- Consideration of roles of commercial TiO2 pigments in aromatic polyurethane coating via the photodegradation of dimethyl toluene-2,4-dicarbamate in non-aqueous solution
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Dimethyl toluene-2,4-dicarbamate (2,4-TDC) was selected as a model compound for aromatic polyurethane to investigate the photo-chemical behavior of commercial TiO2 pigments in non-aqueous solution. The UV-Visible spectrometry analysis results showed that the UV-shielding ability of the rutile TiO2 pigment was better than that of the anatase TiO2 pigment. Photodegradation experiments suggested that the photodegradation of 2,4-TDC was retarded by rutile TiO2 pigment, while accelerated by anatase TiO2 pigment. With the help of the degradation intermediates during the photodegradation process and calculated data, such as point charges and bond length, the preliminary photodegradation mechanism of 2,4-TDC was also briefly elucidated, including the addition of hydroxyl radicals and the cleavage of the carbamate side chain. Additionally, the photodegradation of 2,4-TDC was used to evaluate the photoreactivity of TiO2 pigments, this is proved to an efficient approach with potential application in industry.
- Zhou, Shuolin,Xu, Qiong,Xiao, Jiafu,Zhong, Wenzhou,Yu, Ningya,Kirk, Steven Robert,Shu, Tao,Yin, Dulin
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Read Online
- The method for preparing dicarbamate compounds from diamines and the catalyst thereof
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The present invention relates to a method of directly preparing a dicarbamate compound from a diamine compound, and more particularly to a method of directly preparing a dicarbamate compound by reacting a diamine compound with an alcohol compound in the presence of a mixed gas of carbon monoxide (CO) and oxygen (O2) using a Pd/MOx catalyst configured such that a palladium (Pd) active metal is supported on a metal oxide or metalloid oxide carrier.
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Paragraph 0074-0077; 0081-0082
(2022/01/12)
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- N-Aryl and N-Alkyl Carbamates from 1 Atmosphere of CO2
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We have successfully isolated and characterized the zinc carbamate complex (phen)Zn(OAc)(OC(=O)NHPh) (1; phen=1,10-phenanthroline), formed as an intermediate during the Zn(OAc)2/phen-catalyzed synthesis of organic carbamates from CO2, amines, and the reusable reactant Si(OMe)4. Density functional theory calculations revealed that the direct reaction of 1 with Si(OMe)4 proceeds via a five-coordinate silicon intermediate, forming organic carbamates. Based on these results, the catalytic system was improved by using Si(OMe)4 as the reaction solvent and additives like KOMe and KF, which promote the formation of the five-coordinated silicon species. This sustainable and effective method can be used to synthesize various N-aryl and N-alkyl carbamates, including industrially important polyurethane raw materials, starting from CO2 under atmospheric pressure.
- Chen, Ming-Yu,Choe, Yoong-Kee,Choi, Jun-Chul,Fukaya, Norihisa,Hamura, Satoshi,Koizumi, Hiroki,Matsumoto, Kazuhiro,Matsumoto, Seiji,Shigeyasu, Shinji,Takeuchi, Katsuhiko,Yuan, Hao-Yu
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supporting information
p. 18066 - 18073
(2021/12/08)
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- METHOD FOR PRODUCING CARBAMATE
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PROBLEM TO BE SOLVED: To provide a method that can produce carbamate with high yield and high selectivity, and excellent economical efficiency, using more different kinds of amines. SOLUTION: A method for producing carbamate has a reaction step where, in the presence of calcium carbide and potassium carbonate, a reaction is induced among amine, methanol, and carbon dioxide. The reaction step is preferably performed at a temperature of 165-180°C. The reaction step is preferably performed at a carbon dioxide pressure of 3-5 MPa. The reaction step is preferably performed using an acetonitrile solvent. SELECTED DRAWING: Figure 1 COPYRIGHT: (C)2021,JPOandINPIT
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Paragraph 0014-0024
(2021/08/13)
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- A green route to polyurethanes: Oxidative carbonylation of industrially relevant aromatic diamines by CO2-based methyl formate
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The oxidative carbonylation of toluene-2,4-diamine (TDA) with methyl formate (MF), which can be produced from CO2, provides a possible route for the non-phosgene production of isocyanate precursors and enables a valuable utilization of the greenhouse gas. Extensive analysis of the product spectrum has provided detailed insight into the reaction network leading to the target product toluene-2,4-dicarbamate (TDC) and the most important side products. The most prominent one has been identified as methylene-bridged tetracarbamate 5, which is also an interesting precursor for applications in polyurethane chemistry. The side products are caused by three different reaction paths: N-formylation by MF, condensation with in situ formed formaldehyde, and N-methylation by in situ formed dimethyl carbonate (DMC). The influence of the catalyst on product distribution was evaluated for PdCl2/CuCl2 and a large number of heterogeneous Pd-catalysts. The oxidic support materials ZrO2, CeO2 and SiO2 were found to partially suppress the undesired side reactions leading to higher yields of TDC and tetracarbamate 5. The ratio of TDC to 5 was demonstrated to be affected significantly by the choice of the support. The synthetic protocol was extended to the synthesis of dicarbamates from 4,4′-methylenedianiline (MDA) and 2,4-diaminomesitylene (17). These results encourage further investigations into the design of selective catalysts for the production of isocyanate precursors from CO2 as a C1 source.
