction to -NH2, aromatic ring-hydrogenation to alicyclic, and from the reaction of alcohol to give N-alkylated amines. This investigation shed lights on possible application to polyurethane chemistry since these amines are used as important precursors for diisocyanates.
- Oh, Seung Geun,Mishra, Vivek,Cho, Jin Ku,Kim, Baek-Jin,Kim, Hoon Sik,Suh, Young-Woong,Lee, Hyunjoo,Park, Ho Seok,Kim, Yong Jin
-
-
- PROCESS FOR PREPARING TOLUENEDIAMINE BY HYDROGENATION OF DINITROTOLUENE
-
The invention relates to a process for the continuous preparation of toluenediamine by liquid-phase hydrogenation of dinitrotoluene by means of hydrogen in the presence of a suspended, nickel-comprising catalyst in a reactor with a product isolation unit downstream of the reactor to give a product output from the reactor comprising a liquid phase comprising toluenediamine and dinitrotoluene, in which the nickel-comprising catalyst is suspended, wherein the concentration of dinitrotoluene in the liquid phase of the product output from the reactor in the region between the reactor and the downstream product isolation unit is set to a value in the range from 1 to 200 ppm by weight, based on the total weight of the liquid phase of the product output from the reactor.
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-
Page/Page column 4-5
(2011/12/13)
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- Simple one-pot synthesis of Rh-Fe3O4 heterodimer nanocrystals and their applications to a magnetically recyclable catalyst for efficient and selective reduction of nitroarenes and alkenes
-
A simple synthesis of Rh-Fe3O4 heterodimer nanocrystals was achieved by controlled one-pot thermolysis. The nanocrystals exhibited excellent activities for the selective reduction of nitroarenes and alkenes. Furthermore the nanocrystal catalyst could be easily separated by a magnet, and recycled eight times without losing the catalytic activity.
- Jang, Youngjin,Kim, Seyoung,Jun, Samuel Woojoo,Kim, Byung Hyo,Hwang, Sunhwan,Song, In Kyu,Kim, B. Moon,Hyeon, Taeghwan
-
supporting information; experimental part
p. 3601 - 3603
(2011/04/26)
-
- A novel iodide-catalyzed reduction of nitroarenes and aryl ketones with H3PO2 or H3PO3: Its application to the synthesis of a potential anticancer agent
-
A novel iodide-catalyzed reduction method using hypophosphorous and/or phosphorus acids was developed to reduce both diaryl ketones and nitroarenes chemoselectively in the presence of chloro and bromo substituents in high yield. This efficient and practical method has been successfully applied to a large scale production of a potential anticancer agent
- Wu, George G.,Chen, Frank X.,LaFrance, Danny,Liu, Zhijian,Greene, Scott G.,Wong, Yee-Shing,Xie, Ji
-
supporting information; experimental part
p. 5220 - 5223
(2011/12/04)
-
- Fe3O4 nanoparticles: A conveniently reusable catalyst for the reduction of nitroarenes using hydrazine hydrate
-
A magnetic personality: Commercially available Fe3O4 nanoparticles were utilized for efficient nitroarene reductions, and could be recycled up to 10 times using magnetic separation, whilst retaining activity (99 % aniline yield in each case without any side-products). Excellent chemoselectivity for reduction of the nitro versus other functional groups, such as halogen, ester, O-benzyl, and N-Cbz groups, was observed.
- Kim, Seyoung,Kim, Eunsuk,Kim, B. Moon
-
experimental part
p. 1921 - 1925
(2011/10/17)
-
- Process for the production of the toluene diisocyanate
-
The invention relates to a process for the production of toluene diisocyanate, in which the crude toluenediamine obtained from the hydrogenation is purified and then phosgenated. The purification step reduces the total amount of cyclic ketones to less than 0.1 % by weight, based on 100% by weight of the toluenediamine.
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-
Page/Page column 5; 6
(2008/06/13)
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- Bis-Amination of Aryl Halides
-
Disclosed are methods for making 1,3- and 1,4-diamino-phenyl intermediates by utilizing bis-amination of ortho-substituted aryl halides.
- -
-
Page/Page column 3
(2008/06/13)
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- N-cyanoethylated ortho and meta toluenediamine compounds
-
The invention provides N-cyanoethylated toluenediamines (CNTDAs), processes for synthesizing them, and compositions containing them. In preferred embodiments, the CNTDAs are represented by the following formula: where the nitrogen atoms are ortho or meta to each other on the aromatic ring. The CNTDAs are particularly suitable for use as latent curing agents for epoxy resins.
