cas 1758-73-2, Thiourea dioxide | Articles data

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HETEROGENEOUS SYNTHESIS OF METHYLENE DIANILINE
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.
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Page/Page column 33-35

(2021/06/22)

Lewis acid solid catalysts for the synthesis of methylenedianiline from aniline and formaldehyde
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.
Cheung, Ka Yan,De Baerdemaeker, Trees,De Vos, Dirk,Gordillo, Alvaro,Marquez, Carlos,Parvulescu, Andrei-Nicolae,Tomkins, Patrick
p. 114 - 123
(2021/06/16)

Electrooxidation of Formamidine Disulfide Simultaneously Investigated by On-Line High Performance Liquid Chromatography and Cyclic Voltammetry
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.
Feng, Na,Li, Fengli,Liu, Yang,Luo, Hainan,Zhang, Baoying,Zhang, Wei,Zhao, Yuyan
p. 1074 - 1080
(2021/11/03)

METHOD OF PRODUCING DIAMINES AND POLYAMINES OF THE DIPHENYLMETHANE SERIES
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.
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Paragraph 0136-0167

(2020/05/02)

Selective oxidation of thiourea with H2O2 catalyzed by [RuIII(edta)(H2O)]-: Kinetic and mechanistic studies
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.
Chatterjee, Debabrata,Rothbart, Sabine,Van Eldik, Rudi
p. 4725 - 4729
(2013/05/09)

Oxyhalogen-sulfur chemistry: Oxidation of a thiourea dimer, formamidine disulfide, by chlorine dioxide
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.
Martincigh, Bice S.,Mhike, Morgen,Morakinyo, Kayode,Adigun, Risikat Ajibola,Simoyi, Reuben H.
p. 362 - 369
(2013/05/09)

Kinetic study on hydrolysis and oxidation of formamidine disulfide in acidic solutions
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.
Hu, Ying,Feng, Jiamin,Li, Yanwei,Sun, Yanyan,Xu, Li,Zhao, Yuemin,Gao, Qingyu
experimental part
p. 235 - 241
(2012/03/22)

Towards an industrial synthesis of diamino diphenyl methane (DADPM) using novel delaminated materials: A breakthrough step in the production of isocyanates for polyurethanes
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.
Botella,Corma,Carr, Robert H.,Mitchell, Christopher J.
experimental part
p. 143 - 149
(2012/02/13)

A PROCESS FOR PREPARATION OF POLYMETHYLENE POLYPHENYL POLYAMINE
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.
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Page/Page column 6

(2010/02/17)

PROCESS FOR PRODUCING DIAMINES AND POLYAMINES OF THE DIPHENYLMETHANE SERIES
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.
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Page/Page column 6

(2009/10/01)

Process for the production of 4,4'-diphenylmethane diisocyanate
The present invention relates to a process for the production of 4,4′-diphenylmethane diisocyanate (4,4′-MDI) by acid-catalyzed condensation of aniline with formaldehyde, reaction of the mixtures of di- and polyamines obtained with phosgene to form the corresponding mixture of MDI isomers and homologues (di- and polyisocyanates of the diphenylmethane series) and subsequent separation of the mixture by distillation to form 4,4′-MDI and polymeric MDI.
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Page/Page column 3; 4

(2008/06/13)

Process for the production of isocyanates
Isocyanates, preferably diisocyanates and polyisocyanates of the diphenylmethane series (MDI), are produced by reaction of amines dissolved in a solvent with phosgene in the same solvent to form the corresponding isocyanates. Hydrogen chloride and excess phosgene are subsequently removed from the reaction mixture to obtain a crude isocyanate-containing solution. Subsequently, the crude isocyanate-containing solution is separated by distillation into isocyanates and solvent. The solvent is recycled and used for the production of solutions of the amines and of phosgene. The solvent being recycled is treated to reduce the phosgene and diisocyanate contents before being used for the production of the solution of the amine.
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Page/Page column 4

(2008/06/13)

Process for the preparation of 4,4'-diphenylmethane diisocyanate
4,4'-diphenylmethane diisocyanate is produced at two different sites by a) reacting aniline and formaldehyde in the presence of an acid catalyst to produce a mixture of diamines and polyamines of the diphenylmethane series at a first production site, b) these diamines and polyamines are then reacted with phosgene to give the corresponding diisocyanates and polyisocyanates of the diphenylmethane series, which may optionally be separated by distillation to give a mixture of diisocyanates and polyisocyanates containing from 50 to 80 wt.% of 4,4'-diphenylmethane diisocyanate, from 1 to 12 wt.% of 2,4'- and/or 2,2'-diphenylmethane diisocyanate taken together, and from 10 to 45 wt.% of trifunctional and higher-functional polyisocyanates, based on the weight of the mixture of diisocyanates and polyisocyanates, c) transferring the mixture of diisocyanates and polyisocyanates to transport containers and transporting these isocyanate-containing containers to a second production site remote from the first, and d) separating the mixture of diisocyanates and polyisocyanates by distillation and/or crystallization to give a pure 4,4'-diphenylmethane diisocyanate containing at least 97 wt.% of 4,4'-diphenylmethane diisocyanate and a maximum of 3 wt.% of 2,4'-diphenylmethane diisocyanate.
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Page/Page column 5-6

