- Organic ligand and solvent free oxidative carbonylation of amine over Pd/TiO2 with unprecedented activity
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A highly active Pd/TiO2 catalyst system was prepared and applied in the oxidative carbonylation of amines to ureas with ultra-low Pd content under organic ligand and solvent free conditions. The catalytic turnover frequencies (TOFs, moles of amines converted per mole of Pd per h) were 126000 and 250000 h-1 for the production of diphenylurea and dibenzylurea, respectively. An expanded substrate scope including the electron-rich and electron-deficient anilines, primary aliphatic amines, secondary amines was also established. This work offers a straightforward, step economic, and green methodology for the efficient synthesis of valuable ureas.
- Liu, Shujuan,Dai, Xingchao,Wang, Hongli,Shi, Feng
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supporting information
p. 4040 - 4045
(2019/08/07)
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- Iron-catalyzed urea synthesis: Dehydrogenative coupling of methanol and amines
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Substituted ureas have numerous applications but their synthesis typically requires the use of highly toxic starting materials. Herein we describe the first base-metal catalyst for the selective synthesis of symmetric ureas via the dehydrogenative coupling of methanol with primary amines. Using a pincer supported iron catalyst, a range of ureas was generated with isolated yields of up to 80% (corresponding to a catalytic turnover of up to 160) and with H2 as the sole byproduct. Mechanistic studies indicate a stepwise pathway beginning with methanol dehydrogenation to give formaldehyde, which is trapped by amine to afford a formamide. The formamide is then dehydrogenated to produce a transient isocyanate, which reacts with another equivalent of amine to form a urea. These mechanistic insights enabled the development of an iron-catalyzed method for the synthesis of unsymmetric ureas from amides and amines.
- Lane, Elizabeth M.,Hazari, Nilay,Bernskoetter, Wesley H.
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p. 4003 - 4008
(2018/05/04)
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- Organic ligand-free carbonylation reactions with unsupported bulk Pd as catalyst
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Herein, surprising results for bulk Pd-catalyzed carbonylation reactions are presented. Three types of carbonylation reactions can be realized efficiently under organic ligand-free conditions, namely, hydroaminocarbonylation of olefins, aminocarbonylation of aryl iodides and oxidative carbonylation of amines, which almost cover all the known mechanisms in carbonylation reactions. Notably, the bulk Pd catalyst system exhibited better catalytic activity than the classical homogeneous PdCl2/(2-OMePh)3P catalyst system. This study will create a momentous and new field of green carbonylation reactions.
- Liu, Shujuan,Wang, Hongli,Dai, Xingchao,Shi, Feng
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supporting information
p. 3457 - 3462
(2018/08/06)
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- One-Pot Synthesis of Disubstituted Urea from Carbon Dioxide, Propylene Oxide, and Amines Catalyzed by Imidazolium-Tetraiodoindate
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In this article, synthesis of 1,3-disubstituted urea (DSU) from three component reagent systems comprising amine, carbon dioxide, and propylene oxide is described. DSU is synthesized in the presence of a variety of ionic liquids (ILs) with/without promoters. Among used ILs, 1-butyl-3-methylimidazolium tetraiodoindateIII (represented as [Bmim][InI4]) is found to give the highest DSU product. A serious experiment clearly indicates that the tetraiodoindate anion plays an important role for the selective production of the DSU. Based on the in situ infrared spectroscopic studies, a plausible reaction mechanism for producing dicyclohexylurea from cyclohexylamine is proposed. The synthesis and characterization of [Bmim][InI4] are given in details. Moreover, the effect of reaction variables such as time, temperature, pressure, and the molar ratio of substrate to catalyst is also studied.
- Son, Guang Meang,Truong, Cong Chien,Mishra, Dinesh Kumar,Mishra, Vivek,Kim, Yong Jin
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p. 174 - 183
(2018/01/27)
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- Ruthenium-Catalyzed Urea Synthesis by N-H Activation of Amines
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Activation of the N-H bond of amines by a ruthenium pincer complex operating via amine-amide metal-ligand cooperation is demonstrated. Catalytic formyl C-H activation of N,N-dimethylformamide (DMF) is observed in situ, which resulted in the formation of CO and dimethylamine. The scope of this new mode of bond activation is extended to the synthesis of urea derivatives from amines using DMF as a carbon monoxide (CO) surrogate. This catalytic protocol allows the synthesis of simple and functionalized urea derivatives with liberation of hydrogen, devoid of any stoichiometric activating reagents, and avoids the direct use of fatal CO. The catalytic carbonylation occurred at low temperature to provide the formamide; a formamide intermediate was isolated. The consecutive addition of different amines provided unsymmetrical urea compounds. The reactions are proposed to proceed via N-H activation of amines followed by CO insertion from DMF and with liberation of dihydrogen.