- -
-
-
- N-(Aminopropyl)-toluenediamines and their use as epoxy curing agents
-
The invention provides N-aminopropylated toluenediamines, processes for synthesizing them, compositions containing them and methods for using them to cure epoxy resins. In preferred embodiments, the N-aminopropylated toluenediamines are represented by the following formula: where the nitrogen atoms are ortho or meta to each other on the aromatic ring.
- -
-
-
- Method for producing amines
-
The invention relates to a process for the preparation of amines by hydrogenation of nitro compounds, which comprises carrying out the hydrogenation in a vertical reactor whose length is greater than its diameter, having a downward-facing jet nozzle arranged in the upper region of the reactor through which the starting materials and the reaction mixture are fed in, and having an outlet at any desired point of the reactor, through which the reaction mixture is fed back to the jet nozzle in an external circuit by means of a conveying means, and having flow reversal in the lower region of the reactor.
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-
Page column 7-8
(2008/06/13)
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- Raney nickel catalysts, a method for producing said raney nickel catalysts and the use of the same for hydrogenating organic compounds
-
Raney nickel catalysts obtainable by a process in which the melt of an alloy comprising 50 to 94 wt. % aluminum, 10 to 50 wt. % nickel, 0 to 20 wt. % iron, 0 to 15 wt. % cerium, cerium mixed metal, vanadium, niobium, tantalum, chromium, molybdenum or manganese and, optionally, further glass-forming elements is allowed to solidify rapidly with a cooling rate of >104K/s and the rapidly solidified alloy is then subjected to a treatment with organic or inorganic bases are described. A process for the preparation of the Raney nickel catalysts mentioned and their use in the hydrogenation of organic compounds, in particular aromatic nitro compounds, are furthermore described.
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Page column 5-6
(2008/06/13)
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- Process for separating mixtures of materials having different boiling points
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A mixture of materials having different boiling points is separated into fractions having different boiling points. The separated fraction containing the desired product is stripped using the vapors of a lower boiling fraction. The process of the present invention is particularly useful for recovering a desired isomer or isomer mixture from a technical mixture obtained during production of an aromatic amine such as toluenediamine. Little or no unwanted isomer or by-product is present in the isomer or isomer mixture product of this process.
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-
Page column 7
(2008/06/13)
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- N-(aminopropyl)-toluenediamines and their use as epoxy curing agents
-
The invention provides N-aminopropylated toluenediamines, processes for synthesizing them, compositions containing them and methods for using them to cure epoxy resins. In preferred embodiments, the N-aminopropylated toluenediamines are represented by the following formula: where the nitrogen atoms are ortho or meta to each other on the aromatic ring.
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-
-
- Electrochemical treatment of 2,4,6-trinitrotoluene and related compounds
-
This work involves electrolysis of nitrotoluene congeners, which are persistent pollutants that enter the environment as a consequence of their manufacture and use as explosives. Reduction to aminotoluenes occurred with high current efficiency at a variety of cathodes, at potentials -0.5 to -1 V vs SCE. The products were formed in high chemical yield and with excellent mass balance. Preliminary experiments were also carried out to find methods of removing the electrolysis products from solution by oxidative oligomerization. The most satisfactory method was partial reoxidation at a Ti/IrO2 anode, suggesting an overall remediation technology in which reduction is followed by reoxidation of the spent catholyte in the anode compartment of the same electrolytic cell. This work involves electrolysis of nitrotoluene congeners, which are persistent pollutants that enter the environment as a consequence of their manufacture and use as explosives. Reduction to aminotoluenes occurred with high current efficiency at a variety of cathodes, at potentials -0.5 to -1 V vs SCE. The products were formed in high chemical yield and with excellent mass balance. Preliminary experiments were also carried out to find methods of removing the electrolysis products from solution by oxidative oligomerization. The most satisfactory method was partial reoxidation at a Ti/IrO2 anode, suggesting an overall remediation technology in which reduction is followed by reoxidation of the spent catholyte in the anode compartment of the same electrolytic cell.
- Rodgers, James D.,Bunce, Nigel J.
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p. 406 - 410
(2007/10/03)
-
- Indium metal as a reducing agent in organic synthesis
-
The low first ionisation potential (5.8 eV) of indium coupled with its stability towards air and water, suggest that this metallic element should be a useful reducing agent for organic substrates. The use of indium metal for the reduction of C=N bonds in imines, the heterocyclic ring in benzo-fused nitrogen heterocycles, of oximes, nitro compounds and conjugated alkenes and the removal of 4-nitrobenzyl protecting groups is described. Thus the heterocyclic ring in quinolines, isoquinolines and quinoxalines is selectively reduced using indium metal in aqueous ethanolic ammonium chloride. Treatment of a range of aromatic nitro compounds under similar conditions results in selective reduction of the nitro groups; ester, nitrile, amide and halide substituents are unaffected. Likewise indium in aqueous ethanolic ammonium chloride is an effective method for the deprotection of 4-nitrobenzyl ethers and esters. Indium is also an effective reducing agent under non-aqueous conditions and α-oximino carbonyl compounds can be selectively reduced to the corresponding N-protected amine with indium powder, acetic acid in THF in the presence of acetic anhydride or di-tert-butyl dicarbonate. Conjugated alkenes are also reduced by indium in THF-acetic acid.
