1758-73-2Relevant academic research and scientific papers
Lewis acid solid catalysts for the synthesis of methylenedianiline from aniline and formaldehyde
Cheung, Ka Yan,De Baerdemaeker, Trees,De Vos, Dirk,Gordillo, Alvaro,Marquez, Carlos,Parvulescu, Andrei-Nicolae,Tomkins, Patrick
, p. 114 - 123 (2021/06/16)
A catalyst containing Hf4+ and Zn2+ supported on silica has been found to be highly effective for the synthesis of methylenedianiline (MDA), an indispensable precursor in the polyurethane industry. Its performance was further improved when the silica support was replaced by silica-alumina, which resulted in a catalyst that was both active and selective, as indicated by the high MDA yield and high 4,4′–MDA/(2,2′–MDA + 2,4′–MDA) isomer ratio obtained. Furthermore, the catalyst also gave an appreciable oligomeric MDA (OMDA) yield and was noticeably more stable than the zeolites that were used in comparative tests: it could be used in at least five consecutive runs without any significant loss in activity. The combination of Br?nsted and Lewis acidity strongly increases the overall activity and yields a catalyst that represents a remarkably stable and reusable alternative to the commonly studied systems for this reaction.
HETEROGENEOUS SYNTHESIS OF METHYLENE DIANILINE
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Page/Page column 33-35, (2021/06/22)
The present invention relates to a catalytic material for the preparation of one or more of 4,4'- methylenedianiline, 2,2'-methylenedianiline, 2,4'-methylenedianiline, and oligomers of two or more thereof, the catalytic material comprising an oxidic support, wherein the oxidic support comprises an element EOS1 selected from the group consisting of Ti, Zr, Al, Si, and mixtures of two or more thereof, and further comprising a supported material supported on the oxidic support, wherein the supported material comprises an element ESM1 selected from the group consisting of Ti, Zr, V, Nb, Ta, Mo, W, Ge, Sn, Sc, Y, La, Ce, Nd, Pr, Hf, Cr, Fe, Co, Ni, Cu, Zn, Pb, and mixtures of two or more thereof. Further, the present invention relates in particular to a process for the preparation of a catalytic material and to a process for the preparation of one or more of 4,4'-methylenedianiline, 2,2'-methylenedianiline, 2,4'-methylenedianiline and oligomers of two or more thereof.
Electrooxidation of Formamidine Disulfide Simultaneously Investigated by On-Line High Performance Liquid Chromatography and Cyclic Voltammetry
Feng, Na,Li, Fengli,Liu, Yang,Luo, Hainan,Zhang, Baoying,Zhang, Wei,Zhao, Yuyan
, p. 1074 - 1080 (2021/11/03)
The electro-oxidation of formamidine disulfide, an important sulfur-containing compound, was simultaneously investigated with on-line high-performance liquid chromatography and cyclic voltammetry. Using a home-made microporous sampler located at the electrode interface, the solution on the electrode surface was in situ sampled and analyzed. The electrochemical scanning was synchronously performed, which allowed the electro-oxidation products to be detected at a given potential. The main products on the surface of platinum electrode were found to be thiourea, formamidine sulfinic acid, cyanamide, and elemental sulfur. Forced convection arising from the sampling played an important role in the electrochemical oxidation. The extraction of electrode surface solution promoted the renewal of reactant and its intermediates, which induced the change of cyclic voltammetry curve. The forced convection also contributed to the redox peak current of the species on the cyclic voltammetry curves through the change of concentration of reactant and its intermediates. This technique can help to explore the reaction mechanism of complex electrochemical reactions.
METHOD OF PRODUCING DIAMINES AND POLYAMINES OF THE DIPHENYLMETHANE SERIES
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Paragraph 0136-0167, (2020/05/02)
The invention relates to a method for producing diamines and polyamines of the diphenylmethane series, by condensing aniline and formaldehyde followed by an acid-catalysed rearrangement at different production capacities with alteration of the content of diamines of the diphenylmethane series (altering the binuclear content). Adapting the molar ratio of the total used aniline to the total used formaldehyde and adapting the reaction temperature allows the rearrangement reaction to be fully completed despite the change in dwell time inevitably associated with a change in production capacity, and allows the formation of undesired by-products to be avoided as far as possible; the intended modification to binuclear content is likewise achieved.
Selective oxidation of thiourea with H2O2 catalyzed by [RuIII(edta)(H2O)]-: Kinetic and mechanistic studies
Chatterjee, Debabrata,Rothbart, Sabine,Van Eldik, Rudi
, p. 4725 - 4729 (2013/05/09)
Reported here is the first example of a ruthenium complex, [Ru III(edta)(H2O)]- (edta4- = ethylenediaminetetraacetate), that catalyzes the oxidation of thiourea (TU) in the presence of H2O2. The kinetics and mechanism of this reaction were investigated in detail by using rapid-scan spectrophotometry as a function of both the hydrogen peroxide and thiourea concentrations at pH 4.9 and 25 °C. Spectral analyses and kinetic data clearly support a catalytic process in which hydrogen peroxide reacts directly with thiourea coordinated to the RuIII(edta) complex. HPLC product analyses revealed the formation of formamidine disulfide (TU2) as a major product at the end of the catalytic process, however, formation of other products like thiourea dioxide (TUO2), thiourea dioxide (TUO3) and sulfate was also observed after longer reaction times. Catalytic intermediates such as [Ru III(edta)(OOH)]2- and [RuV(edta)(O)] - were evidently found to be non-reactive in catalyzing the oxidation of thiourea by H2O2 under the specified conditions. The Royal Society of Chemistry 2013.