- Hussong, Christine,Langanke, Jens,Leitner, Walter
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supporting information
p. 8260 - 8270
(2020/12/31)
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- Calcium carbide as a dehydrating agent for the synthesis of carbamates, glycerol carbonate, and cyclic carbonates from carbon dioxide
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Carbon dioxide (CO2) is a nontoxic and inexpensive C1 building block, which can be used for the synthesis of valuable chemicals such as aromatic carbamates from anilines and methanol (MeOH), glycerol carbonate from glycerol, and cyclic carbonates from diols. However, these reactions generate water as the byproduct and suffer from thermodynamic limits, which lead to low yields. Calcium carbide (CaC2) is a renewable chemical, which can be recycled from calcium that is abundant in the Earth's crust. Furthermore, CaC2 rapidly reacts with water. In this work, we used CaC2 as a dehydrating agent for the direct synthesis of carbamates (including polyurethane precursors) from amines, CO2, and MeOH. All reagents were commercially available. In addition, CaC2 was employed for the synthesis of glycerol carbonate from glycerol and CO2 with a zinc catalyst and N-donor ligand. A similar protocol was applied to synthesize cyclic carbonates from diols and CO2.
- Choi, Jun-Chul,Fujitani, Tadahiro,Fukaya, Norihisa,Lin, Xiao-Tao,Sato, Kazuhiko,Yuan, Hao-Yu,Zhang, Qiao
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p. 4231 - 4239
(2020/10/02)
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- CuSe2/CeO2 as a novel heterogeneous catalyst for reductive carbonylation of nitroarenes for generating urethanes
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The reaction of CuCl2, SeO2, and cetyltrimethylammonium bromide (CTAB) under the CO pressure in methanol produce a black solid, which is identified as cupric diselenide, CuIISe2 using various spectroscopic analyses. Impregnation of 5 wt% of CuSe2 onto CeO2 resulted in much more enhanced catalytic activity due to the uniform and highly dispersed particle. The reductive carbonylation of nitrobenzene (NB) as a model substrate has been examined in the presence of the CuSe2/CeO2 as a single component heterogeneous catalyst, which is found to exhibit excellent catalytic activity for generating methyl-N-phenyl carbamate (MPC) in a highly selective fashion. The effects of various reaction parameters such as temperature, pressure, and reaction time have been investigated. A plausible reaction mechanism using this cheap heterogeneous catalyst is also presented, especially invoking the importance of CuSe2(μ-CO) species.
- Tran, Anh Vy,Nguyen, Thanh Tung,Lee, Hye Jin,Bae, Se Won,Baek, Jayeon,Kim, Hoon Sik,Kim, Yong Jin
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- PRODUCTION METHOD OF CARBAMIC ACID ESTER
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A method of production of carbamic acid ester has a high yield and high selectivity and is superior in economy. The method of production of a carbamic acid ester includes reacting an amine, carbon dioxide, and an alkoxysilane compound in the presence of a catalyst containing a zinc compound or an alkali metal compound or in the presence of an ionic liquid. A carbamic acid ester is produced, for example by reacting aniline, carbon dioxide, and tetramethoxysilane at a temperature of 150 to 180° C. in the presence of zinc acetate and 2,2′-bipyridine.