- Pitts,Harrison,Moody
-
p. 955 - 977
(2007/10/03)
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- Chemical behaviour of seven aromatic diisocyanates (toluenediisocyanates and diphenylmethanediisocyanates) under in vitro conditions in relationship to their results in the Salmonella/microsome test
-
There are conflicting results on the mutagenicity of toluenediisocyanate (TDI) and diphenylmethanediisocyanate (MDI). It was found that the organic solvent chosen to dissolve the compounds dictates the outcome of the bacterial tests. The Salmonella/microsome tests showed uniformly mutagenic effects for all the compounds that were predissolved in DMSO. Due to the instability of aromatic diisocyanates in DMSO this solvent was replaced by ethyleneglycoldimethylether (EGDE). TDI and MDI endured the dissolving and were therefore still available for the subsequent bacterial tests. Furthermore, no aromatic diamines (TDA or MDA) could be detected in EGDE prior to the start of the assays. The Salmonella/microsome tests, however, revealed unexpected differences between TDI and MDI. As previously published the four types of MDI showed negative results, whereas the data presented in this paper demonstrated mutagenic effects of all three types of TDI if EGDE is the solvent. To gain deeper insight into the chemical changes that occurred during the Salmonella/microsome test, the possible reactions were modelled in the laboratory by mixing predissolved diisocyanates with a defined surplus of water and monitoring the progress of the chemical reactions by analytical methods. Additionally, the quality of the model was checked by exposing solutions of 2,6-TDI and 4,4'-MDI to the real biological test environment. In both cases, the reaction patterns of TDI were different to those of MDI. Within 1 min, which is the maximum time needed to mix the predissolved compounds with water before they are poured onto the agar plate, the TDI content was reduced in favour of different ureas and TDA. In addition water was replaced by the complete set of test ingredients. While the TDA content remained more or less constant, the amount of residual TDI was reduced considerably. Reactions of MDI were markedly slower than those of TDI. More than 90% of the predissolved MDI remained intact when it was mixed with water. The biological test ingredients accelerated the reduction of the MDI content. Within 45 s, more than two thirds of the MDI disappeared. Evidently, the chemical reactions continue during incubation. It is assumed that the contrasting results of TDI and MDI in the Salmonella/microsome test are due to the different reaction patterns-and reaction products-of the predissolved diisocyanates created under the specific conditions of the test. These findings indicate that the chemical interactions between reactive test compounds and solvents or test media need to be considered in the interpretation of the relevance of test results. Copyright (C) 1999 Elsevier Science B.V.
- Seel,Walber,Herbold,Kopp
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p. 109 - 123
(2007/10/03)
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- Formation, solvolysis, and transcarbamoylation reactions of bis(S- glutathionyl) adducts of 2,4- and 2,6-diisocyanatotoluene
-
During our ongoing studies of the reactions of toluene diisocyanate (2,4- and 2,6-diisocyanatotoluene, TDI) in vivo, it became apparent that reactive form(s) of these diisocyanates reach(es) the circulatory system after passage through the respiratory system. Based on recent work by others regarding the transcarbamoylation reactions of monoisocyanates, we hypothesized that the reactive form could be masked as an S- thiocarbamoylglutathione adduct of one or more of the isocyanato moieties. In this study, the glutathione adducts of 2,4- and 2,6-diisocyanatotoluene were synthesized under physiological conditions. Bis adducts were the major products when near-equimolar amounts of glutathione and the individual diisocyanato compounds were mixed at physiological pH, and were formed in high yield. Little to no mono adducts formed under these reaction conditions. The masses of the bis adducts were confirmed by electrospray mass spectrometry (MS), and 1H NMR analysis strongly suggested that the thiol of the cysteine residue of glutathione was the nucleophile in each case. The rates of solvolysis of the two bis adducts in aqueous buffer under conditions of physiological temperature and pH were determined, and electrospray MS analysis showed that the corresponding mono(glutathionyl)-TDIs were formed in these reactions. Incubation in vitro of each of the bis(glutathionyl)-TDI adducts with a 12 amino acid peptide (Thr-Cys-Val-Glu-Trp-Leu-Arg-Arg-Tyr- Leu-Lys-Asn) at pH 7.5 resulted in transfer of one mono(glutathionyl)- toluylisocyanato moiety to the peptide as detected by HPLC and on-line electrospray MS analyses. In both the solvolysis and transfer experiments, the 2,4-TDI-derived bis(glutathionyl) adduct reacted most quickly, while both the bis(glutathionyl)-2,6-TDI adduct and its transfer product with the peptide were more stable than their 2,4-TDI-derived counterparts. The results indicate high stoichiometry in formation and ready transfer to nucleophilic sites of protein, and suggest that the isocyanato moiety of both 2,4- and 2,6-TDI may be regenerated in vivo from their bis(glutathionyl) adducts. As a consequence, the thiol status of particular tissues may be a contributing factor to individual TDI toxicity susceptibility, and a mechanism by which toxicity at sites distant to the initial point of contact may be proposed.