Oxyhalogen-sulfur chemistry: Oxidation of a thiourea dimer, formamidine disulfide, by chlorine dioxide
Martincigh, Bice S.,Mhike, Morgen,Morakinyo, Kayode,Adigun, Risikat Ajibola,Simoyi, Reuben H.
, p. 362 - 369 (2013/05/09)
The oxidation of formamidine disulfide, FDS, the dimer of thiourea, by aqueous chlorine dioxide has been studied in highly acidic and mildly acidic media. FDS is one of the possible oxidation intermediates formed in the oxidation of thiourea by oxyhalogens to urea and sulfate. The reaction is exceedingly slow, giving urea and sulfate with a stoichiometric ratio of 5:14 FDS to chlorine dioxide after an incubation period of up to 72h and only in highly acidic media which discourages the disproportionation of chlorine dioxide to the oxidatively inert chlorate. Mass spectrometric data suggest that the oxidative pathway proceeds predominantly through the sulfinic acid, proceeding next to the products sulfate and urea, while by-passing the sulfonic acid. Transient formation of the unstable sulfenic acid was also not observed.
Kinetic study on hydrolysis and oxidation of formamidine disulfide in acidic solutions
Hu, Ying,Feng, Jiamin,Li, Yanwei,Sun, Yanyan,Xu, Li,Zhao, Yuemin,Gao, Qingyu
experimental part, p. 235 - 241 (2012/03/22)
Hydrolysis and oxidation of formamidine disulfide in acidic medium were investigated using high-performance liquid chromatography (HPLC) and mass spectrometry (MS) at 25 °C. By controlling the slow reaction rate and choosing appropriate mobile phase, HPLC provides the unique advantages over other methods (UV-Vis, chemical separation) in species tracking and kinetic study. In addition to thiourea and formamidine sulfinic acid, two unreported products were also detected in the hydrolysis reaction. Mass spectrometry measurement indicates these two products to be formamidine sulfenic acid and thiocyanogen with mass weights of 92.28 and 116.36, respectively. In the oxidation of formamidine disulfide by hydrogen peroxide, besides thiourea, formamidine sulfenic acid, formamidine sulfinic acid, thiocyanogen and urea, formamidine sulfonic acid and sulfate could be detected. The oxidation reaction was found to be first order in both formamidine disulfide and hydrogen peroxide. The rate constants of hydrolysis and oxidation reactions were determined in the pH range of 1.5-3.0. It was found both rate constants are increased with the increasing of pH. Experimental curves of different species can be effectively simulated via a mechanism scheme for formamidine disulfide oxidation, including hydrolysis equilibrium of formamidine disulfide and irreversible hydrolysis of formamidine sulfenic acid.
Towards an industrial synthesis of diamino diphenyl methane (DADPM) using novel delaminated materials: A breakthrough step in the production of isocyanates for polyurethanes
Botella,Corma,Carr, Robert H.,Mitchell, Christopher J.
experimental part, p. 143 - 149 (2012/02/13)
Delaminated materials ITQ-2, ITQ-6 and ITQ-18 are very efficient catalysts of zeolitic nature for the synthesis of diamino diphenyl methane (DADPM), the polyamine precursor in the production of MDI for polyurethanes. The exfoliation process results in excellent accessibility of their active sites to reactant molecules as well as fast desorption of products. These catalysts present higher activity and slower rates of deactivation than their corresponding zeolites. Moreover, the topology of the delaminated structure imposes a precise control of the isomer distribution, offering an additional flexibility in the synthesis of DADPM. By optimizing the process conditions it is possible to achieve final DADPM crude under industrial production specifications with ITQ-18. This catalyst represents a real chance for replacing HCl in the industrial production of DADPM.
A PROCESS FOR PREPARATION OF POLYMETHYLENE POLYPHENYL POLYAMINE
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Page/Page column 6, (2010/02/17)
The present invention provides a method of preparing polymethylene-polyphenyl-polyamine (briefly referred to as polyamine, DAM), in which a high gravity rotating bed is used as the mixing reactor of formaldehyde and aniline hydrochloride, the mixing solution of aniline hydrochloride and circulation solution and the formaldehyde are fed into the high gravity rotating bed reactor proportionally to carry out mixing and condensation reaction under a condition of a very high gravity; the materials leaving the high gravity rotating bed reactor is introduced into a stirred vessel to proceed with the pre-condensation reaction and obtain a condensation solution; and the process steps of heating, molecular rearrangement, neutralization, water washing and purification, etc. are completed to obtain the refined DAM. With the method according to the present invention, the main by-products is obviously reduced in the condensation process, the phenomenon of deposit attaching to the inner walls of circulation pipes and heat exchange and blockage are prevented in the condensation process, the impurity content is low in the refined DAM, and the subsequent product MDI has a lighter color, the product quality is stable and may be improved to a certain extent.
PROCESS FOR PRODUCING DIAMINES AND POLYAMINES OF THE DIPHENYLMETHANE SERIES
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Page/Page column 6, (2009/10/01)
The present invention relates to a process for producing diamines and polyamines of the diphenylmethane series (MDA) by reacting aniline and formaldehyde in the presence of an acid catalyst, wherein the aniline contains in total less than 0.5 wt. %, based on the total weight of aniline, of one or more compounds which contain at least one carbonyl group or of one or more compounds that are formed by reaction of these compounds which contain at least one carbonyl group with aniline.
