2603-10-3Relevant articles and documents
Oxidation of thionocarbamates into sulfur free carbamates by an idodine DMSO system
Kinoshita,Kubota,Hashimoto,Ishikawa
, p. 701 - 702 (1973)
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Self-assembly of ionic liquids and metal complexes in super-cages of NaY: Integration of free catalysts and solvent molecules into confined catalytic sites
Ma, Yubo,He, Yude,Zhang, Qinghua,Shi, Feng,Ma, Xiangyuan,Lu, Liujin,Deng, Youquan
, p. 933 - 937 (2010)
The integration of a free metal complex, Pd(phen)2+, and a room temperature ionic liquid (IL) solvent molecule, 1-decyl-3-methyl imidazolium bromide, into a complete catalytically active site and confined in a NaY zeolite super-cage with an appropriate spatial arrangement was investigated. This integration was achieved through a molecular self-assembly method. A preliminary test of this catalyst system for the carbonylation of aniline to methyl phenyl carbamate indicated that far higher catalytic activity could be achieved (TOF increased from 3 000 to 23 000 h-1) with far lower amounts of the IL solvent and the Pd complex in comparison with a simple mixture of Pd(phen)Cl2/IL/NaY as the catalyst. This new system can also be applied to other areas of catalysis.
-, -, and bimetallic clusters as catalysts for carbonylation of nitrobenzene to methyl phenylcarbamate
Ragaini, Fabio,Cenini, Sergio,Fumagalli, Alessandro,Crotti, Corrado
, p. 401 - 408 (1992)
Bimetallic clusters of the general formula 2 (M = Fe, Ru, or Os; PPN- = (PPh3)2N+) are active catlysts in the presence of methanol for the carbonylation of nitrobenzene to methyl phenylcarbamate.The clusters are active even without co-catalyst, but the addition of bipy (2,2'-bipyridine) greatly enhances both rates and selectivities.In the absence of methanol the conversion was much lower, with a low selectivity in phenyl isocyanate.Interchanging Fe, Ru, and Os has a negligible effect on the activity and a moderate effect on the selectivity, with ruthenium being best.However, the monometallic rhodium cluster - proved to be both more active and selective, and the monomer - was found to be even better.This last catalytic system has been optimized with respect to temperature, CO pressure and the bipy/Rh ratio.The influence of solvent was also examined.
Oxidative carbonylation of aniline with a mesoporous silica gel immobilised Se-functionalised ionic liquid catalyst
Ma, Yubo,Shi, Feng,Deng, Youquan
, p. 344 - 347 (2010)
A series of BMImBF4-templated mesoporous silica gel immobilised Se-functionalised ionic liquids have been prepared. The catalysts were characterised by BET, FTIR and ICP-AES, and the results showed that the content of Se increased from 2.7 to 4.76 wt% with pore volume increasing from 0.83 to 1.26 cm3 g-1. Preliminary tests of this catalyst system on the carbonylation of aniline to afford methyl phenyl carbamate (MPC) indicated that good catalytic activity (higher than 74% aniline conversion with 99% MPC selectivity) could be achieved with higher than 150 mol h-1 mol -1 turnover frequency (TOF). TOF and aniline conversion slightly increased with increasing the content of Se from 2.7 to 3.0 wt%, then decreased when the content of Se increased to more than 3.0 wt%, this suggested that 2.7 to 3.0 wt% Se content should be appropriate for MPC synthesis. The appropriate Se content could be obtaineded by adjusting the range of pore volume of mesoporous silica gel from 0.83 to 0.85 cm3 g-1. In addition, the recycling test indicated that there was almost no deactivation of the catalyst when it was reused four times.
Franz
, p. 585 (1963)
Parker,Burgert
, p. 3341 (1968)
Highly selective phosgene-free carbamoylation of aniline by dimethyl carbonate under continuous-flow conditions
Grego, Sandra,Aricoi, Fabio,Tundo, Pietro
, p. 679 - 683 (2013)
Over the last 20 years organic carbamates have found numerous applications in pesticides, fungicides, herbicides, dyes, pharmaceuticals, cosmetics, and as protecting groups and intermediates for polyurethane synthesis. Recently, in order to avoid phosgene-based synthesis of carbamates, many environmentally benign and alternative pathways have been investigated. However, few examples of carbamoylation of aniline in continuous-flow apparatus have been reported. In this work, we report a high-yielding, dimethyl carbonate (DMC)-mediated carbamoylation of aniline in a fixed-bed continuously fed reactor employing basic zinc carbonate as catalyst. Several variables of the system have been investigated (i.e. molar ratio of reagents, flow rate, and reaction temperature) to optimize the operating conditions of the system.