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Paragraph 0048; 0051
(2019/07/03)
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- Zr-MOF-808@MCM-41 catalyzed phosgene-free synthesis of polyurethane precursors
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In this work, a catalytic method is presented for the synthesis of aromatic carbamates from aromatic amines using dimethyl carbonate instead of phosgene as a green and safe reaction process. Microcrystalline Zr-MOF-808 is reported as an active and efficient heterogeneous catalyst for the selective carbamoylation of anilines and industrially relevant aromatic diamines, under mild reaction conditions with near quantitative yields. We have accomplished the selective growth of well-dispersed Zr-MOF-808 nanocrystals within the mesoporous material MCM-41. A superior catalytic performance of the Zr-MOF-808@MCM-41 is demonstrated that together with increased stability stands out as an advantageous heterogeneous catalyst for polyurethane production. In situ FTIR studies have allowed a better understanding of the reaction pathway at the molecular level when the active MOF catalyst is present.
- Rojas-Buzo, Sergio,García-García, Pilar,Corma, Avelino
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p. 146 - 156
(2019/01/10)
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- HETEROGENEOUS CATALYSTS FOR THE SYNTHESIS OF CARBAMATES
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The present invention relates to a catalyst for preparing carbamates, in particular aromatic carbamates, comprising a binary oxide having the formula Li_xMx02, wherein 1. is a metal selected from the lanthanoid series and M is a metal selected from the group consisting of Sc, Y, Ti, Zr, Hf, metals from the lanthanoid series and metals from the actinoid series, and wherein x ranges from 0.01 to 0.05. The present invention also relates to a method for producing said catalysts and a method of utilizing said catalysts in the production of carbamates, in particular aromatic carbamates.
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Page/Page column 16; 19-20
(2019/10/23)
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- SILICA-BASED ZINC CATALYSTS. THEIR PREPARATION AND USE IN THE ALKOXYCARBONYLATION OF AMINES
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The present invention relates to silica-based heterogeneous zinc compounds which are suitable as catalysts in the reaction of amines with dialkyl carbonates to produce carbamates. The catalysts have the formula [SiO2]-CH2-CHR-X-COOZn[Y], wherein [SiO2] represents a silica carrier selected from the group consisting of ordered mesoporous silica and irregular amorphous narrow pore silica, R represents a moiety selected from the group consisting of hydrogen, -CH3, and -CH2CH3, preferably hydrogen, X is an aliphatic chain of 2 to 11 carbon atoms that optionally comprises ether moieties and [Y] represents a mono anion. The invention is also directed towards a method for the preparation of the aforementioned compounds and towards method for the alkoxycarbonylation of amines.
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Page/Page column 22-28
(2018/12/13)
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- Direct Catalytic Synthesis of N-Arylcarbamates from CO2, Anilines and Alcohols
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The direct catalytic synthesis of carbamates from CO2, amines and methanol was achieved by controlling both the reaction equilibrium and the reactivity of the three components. The combination of CeO2 and 2-cyanopyridine was an effective catalyst, providing various carbamates including N-arylcarbamates in high selectivities.
- Tamura, Masazumi,Miura, Ayaka,Honda, Masayoshi,Gu, Yu,Nakagawa, Yoshinao,Tomishige, Keiichi
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p. 4835 - 4839
(2018/10/15)
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- Phosgene-free synthesis of carbamates using co2 and titanium alkoxides
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A facile one-pot, phosgene-free method for the synthesis of N-phenylcarbamates is developed. Using this method, various aromatic carbamates could be prepared from aromatic amines, CO2 and metal alkoxides. Aniline reacted with titanium methoxide (Ti(OMe)4)) in the presence of CO2 (5 MPa) to give methyl N-phenylcarbamate in 85% yield, in 20min. Titanium residue could be regenerated by reaction with dimethyl carbonate at 220 °C for 16 h.
- Yuan, Hao-Yu,Zhang, Qiao,Fukaya, Norihisa,Lin,Fujitani, Tadahiro,Choi, Jun-Chul
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p. 1481 - 1486
(2018/10/25)
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- Metal-Free Synthesis of Unsymmetrical Ureas and Carbamates from CO2 and Amines via Isocyanate Intermediates
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A mild and metal-free synthesis of aryl isocyanates from arylamines under an atmosphere of CO2 was developed. The carbamic acid intermediate, derived from the arylamine starting material and CO2 in the presence of DBU, is dehydrated by activated sulfonium reagents to generate the corresponding isocyanate. The latter can be detected by in situ IR and trapped by various amines and alcohols to make unsymmetrical ureas and carbamates, respectively. Dicarbamates can also be prepared in good yields via the mild dehydration of the corresponding dicarbamic acids.
- Ren, Yiming,Rousseaux, Sophie A. L.