- Day, Billy W.,Jin, Ruhzi,Basalyga, Dina M.,Kramarik, Jean A.,Karol, Meryl H.
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p. 424 - 431
(2007/10/03)
-
- Preparation of n-aryl amines from isocyanates
-
Methods of producing N-phenyl amines comprise reacting a phenyl-containing isocyanate with HR, and a boron complexing agent in an aprotic solvent, wherein R, is --OH or --COOH (i.e., water or formic acid), neutralizing the resulting N-aryl amide to N-aryl amine and recovering the N-aryl amine.
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-
- Synthesis of phthalonitrile resins containing ether and imide linkages
-
Imide-containing phthalonitrile monomers are prepared from a phthalonitrile and an aromatic dianhydride. The monomer and a method for preparing the monomer is disclosed. These monomers are synthesized into heat resistant polymers and copolymers with aromatic ring structure incorporating imide and ether linkages. The synthesis of the high temperature thermosetting polymers and copolymers is also disclosed.
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-
- An integrated process for the preparation of aromatic mono- and polyisocyanates from aromatic amines
-
A multi-step process for the preparation of aromatic mono- and polyisocyanates in which an aromatic mono- or polyamine and isocyanic acid are reacted to form an aromatic urea which is then reacted with a dialkyl amine to give an aromatic dialkyl urea product. The aromatic dialkyl urea is thermally treated in an inert organic solvent in the presence of a reaction promoter to produce the isocyanate.
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-
-
- Process for the preparation of optionally p-chlorine-substituted 2,6-diaminotoluene
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The invention relates to a process for the preparation of optionally p-chlorine-substituted 2,6-diaminotoluene, which is characterized in that 3,4-dichlorotoluene is dinitrated in the presence of an inert, water-immiscible, organic solvent and/or diluent at temperatures of -10° to +100° C. and is subsequently reduced, optionally after intermediate isolation of the dinitro compound, in the presence of an inert organic solvent and/or diluent and/or of water, with partial or complete splitting-off of the chlorine atoms, to give the diamino compound. 2,6-Diaminotoluenes are valuable intermediates for the preparation of diisocyanates and polyurethanes; the 2,6-diaminotoluene is furthermore used for the preparation of dyestuffs and antioxidants.
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- Azo reactive dyestuffs having an aryl-triazinyl-aryl diazo component
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Optionally metallized azo dyestuffs which in the form of the free acid correspond to the formula STR1 wherein K is the radical of a benzene, naphthalene, pyrazolone, pyridone, pyrimidone, acetoacetic acid arylide or aminopyrazole coupling component; A is a non-ionic substituent; X is STR2 wherein W is a direct bond or a bridge member to a C atom of the benzene or naphthalene nucleus or the coupling component K; R is hydrogen or C1 -C4 -alkyl; B is a direct bond or a bridge member, especially -CO- or -SO2 -, to a C atom of Q; Q is a reactive radical; m is 0, 1 or 2; n is 0, 1 or 2; p is 0 or 1; q is 0, 1 or 2; and r is 0 or 1; and their use for the dyeing and printing of natural and regenerated cellulose fibre materials such as cotton and rayon, as well as natural and synthetic polyamide fibre materials, for example those of wool, silk, poly-ε-caprolactam or polycondensate of hexamethylene-diamine and adipic acid. The dyeings obtained, espeically those on cotton and rayon, are distinguished by good fastness properties, especially fastness to wet processing and to light.
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- Preparation of a chlorinated diisocyanate
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A process for the preparation of compounds represented by the formula SPC1 Wherein Z is EQU1 WHEREIN R' and R' are hydrogen, alkyl or aryl and n is 0 or a positive integer, which compounds are particularly useful as chain extenders or in preparing isocyanates or polyols to be used in the production of polyurethane plastics.
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