- Synthesis and antitussive activity of obtucarbamate A derivatives
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Obtucarbamate A was purified from Disporum cantoniense with good antitussive property. In present work, a series of obtucarbamate A derivatives were designed and synthesized from obtucarbamate A by microwave method, and their antitussive activity were evaluated. The results showed that the toluene diisocyanate was obtained with a yield of 95.1percent using a simple method, 1-methyl-2-pyrrolidinone as solvent, temperature of 190 °C, microwave irradiation at 60 W power for 30 min. All compounds have good antitussive activity, and small steric hindrance unsaturated groups of ester chains and amino groups favor activity. It is the first reported of obtucarbamate A derivatives used as antitussive, and the results provide a basis for the application of obtucarbamate derivatives as new antitussive.
- Gan, Xiuhai,Liang, Zhiyuan,Ma, Xiaoyun,Wei, Gang,Zhou, Qingdi
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- N-Substituted carbamate synthesis using urea as carbonyl source over TiO2-Cr2O3/SiO2 catalyst
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The use of urea as an active form of carbon dioxide is a feasible way to substitute phosgene in the chemical industry. This paper reports an effective route for the synthesis of N-substituted carbamates from amines, urea and alcohols. Under the optimized reaction conditions, several important N-substituted carbamates were successfully synthesized in 95-98% yields over a TiO2-Cr2O3/SiO2 catalyst. The catalyst could be reused for several runs without deactivation. The catalysts were characterized by BET, XPS, XRD, and TPD, which suggested that the strength and amount of the acidic and basic sites might be the major reason for the high catalytic activity of TiO2-Cr2O3/SiO2.
- Wang, Peixue,Ma, Yubo,Liu, Shimin,Zhou, Feng,Yang, Benqun,Deng, Youquan
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p. 3964 - 3971
(2015/07/15)
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- Mild and high-yielding molybdenum(VI) dichloride dioxide-catalyzed formation of Mono-, Di-, Tri-, and tetracarbamates from alcohols and aromatic or aliphatic isocyanates
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Both molybdenum(VI) dichloride dioxide (MoO2Cl2) and its dimethylformamide (DMF) complex catalyze the addition of alcohols to isocyanates giving carbamates. Most additions proceeded to completion at room temperature within 20 min using as little as 0.1 mol% of the catalyst when working on a 1-mmol scale or just 100 ppm working on a 20-mmol scale. Sterically encumbered substrates reacted to completion when 1 mol% of the catalyst was employed. Diols, triols, and tetraols reacted with monoisocyanates likewise, as did monofunctional alcohols and diisocyanates. These pairings furnished di-, tri-, tetra-, and dicarbamates, respectively. Reactants, which were poorly soluble in CH2Cl2 at room temperature required elevating the temperature and possibly choosing a higher-boiling solvent (ClCH 2CH2Cl, DMF) as well. Additions of diols to diisocyanates were feasible, too, giving polycarbamates as we presume. Copyright
- Stock, Christian,Brueckner, Reinhard
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p. 2309 - 2330
(2012/11/07)
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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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- N-substituted carbamates syntheses with alkyl carbamates as carbonyl source over Ni-promoted Fe3O4 catalyst
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A series of catalysts of magnetic iron oxide containing Ni with different nickel content were prepared with co-precipitation method and tested in the syntheses of N-substituted carbamates from various amines and alkyl carbamates. Under the optimized reaction conditions, various N-substituted carbamates were successfully synthesized with 90-98% isolated yield. The catalyst could be recovered based on the magnetic property of the catalyst and reused for five runs without deactivation. The catalysts were characterized with X-ray photoelectron spectroscopy, X-ray diffraction, temperature-programmed reduction, temperature-programmed desorption, and Moessbauer spectroscopy analyses. The results showed that the catalytic activity may be derived from the delicate synergy between Ni and Fe species resulted in specific basic sites. Quasi in situ FT-IR and isotopic tracer revealed that the formation of substituted urea was the key step and the N-substituted carbamate was formed via further alcoholysis of the substituted urea.
- Shang, Jianpeng,Guo, Xiaoguang,Shi, Feng,Ma, Yubo,Zhou, Feng,Deng, Youquan
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experimental part
p. 328 - 336
(2011/05/14)
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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 9
(2010/10/03)
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- A new access to quinazolines from simple anilines
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A new synthetic pathway to quinazolines is described. This new method uses hexamethylenetetramine in TFA and potassium ferricyanide in aqueous ethanolic KOH, starting from simple N-protected anilines. The method affords substituted quinazolines with high
- Chilin, Adriana,Marzaro, Giovanni,Zanatta, Samuele,Barbieri, Vera,Pastorini, Giovanni,Manzini, Paolo,Guiotto, Adriano
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p. 12351 - 12356
(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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- Process for the preparation of urethanes
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A process for the preparation of N,O-disubstituted urethanes. A substituted urea, an alcohol and a compound taken from the group consisting of N-unsubstituted urethanes, urea, polyurets and mixtures thereof at a temperature of 120°-350° C. The urethanes prepared by this process are particularly suitable for the preparation of isocyanates.
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- Process for the preparation of N,O-disubstituted urethanes suitable as a starting material for the preparation of isocyanates
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A process for the preparation of N,O-disubstituted urethanes. Primary amines and alcohols are reacted with organic compounds having carbonyl groups at 120° to 350° C. Suitable carbonyl-containing compounds include N-unsubstituted urethanes. N-mono-substituted, N,N'-disubstituted ureas, or polyureas may be used in combination with the N-unsubstituted urethane. The product urethanes are particularly suitable for the preparation of isocyanates.
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- Process for recycling noble metal catalysts used for the manufacture of aromatic urethanes
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A process for the preparation of an aromatic urethane by the reaction in solution of an aromatic nitro compound or aromatic amine in the presence of an oxidation agent, with a hydroxyl compound and carbon monoxide in the presence of a noble metal catalyst
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- Process for separating selenium, selenium compounds, sulfur and/or sulfur compounds from polyurethanes containing these elements and/or compounds
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A process for separating selenium, selenium compounds, sulfur and/or sulfur compounds from urethanes containing these elements and/or compounds by reacting said urethanes with an aqueous permanganate solution and then separating the resulting phase system.
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- Process for the production of urethanes
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A method for the production of a urethane by reacting an organic hydroxyl group-containing compound, carbon monoxide and an organic nitro-compound at a suitable pressure and reaction temperature in the presence of a catalyst system consisting of a mixture of a tertiary amine and a platinum group metal or platinum group metal compound.
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