(2008/06/13)

Process for the production of di-and polyamines of the diphenylmethane series
Di- and polyamines of the diphenylmethane series are produced by a) converting nitrobenzene and methanol in the presence of a catalyst to aniline, formaldehyde and carbon monoxide, and then b) converting the aniline and formaldehyde produced in step a) in the presence of an acid catalyst to di- and polyamines of the diphenylmethane series, and c) converting the carbon monoxide produced in step a) with chlorine to phosgene.
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Page/Page column 4

(2008/06/13)

Aromatic monoanhydride-esters
Aromatic monoanhydride-esters of the formula (I) STR1 wherein R1 is STR2 and R2 is hydrogen, C1 -C4 alkyl or --OCH3 are useful as endcapping agents for the synthesis of multifunctional high temperature resins such as polyimides, polyimide-esters, polyimide-ethers and polyimide-amides.
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(2008/06/13)

The 2,1-Benzisothiazolo-2,1-benzisothiazole System, Synthesis and Properties
2,2'-Diaminodiphenylmethane and its 4,4'-dibromo-derivative both react with N-sulfinylmethanesulfonamide to form 2,1-benzisothiazole derivatives.Methylation or acetylation of these provides examples of the hypervalent sulfur 2,1-benzisothiazolo-2,1-benzisothiazole system.The nmr spectra of these compounds are discussed.
McKinnon, David M.,Duncan, K. Ann
p. 1095 - 1098
(2007/10/02)

On the Quantitative Determination of Some Different Condensation Products of Aniline and Formaldehyd by Different Chromatographic Methods
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Falke, P.,Tenner, R.,Knopp, H.
p. 142 - 148
(2007/10/02)

PROTODEALKYLATION OF BIS(AMINOPHENYL)METHANES
Contrary to earlier reports, the formation of bis(aminophenyl)methanes in the acid-catalyzed condensation of aniline and formaldehyde can result in carbon-carbon bond cleavage proceeding via an ipso protodealkylation mechanism.
Whitman, Peter J.,Frulla, Floro F.,Temme, George H.,Stuber, Fred A.
p. 1887 - 1890
(2007/10/02)

ELECTROCHEMICAL REDUCTION OF 2,2'-DINITRODIPHENYLMETHANE AND 2,2'-DINITROBENZOPHENONE AT MERCURY ELECTRODES
The last two compounds in a 5-membered series of aromatic dinitrocompounds are reduced in a completely different manner at mercury electrodes. 2,2'-Dinitrodiphenylmethane (I) - in which a conjugation of both symmetrical moieties is ruled out - is electrolytically reduced in an eight-electron step to a bishydroxylamine this being most stable between pH 4.5 and 5.0.In processing the catholyte increase in concentration of this product leads to its intermolecular disproportionation, resulting in the formation of dibenzo-1,2-diazepine 5-oxide (IV) and2,2'-diaminodiphenylmethane (III). 2,2'-Dinitrobenzophenone (II) reduces at more positive potentials.Its preparative electrolysis in acetonitrile (with 0.1M-N(n-C4H9)4PF6 as supporting electrolyte) the application of which was made necesarry by the low solubility of II in ethanol, proceeds in an anomalous way.In the most positive cathodic wave a radical anion results, the following cathodic wave corresponds to a 6-electron reduction of one nitro group to an amino group while the other nitro group splits off as the anion NO2(-) (this later giving an anodic wave).Its formation has been proved by standard addition in polarography and by a qualitative analytical test.The product which results through this electrode process and a follow-up chemical reaction is acridone.This is turn, reduces in the third, most negative 4-electron wave to dihydroacridine.The comparison of all substances studied in this series reveals that their reducibility decreases with respect to the link X, viz. in the sequence CO > O > S and CH2 > NH.The electrolytical reduction on mercury cathodes occurs in a similar manner with analogues where X=O, S or CH2.Here, the main intermediate is the bis-hydroxylamine the stability of which predetermines the structure of final products.The other group comprises the substances with X=CO and NH.Here the main intermediate is the 2-nitro-2'-amino-diphenyl-X which is formed in a 6-electron process taking place at one of the nitro groups.The follow-up cyclization reaction leading to seven-membered heterocyclic rings located between two benzene nuclei only occurs with analogues of the type X=CH2, O and S.A partial reduction of dinitro compounds of this series has been observed with the analogue containing the NH link although that with X=CO has generally good preconditions for this mechanism.
Voigtlaender, Rolf,Hlavaty, Jaromir,Volke, Jiri,Bakos, Viktor
p. 364 - 378
(2007/10/02)