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p. 913 - 920
(2018/01/28)
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- A PROCESS FOR THE SYNTHESIS OF AROMATIC CARBAMATES
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The present invention discloses a process for the synthesis of aromatic carbamates from amine with dialkyl carbonate in the presence of binary or ternary mixed metal oxide catalyst. The present invention further discloses the yield of said aromatic carbamate in the range of 60 to 99%. Further, the ratio of amine to dialkyl carbonate is in the range of 1:2 to 1:30.
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Page/Page column 15
(2018/12/13)
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- Method for preparing methyl carbamate by catalyzing methanol conversion
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The invention discloses a method for preparing methyl carbamate by catalyzing methanol conversion. The method specifically comprises: taking oxygen or air as an oxygen source, taking organic amine as a nitrogen source, taking methanol as a solvent, in the function of a catalyst, allowing methanol to undergo ammoxidation to generate methanamide, and allowing methanamide to undergo in-situ oxidation esterification to obtain methyl carbamate. The method is high in raw material utilization rate. The catalyst is cheap and available, is easy to recycle, can be reused, and is easy to separate from the product. The obtained methyl carbamate is excellent in performance and high in purity. The technical route is of great significance in releasing excess production capacity of methanol and reducing the dependence on highly toxic chemicals.
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Paragraph 0033
(2018/01/09)
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- Direct synthesis of carbamate from CO2 using a task-specific ionic liquid catalyst
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A superbase-derived protic ionic liquid (IL, [DBUH][OAc]) catalyst was used to directly synthesize carbamate from an amine, CO2, and a silicate ester. This IL catalyst was easily prepared using its precursors, DBU, and acetic acid. Using 10 mol% of the catalyst under a CO2 pressure of 5 MPa in acetonitrile at 150 °C, carbamate was isolated in up to 96% yield. Specifically, aliphatic and aromatic amines were activated even though aromatic amines exhibited low activities because of their low pKa values. Other functional groups in amines were barely activated, affording exclusive chemoselectivity for amine activation. Isotope labeling experiments indicated that the proton in the counter cation is crucial in the catalytic cycle to produce water. In addition, a chemical shift corresponding to a mixture of aniline and [DBUH][OAc] was observed in the 1H NMR spectrum, related to the formation of hydrogen bonds between aniline and basic acetate anions. The experimental results indicated that the designed IL catalysts require a protonated cation and a basic anion.
- Zhang, Qiao,Yuan, Hao-Yu,Fukaya, Norihisa,Yasuda, Hiroyuki,Choi, Jun-Chul
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p. 5614 - 5624
(2017/12/06)
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- Biotransformation of isofraxetin-6-O-β-D-glucopyranoside by Angelica sinensis (Oliv.) Diels callus
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Isofraxetin-6-O-β-D-glucopyranoside, identified from traditional medicinal herbal Xanthoceras sorbifolia Bunge, has been demonstrated to be a natural neuroinflammatory inhibitor. In order to obtain more derivatives with potential anti-neuroinflammatory effects, biotransformation was carried out. According to the characteristics of coumarin skeleton, suspension cultures of Angelica sinensis (Oliv.) Diels callus (A. sinensis callus) were employed because of the presence of diverse phenylpropanoids biosynthetic enzymes. As a result, 15 products were yielded from the suspension cultures, including a new coumarin: 8′-dehydroxymethyl cleomiscosin A (1), together with 14 known compounds. Their structures were elucidated by extensive spectroscopic analysis. Furthermore, the biotransformed pathways were discussed. Among them, compound 13 was transformed from isofraxetin-6-O-β-D-glucopyranoside, while compounds 1–6, 10–12, 14–15 were derived from the culture medium stimulated by the substrate. The biotransformation processes include hydroxylation, oxidation and esterification. Furthermore, their inhibitory effects on lipopolysaccharide (LPS)-activated nitric oxide (NO) production were evaluated in BV2 microglial cells. It is worth noting that, 1, 1′-methanediylbis(4-methoxybenzene) (3), obtucarbamates A (5), 2-nonyl-4-hydroxyquinoline N-oxide (10) and 1H-indole-3-carbaldehyde (11) exhibited significant inhibitory effect against neuroinflammation with IC50values at 1.22, 10.57, 1.02 and 0.76?μM respectively, much stronger than that of the positive control minocycline (IC5035.82?μM).
