1208-52-2Relevant academic research and scientific papers
HETEROGENEOUS SYNTHESIS OF METHYLENE DIANILINE
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Page/Page column 28-32, (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.
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.
METHOD OF PRODUCING DIAMINES AND POLYAMINES OF THE DIPHENYLMETHANE SERIES
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Paragraph 0134-0140; 0152-0159, (2020/03/28)
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 isomer composition in the resulting diamines of the diphenylmethane series (altering the 2,4′-MDA content). Adapting the molar ratios of the total used aniline to the total used formaldehyde and of the total used acid catalyst to the total used aniline, 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.
Synthetic method of 2-(4-aminobenzyl) aniline
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Paragraph 0051-0053, (2018/05/16)
The invention discloses a synthetic method of 2-(4-aminobenzyl) aniline. The method comprises the following steps: carrying out Suzuki coupling reaction on 2-aminophenylboronic acid (1) and nitrobenzyl bromide (2) in a mixed solvent of water and an organic solvent to generate 2-(4-nitrobenzyl) aniline (3); dissolving the 2-(4-nitrobenzyl) aniline (3) obtained in the previous step into methanol, and carrying out catalytic hydrogenation in the hydrogen atmosphere to obtain 2-(4-aminobenzyl) aniline (4). According to the synthetic method disclosed by the invention, the problems of generation of aplurality of isomers and complex separation in the prior art are solved; the synthetic method has the advantages of mild reaction conditions of a path, simple purification conditions and suitabilityfor enlarged production; a final product is prepared at higher yield and high purity.
For the preparation of diamino diphenyl alkane method
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Paragraph 0056-0060, (2017/03/17)
The invention relates to a method for producing diaminodiphenyl alkanes, wherein an aromatic amine, which can be substituted or unsubstituted, is reacted with a C1-C3 aldehyde in the presence of a heterogeneous catalyst, said catalyst being a mesoporous acidic ion exchanger based on a divinylbenzene/styrene copolymer and the catalyst having acid centers in a concentration of 2 to 6 eq/kg measured according to DIN 54403 and the average pore diameter of the catalyst particles being 10 to 32 nm measured according to ASTM D 4222, and the content of polynuclear compounds in the reaction mixture being >10 and ?15% by weight.
Efficient Sc triflate mesoporous-based catalysts for the synthesis of 4,4′-methylenedianiline from aniline and 4-aminobenzylalcohol
Candu, Natalia,Ciobanu, Madalina,Filip, Petru,Haskouri, Jamal El,Guillem, Carmen,Amoros, Pedro,Beltran, Daniel,Coman, Simona M.,Parvulescu, Vasile I.
scheme or table, p. 76 - 85 (2012/03/27)
Sc triflate mesoporous-based catalysts have been prepared using a two-step strategy (i.e., Atrane method) based on the formation of the hierarchic bimodal porosity in the first step and the formation of Sc triflate complexes at the materials surface in the second step. All solids were analyzed by EPMA, surface area, and pore size values, XRD, TEM, FTIR, and 45Sc NMR static spectra. The catalysts have been investigated in the synthesis of 4,4′-methylenedianiline (4,4′-MDA) from aniline and 4-aminobenzylalcohol. 4,4′-MDA was obtained with selectivities over 85.0% for a conversion of aniline of 31%, at 80 °C and after 24 h. Using microwaves, selectivities of 90% in 4,4′-MDA were reached in only 3 h. Important key parameters influencing the catalytic performances seem to be the scandium content and the nature of the formed Sc species. By replacing formaldehyde with 4-aminobenzylalcohol, the necessity of additional steps for neutralization and separation of the wastes can be eliminated.
Reaction network and mechanism of the synthesis of methylenedianiline over dealuminated Y-type zeolites
Salzinger, Michael,Lercher, Johannes A.
experimental part, p. 149 - 155 (2011/03/22)
The reaction network and mechanism of the synthesis of methylenedianiline (MDA) from the condensation product of aniline and formaldehyde (aminal) on microporous acidic materials has been elucidated. The first step of the reaction, the decomposition of the aminal to N-benzylanilines, is limited by film diffusion, and the second and significantly slower step, the acid catalyzed rearrangement of these intermediates to MDA, is controlled by microkinetics on mesoporous dealuminated Y-type zeolites. This second step of the reaction network is limited by pore diffusion on zeolite BEA as an example for non-mesoporous materials. Based on time-concentration profiles, we were able to determine the reaction orders of the initial decomposition of the aminal to one and two for the following rearrangement of para-aminobenylaniline to 4,4′-MDA. From the kinetic data we deduced an SN2-type reaction mechanism and a complex reaction network, which is able to simulate the observed concentration profiles. The aniline to formaldehyde ratio in the starting mixture had a negligible influence on the final product distribution.
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.
LOW CHLORINE, MULTI-STAGED METHOD FOR PRODUCING CYCLOALIPHATIC DISOCYANATES
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Page/Page column 14, (2011/02/25)
Low chlorine, multi-staged method for producing cycloaliphatic diisocyanates. The invention relates to a multi-staged method for the continuous low-chlorine production of cycloaliphatic diisocyanates, comprising the synthesis of diaminodipheynl alkanes, the hydration thereof into the corresponding cycloaliphatic diamines and the subsequent conversion of cycloaliphatic diamines to the corresponding cycloalkylene biscarbamates and the thermal cleaving of the latter into the cycloaliphatic diisocyanates and alcohol.
Method of preparing polymethylene-polyphenyl-polyamine
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Page/Page column 8-9; 11, (2011/04/13)
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 exchanger 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.