Mechanistic study of the palladium - Phenanthroline catalyzed carbonylation of nitroarenes and amines: Palladium - Carbonyl intermediates and bifunctional effects
Ragaini, Fabio,Gasperini, Michela,Cenini, Sergio,Arnera, Lucia,Caselli, Alessandro,Macchi, Piero,Casati, Nicola
, p. 8064 - 8077 (2009)
Palladium - phenanthroline complexes catalyze both the nitroarene carbonylation reaction and the amine oxidative carbonylation reaction to give, depending on the conditions, carbamates and ureas. There is evidence that the key step in both processes is the amine carbonylation. Here, we show that when the reaction is run in methanol key intermediate compounds have the general formula [Pd(RPhen)(COOMe)2] (1) (RPhen = l,10-phenanthroline or one of its substituted derivatives). The kinetics of the reaction of 1 with toluidine in the presence of a carboxylic or phosphorus acid is firstorder with respect to complex, acid, and toluidine. A CO atmosphere is also required for the reaction to proceed. Acid dimerization was shown not to be influential under the concentration conditions examined, but reaction between the acid and toluidine is not negligible and a correction has to be applied. Diphenylphosphinic acid is more effective than any carboxylic acid in promoting this reaction, as also observed under catalytic conditions. A series of equilibria and an irreversible acid-assisted proton transfer explain the observed data. Formation of an adduct between complexes of the kind 1 and CO was spectroscopically observed when RPhen = 2,9-Me2Phen. Several analogous complexes were also spectroscopically characterized and the X-ray structure of [Pd(2,9Me2Phen)Cl2(CO)] was solved. This shows an asymmetric coordination of the nitrogen ligand. Kinetic measurements were also conducted under catalytic conditions. An Eyring plot shows that the effect of the acidic promoter is to decrease the ?S * value, whereas no positive effect is observed on ?H*. A temperature-dependent correction for the reaction between the acid and aniline and phenanthroline present under the reaction conditions has to be applied. Comparison of the results obtained under stoichiometric and catalytic conditions strongly supports the view that 1 is involved even in the latter and that the acid is acting as a bifunctional promoter.
Phosphorus acids as highly efficient promoters for the palladium- phenanthroline catalyzed carbonylation of nitrobenzene to methyl phenylcarbamate
Ragaini, Fabio,Gasperini, Michela,Cenini, Sergio
, p. 63 - 71 (2004)
A new family of promoters, based on phosphorus acids, is reported for the catalytic carbonylation of nitrobenzene to methyl phenylcarbamate by palladium-phenanthroline complexes. With the new promoters, unprecedented reaction rates (TOF up to 6000/h) and catalyst stability (TON up to 10 5) could be reached. The best promoter is phosphoric acid, which is also very cheap, nontoxic and easily separable from the reaction products.
Mineral Oil/Methanol: A Cheap Biphasic Reaction Medium with Thermomorphic Properties and Its Application to the Palladium-Catalyzed Carbonylation of Nitrobenzene to Methyl Phenylcarbamate
Ferretti, Francesco,Gallo, Emma,Ragaini, Fabio
, p. 2241 - 2247 (2015)
We developed the methanol/mineral oil system as a new thermomorphic solvent mixture that allows homogeneous catalyst recovery without the use of water or fluorinated solvents. Mineral oil (nujol) is cheap and shows a very limited miscibility with methanol at room temperature but becomes completely miscible at high temperatures. Here we report the synthesis of some phenanthrolines substituted with long-chain alkyl groups, which render them soluble in hydrocarbons and insoluble in methanol, and their application to the palladium-catalyzed carbonylation of nitrobenzene to methyl phenylcarbamate. Both the reagents and products of the catalytic reaction are much more soluble in methanol than in hydrocarbons, so an easy separation of the catalyst is possible.
N-Aryl and N-Alkyl Carbamates from 1 Atmosphere of CO2
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
supporting information, p. 18066 - 18073 (2021/12/08)
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.
CANNABINOID DERIVATIVES
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Paragraph 0154, (2021/06/22)
This disclosure relates generally to cannabinoid derivatives, pharmaceutical compositions comprising them, and methods of using the cannabinoid derivatives.
A convenient Hofmann reaction of carboxamides and cyclic imides mediated by trihaloisocyanuric acids
Bastos, Gustavo A.,de Mattos, Marcio C.S.
, (2021/09/29)
A simple, efficient and pot-economic approach in a single vessel has been developed for conversion of aromatic and aliphatic carboxamides into primary amines with one fewer carbom atom (Hofmann reaction) in 38–89 % yield by reacting with trichloro- or tribromoisocyanuric acid and sodium hydroxide in aqueous acetonitrile. Under the same reaction conditions, cyclic imides gave amino acids (69–83 %). The role of the trihaloisocyanuric acids is the in situ generation of N-haloamides, key-intermediates for the Hofmann reaction. The scalability of the methodology was demonstrated by a multigram-scale transformation of phthalimide into anthranilic acid in 77 % yield.