- Zhou, Di,Zhang, Yuhua,Jiang, Zhe,Hou, Yue,Jiao, Kun,Yan, Chunyan,Li, Ning
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p. 248 - 253
(2016/12/27)
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- PROCESS FOR PREPARING ISOCYANATE COMPOUND
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The present invention relates to a process for the preparation of an isocyanate compound comprising the steps of: a) Reacting an amine compound A having at least one primary amino group with CO2 and an organotin compound S having at least one radical OR3 attached to the tin atom of the organotin compound, wherein R3 is a C-bound organic radical having from 1 to 30 carbon atoms, wherein 1, 2 or 3 carbon atoms may be replaced by oxygen or nitrogen, to convert at least one of the primary amino groups in the amine compound A into a carbamate group, thereby obtaining a carbamate compound C; b) cleavage of the carbamate groups in the carbamate compound C obtained in step a) to form the isocyanate compound and an alcohol R3OH, without separation of the tin compound formed in step a); c) obtaining the isocyanate compound from the reaction mixture of step b).
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Page/Page column 20
(2016/11/21)
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- ZINC CLUSTER COMPOUNDS AND THEIR USE AS CATALYSTS IN THE REACTION OF AMINES WITH DIALKYL CARBONATES
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The present invention relates to metallic zinc cluster compounds which are suitable as catalysts in the reaction of amines with dialkyl carbonates to produce carbamates. The invention is also directed towards a method for the alkoxycarbonylation of amines. The cluster compound has a general formula which may be written as [M(O2C-R)2]x- [MO]y- [H2O]z, wherein M is Zn, R is an unsubstituted or substituted aromatic, cycloaliphatic, linear aliphatic, or other organic rest, x is 1, y is > x is 1, y is > 0.03 to 0.00 to 17.0.
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Page/Page column 12
(2014/12/12)
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- ONE-POT PRODUCTION OF CARBAMATES USING SOLID CATALYSTS
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The invention relates to the production of carbamates in a single reactor (one-pot) using solid catalysts, involving the reaction between at least one nitro compound, an organic carbonate of formula (OR)(OR')C=O, a gas selected from hydrogen gas and a mixture of gases containing hydrogen and hydrogen precursor compounds, and a catalyst that has at least one metallic oxide and can also contain an element of groups 8, 9, 10 and 11 of the periodical table. The carbonates obtained can be transformed into their corresponding isocyanates.
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Page/Page column 5
(2012/02/04)
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- ONE-POT PRODUCTION OF CARBAMATES USING SOLID CATALYSTS
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The invention relates to the production of carbamates in a single reactor (one-pot) using solid catalysts, involving the reaction between at least one nitro compound, an organic carbonate of formula (OR)(OR′)C═O, a gas selected from hydrogen gas and a mixture of gases containing hydrogen and hydrogen precursor compounds, and a catalyst that has at least one metallic oxide and can also contain an element of groups 8, 9, 10 and 11 of the periodical table. The carbonates obtained can be transformed into their corresponding isocyanates.
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Page/Page column 3
(2012/03/12)
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- PREPARATION OF CARBAMATES WITH SOLID CATALYSTS
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Procedure for preparing carbamates comprising reaction between at least: an amine or polyamines, an organic carbonate of formula (OR)(OR')C=O, a catalyst formed at least by a support selected from among at least a metal oxide, a microporous material, a mesoporous material, an anionic laminar compound of the hydrotalcite type or derivatives thereof or an organic polymer and which may also contain a metal from groups 8, 9, 10 and 11 of the periodic system. The carbamates obtained may be converted into the corresponding isocyanates thereof.
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Page/Page column 7-8
(2011/05/08)
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- CATALYST FOR PRODUCING N-SUBSTITUTED CARBAMATES, AND THE PREPARATION AND APPLICATION OF THE SAME
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The present invention relates to a novel catalyst for producing N-substituted carbamates, the preparation of the catalyst and an improved method for producing N-substituted carbamates from these novel catalysts. The active component of the catalyst is a heteropoly acid and the catalyst support comprises a metal oxide or a metalloid oxide. The catalyst can be used to promote the reaction of carbamate and amine, thereby generating N-substituted carbamates with high yield. In the presence of the catalyst, the reaction conditions are relatively mild, the catalytic activity and selectivity of the reaction are high, and the reaction time is relatively short. Furthermore, the catalyst can be conveniently separated from the reaction system and recycled. therefore, the catalyst can be used to facilitate the further scale-up test and commercial application.
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Page/Page column 8
(2010/12/29)
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- 1H NMR analysis of the tolylene-2,4-diisocyanate-methanol reaction
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Tolylene-2,4-diisocyanate (2,4-TDI) 1 reacts with methanol through two simultaneous paths in the polyurethane reaction, which involve two different intermediates - tolylene-4-carbamatic-2-isocyanate 2 and tolylene-2-carbamatic- 4-isocyanate 3, and the final product is tolylene-2,4-dicarbamate 4. The-CH 3 chemical shifts in benzene ring in compounds 1, 2, 3 and 4 can be easily tested and well distinguished, through which those four compounds are quantified and their kinetics are investigated. It shows that four rate constants for the tolylene-2,4-diisocyanate-methanol reaction in CCl4 at 50°C are k1 = 9.6 × 10-2 h-2 mol-2 min-1, k2 = 1.4 × 10-2 h-2 mol-2 min-1, k3 = 4.0 × 10-3 h-2 mol-2 min-1, k4 = 1.4 × 10-3 h-2 mol-2 min-1. (k1 is the reaction rate constant from compounds 1 to 2; k 2 is the reaction rate constant from compounds 1 to 3; k3 is the reaction rate constant from compounds 3 to 4; k4 is the reaction rate constant from compounds 2 to 4).
- Yang, Peng Fei,Han, Yong De,Li, Tian Duo,Li, Jun Ying
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experimental part
p. 853 - 855
(2011/12/16)
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- Gold-catalyzed phosgene-free synthesis of polyurethane precursors
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(Figure Presented) Golden catalyst: In a two-step one-pot catalytic process gold nanoparticles supported on CeO2 are able to convert nitroaromatics into aromatic carbamates, thereby providing an alternative phosgene-free route towards aromatic polyurethanes (see figure).
- Juarez, Raquel,Concepcion, Patricia,Corma, Avelino,Fornes, Vicente,Garcia, Hermenegildo
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experimental part
p. 1286 - 1290
(2010/05/18)
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- Process for preparing aromatic carbamates
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The invention is directed to a process for preparing aromatic carbamates which comprises the reaction of an aromatic amine with an organic carbonate in the presence of a catalyst characterized in that Zn4O(OAc)6 is used as catalyst.
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Page/Page column 8; 9
(2010/10/03)
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- METHOD FOR PRODUCTION OF ISOCYANATE USING COMPOSITION COMPRISING CARBAMIC ACID ESTER AND AROMATIC HYDROXY COMPOUND, AND COMPOSITION FOR TRANSPORT OR STORAGE OF CARBAMIC ACID ESTER
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An object of the present invention is to provide an isocyanate production process, which is free of the various problems found in the prior art, and which uses a composition containing a carbamic acid ester and an aromatic hydroxy compound when producing isocyanate without using phosgene, as well as a carbamic acid ester composition for transferring or storing carbamic acid ester. The present invention discloses an isocyanate production process including specific steps and using a composition containing a carbamic acid ester and an aromatic hydroxy compound, as well as a composition for transfer or storage of carbamic acid ester comprising the carbamic acid ester and the specific aromatic hydroxy compound.
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Page/Page column 60
(2010/02/17)
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- PROCESS FOR PRODUCING ISOCYANATE
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An object of the present invention is to provide a process allowing long-term, stable production of isocyanates at a high yield without the various problems found in the prior art during production of isocyanates without using phosgene. The present invention discloses a process for producing an isocyanate by subjecting a carbamic acid ester to a decomposition reaction in the presence of a compound having an active proton and a carbonic acid derivative.
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Page/Page column 51
(2009/09/05)
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- Efficient palladium/1,10-phenanthroline-catalyzed reductive carbonylation of mono- and dinitroarenes to urethanes in phosphonium salt ionic liquids
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(Chemical Equation Presented) The highly reactive and selective reductive carbonylation of mono- and dinitroarenes to the corresponding mono- and diurethanes was carried out in the presence of a PdCl2/Phen catalytic system, using PSIL110[C14H29(C6H 13)3P+PF6-] as the ionic liquid under mild reaction conditions. No cocatalyst is required.
- Yang, Qian,Robertson, Al,Alper, Howard
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experimental part
p. 5079 - 5082
(2009/05/07)
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- Heterogeneous Supported Catalytic Carbamate Process
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A process for the preparation of aromatic carbamates comprising contacting one or more organic carbonates with an aromatic amine or urea in the presence of a catalyst and recovering the resulting aromatic carbamate product, characterized in that the catalyst is a heterogeneous catalyst comprising a Group 12-15 metal compound supported on a substrate.
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Page/Page column 4; 6; 7; 9
(2008/12/07)
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- PRODUCTION OF N-ARYL CARBAMATES AND N-ARYL ISOCYANATES
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The invention relates to a method for producing N-aryl carbamates (urethanes) and N-aryl isocyanates. According to said method, aromatic nitro compounds are subjected to a reductive carbonylation in the presence of carbon dioxide and organic compounds that bear hydroxyl groups and the carbonylation is carried out in the presence of metal complexing catalysts. Anionic N,O-chelate ligands of the general formulae [M(N~O)-2] and [M(O~N~N~O)2-], containing a divalent or trivalent transition metal of groups 5 - 11 are used for the catalysts.
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Page/Page column 20
(2008/06/13)
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- Carbonylation of dinitrotoluene to dimethyl toluenedicarbamate; high efficiency of phosphorus acids as promoters for the palladium-phenanthroline catalytic system
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Phosphorus acids are excellent promoters for the palladium-phenanthroline catalyzed carbonylation of 2,4-dinitrotoluene to 2,4-toluenedicarbamate. For the first time, all intermediate nitrocarbamates and aminocarbamates have been independently synthesized and their amount after every catalytic reaction precisely quantified. An extensive optimization of all experimental variables has been carried out. The best acids are phenylphosphonic and 4-tolylphosphonic acids. The addition of 2,2-dimethoxypropane as an internal drying agent is highly beneficial. The addition of an amine derived from the starting dinitroarene increases both rate and selectivity of the carbonylation reaction. The complexes [Pd(Phen)2] [SbF6] and [Pd(Phen) 2][BArF4] [ArF = 3,5-(CF 3)2C6H3] have been prepared for the first time. The latter displays a markedly higher solubility than all other [Pd(Phen)2]2+ complexes. The effect of several possible promoters has also been investigated. Under the optimized experimental conditions, a 77.6% selectivity in dicarbamate was obtained when working at a molar ratio dinitrotoluene/Pd = 2920. At the end of the reaction, the dicarbamate spontaneously precipitates out of the solution in high yields upon cooling, with no inclusion of the acid promoter or of phenanthroline. 2,6-Dinitrotoluene can also be efficiently carbonylated to the corresponding dicarbamate.
- Gasperini, Michela,Ragaini, Fabio,Cazzaniga, Chiara,Cenini, Sergio
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p. 105 - 120
(2007/10/03)
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- The palladium-phenanthroline catalyzed carbonylation of nitroarenes to diarylureas: Effect of chloride and diphenylphosphinic acid
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The application of the palladium-phenanthroline catalytic system to the carbonylation of nitrobenzene in the presence of aniline to afford diphenylurea has been investigated. The reaction is best performed with equimolar amounts of the two reagents. Use of higher concentrations of either aniline or nitrobenzene or an increase in temperature in the range 120-170 °C leads to the formation of higher amounts of azo- and azoxybenzene. The latter were found to contain exclusively the aryl moiety deriving from nitrobenzene, with no inclusion of that derived from aniline. The addition of a small amount of diphenylphosphinic acid doubles the conversion and improves the selectivity in diphenylurea, but the effect is attenuated for larger amounts of acid. Small amounts of chloride, of the order of 10-30 mol% with respect to palladium, improve both rate and selectivity, but only inhibiting effects are detected when chloride is added to the reaction mixture for the carbonylation of 2,4-dinitrotoluene to dimethyl 2,4-toluenedicarbamate. The data obtained and that previously reported in the literature has been analyzed in the context of a unifying mechanism and an explanation for some apparent contradictions has been given.
- Gasperini, Michela,Ragaini, Fabio,Remondini, Chiara,Caselli, Alessandro,Cenini, Sergio
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p. 4517 - 4529
(2007/10/03)
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- First gold(I) complex-catalyzed oxidative carbonylation of amines for the syntheses of carbamates
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At 200 °C and 5 MPa of initial total pressure, the oxidative carbonylation of amines for the synthesis of the corresponding carbamates by Au(I) complexes as catalysts was conducted with excellent conversion and selectivity.
- Shi,Deng
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p. 443 - 444
(2007/10/03)
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- Synthesis of alkyl N-(C-nitrosoaryl)carbamates and some reactions thereof
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Reactions of alkyl N-phenylcarbamates, m-di(methoxycarboxyamido)benzene, and methyl N-(o-tolyl)carbamate with nitrosylsulfuric acid in glacial acetic acid afford N-(C-nitrosoaryl)carbamates; under these conditions tert-bulyl N-phenylcarbamate suffers decarboxylation, methyl N-(p-tolyl)-, methyl N-(p-methoxyphenyl)carbamates, o-and p-di(methoxycarboxyamido)benzenes are nitrated, and isomeric methyl N-nitrophenylcarbamates and methyl N-(p-bromophenyl)carbamate do not react. The reduction of N-(C-nitrosoaryl)carbamates with dithionite afforded the corresponding aminocarbamates; the oxidation with nitric acid yielded carbamate nitro derivatives; the condensation with aniline and benzylpyridinium chloride resulted in carbamate derivatives of azobenzene and phenylnitron.
- Velikorodov
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p. 233 - 239
(2007/10/03)
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- Reductive carbonylation of aromatic dinitro compounds with a palladium(phenanthroline)2(triflate)2 catalyst and an aromatic carboxylic acid as cocatalyst
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Reductive carbonylation of aromatic dinitro compounds to afford valuable dicarbamates proceeds at reasonable rates and with high selectivities under the influence of a Pd(phenanthroline)2(triflate)2 catalyst in combination with an aromatic carboxylic acid as cocatalyst.
- Wehman, Petra,Kamer, Paul C. J.,Van Leeuwen, Piet W. N. M.
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p. 217 - 218
(2007/10/03)
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- The Biodegradation of Low-molecular-weight Urethane Compounds by a Strain of Exophiala jeanselmei
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To further analyze the biodegradation of polyurethane polymers, we investigated the biodegradation of low-molecular-weight N-tolylcarbamate model compounds with structures closely resembling the urethane linkages found in polyurethanes based on tolylene-diisocyanate (TDT). Soil microflora were screened for microorganisms that were able to utilize toluene-2,4-dicarbamic acid, diethyl ester (compound 1) as the sole source of carbon, and the soil fungus Exophiala jeanselmei strain REN-11A was selected as the most effective strain. Several N-tolylcarbamate compounds were used, and it was found that REN-11A was able to degrade compound 1, as well as the related compound toluene-2,6-dicarbamic acid, diethyl ester, very efficiently. Further investigation showed that compound 1 was biodegraded to tolylene-2,4-diamine via the aromatic amine intermediates carbamic acid, (3-amino-4-methylphenyl)-, ethyl ester and carbamic acid, (5-amino-2-methylphenyl)-, ethyl ester.
- Owen, Stephen,Otani, Takahito,Masaoka, Satoshi,Ohe, Tatsuhiko
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p. 244 - 248
(2007/10/03)
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- Palladium Complex-Potassium Carbonate-catalysed Reductive Carbonylation of Mono- and Di-nitroaromatic Compounds
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Mono- and di-nitroaromatic compounds react with carbon monoxide in benzene containing methanol, with catalytic quantities of 1,3-bis(diphenylphosphino)propanepalladium dichloride and potassium carbonate as the base, to give urethanes in reasonable yields.
- Reddy, Nagavelli P.,Masdeu, Anna M.,Ali, Bassam El,Alper, Howard
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p. 863 - 864
(2007/10/02)
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- A spectroscopic study of the model urethanes
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The synthesis, far infrared spectra, temperature-dependent mid-infrared spectra in the carbonyl and NH streching regions and the Fourier transform Raman spectra are reported for polycrystalline samples of three small diurethanes, 1,3-phenyl di(carbamic acid methyl ester), 2,6-toluene di(carbamic acid methyl ester) and 2,4-toluene di(carbamic acid methyl ester).An ab initio geometry optimization is reported for methyl N-phenyl carbamate using STO-3G and 3-21G basis sets, and for the three small diurethanes by molecular machanics methods using the Dreiding I force field.The results suggest that, in isotropic surroundings, only a very small number of the 256 posible conformers of the urethane groups in the three small diurethanes contribute appreciably to the structure.
- Wang, Qiong,Stidham, Howard D.,Papadimitrakopolos, F.
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p. 421 - 434
(2007/10/02)
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- Selective Ruthenium Carbonyl Catalysed Reductive Carbonylation of Aromatic Nitro Compounds to Carbamates
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Ru3(CO)12 and Ru(CO)3(PPh3)2 catalyse the reductive carbonylation of aromatic nitro compounds to the corresponding carbamates with high selectivity in the presence of NEt4+Cl- as co-catalyst.
- Cenini, Sergio,Pizzotti, Maddalena,Crotti, Corrado,Porta, Francesca,Monica, Girolamo La
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p. 1286 - 1287
(2007/10/02)
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