- Krishnakumar, Varadhan,Chatterjee, Basujit,Gunanathan, Chidambaram
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supporting information
p. 7278 - 7284
(2017/06/23)
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- Well-Defined Cesium Benzotriazolide as an Active Catalyst for Generating Disubstituted Ureas from Carbon Dioxide and Amines
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The reaction of alkali metal carbonates with various azole compounds produced a new series of alkali metal azolides, and they were applied as active catalysts for the production of disubstituted ureas from the carboxylation of various amines with CO2. Among them, cesium benzotriazolide (Cs[BTd]) was found to be the most active for the carboxylation reaction and was structurally characterized by single-crystal X-ray diffraction. The crystal structure of highly hygroscopic Cs[BTd] was found to be [BTA]???Cs[BTd], which explains why it is a water-tolerant active species for this carboxylation reaction, leading to a maximum turnover frequency of 344 h?1 as well as high recyclability even after five successive runs.
- Truong, Cong Chien,Kim, Jin,Lee, Yunho,Kim, Yong Jin
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p. 247 - 252
(2017/02/05)
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- CO-use CO2 Method for synthesizing N, N - dialkyl oxalate
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The invention provides a method for synthesizing N,N-dialkyl oxamide by using CO2. According to the method, in an organic or inorganic solvent, one-step synthetic reaction is performed on the CO2 and organic amine to synthesize the N,N-dialkyl oxamide, with N,N-dialkyl urea and water as byproducts, in the presence of a certain catalyst and under a certain reaction condition that the reaction pressure is 10-80atm and the reaction temperature is 100-200 DEG C. The invention discloses the method for synthesizing the N,N-dialkyl oxamide by using the CO2. According to the method, a valuable and toxic metal catalyst and a toxic and explosive gas in the prior art are not used, and reactants, products, and added components in a system are safe and environment-friendly; the yield is considerable; technically, an improvement room exists; a safe and environment-friendly new method is provided for preparing the N,N-dialkyl oxamide.
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Paragraph 0047; 0048; 0049; 0050; 0051
(2016/11/17)
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- Co(acac)3/BMMImCl as a base-free catalyst system for clean syntheses of N,N′-disubstituted ureas from amines and CO2
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A base-free catalyst system Co(acac)3/BMMImCl was developed for the carbonylation of amines with CO2. 45%2-81% isolated yields for N,N-dialkylureas and 6%2-23% isolated yields for N,N-diarylureas were obtained. The catalyst system was recovered and reused without significant loss in activity. In this catalyst system, the base catalyst and chemical dehydrant were efficiently avoided. Different reaction conditions were also discussed and a postulated mechanism was proposed.
- Li, Jian,Guo, Xiaoguang,Wang, Liguo,Ma, Xiangyuan,Zhang, Qinghua,Shi, Feng,Deng, Youquan
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experimental part
p. 1534 - 1540
(2010/11/04)
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- Synthesis of 1,3-disubstituted symmetrical/unsymmetrical ureas via Cs2CO3-catalyzed transamination of ethylene carbonate and primary amines
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Cs2CO3-catalyzed transamination of primary amines and ethylene carbonate proceeds to form 1,3-disubstituted symmetrical/unsymmetrical ureas in excellent yields. The effect of different reaction parameters such as influences of bases, temperature, and reaction time were investigated for the title reaction.
- Jagtap, Sachin R.,Patil, Yogesh P.,Panda, Anil G.,Bhanage, Bhalchandra M.
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experimental part
p. 2093 - 2100
(2009/10/17)
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- Solvent-free synthesis of urea derivatives from primary amines and sulfur under carbon monoxide and oxygen at atmospheric pressure
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A solvent-free carbonylation and oxidation system aimed at green and sustainable chemistry was developed. With these reactions, an environmentally benign synthesis of urea derivatives could be carried out in good to excellent yields from primary amines and sulfur at ambient pressure of carbon monoxide and oxygen. For example, N,N′-dioctylurea was prepared in 99% yield from two equivalents octylamine and one equivalent sulfur in the presence of carbon monoxide (1 atm) at 80°C and oxygen (1 atm) at room temperature, in the complete absence of solvent. Georg Thieme Verlag Stuttgart.
- Mizuno, Takumi,Mihara, Masatoshi,Nakai, Takeo,Iwai, Toshiyuki,Ito, Takatoshi
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p. 3135 - 3140
(2008/04/03)
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- Practical synthesis of urea derivatives from primary amines, carbon monoxide, sulfur, and oxygen under mild conditions
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A new and facile synthetic method for urea derivatives was developed under mild conditions, and contrasts with conventional preparation methods that need highly toxic reagents (phosgene) or severe reaction conditions. In our reaction system, N,N-dimethylformamide or dimethyl sulfoxide as solvent strongly accelerated the carbonylation of primary amines with sulfur under carbon monoxide (1 atm) at 20 °C to give the corresponding thiocarbamate salts. These salts were readily oxidized by molecular oxygen under similarly mild conditions to afford urea derivatives in good to excellent yields. This urea synthesis could also be applied to a new synthesis of aromatic ureas by use of 1,8-diazabicyclo[5.4.0]undec-7-ene in N,N-dimethylformamide. Georg Thieme Verlag Stuttgart.
- Mizuno, Takumi,Mihara, Masatoshi,Iwai, Toshiyuki,Ito, Takatoshi,Ishino, Yoshio
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p. 2825 - 2830
(2008/02/05)
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- OXIDATIVE CARBONYLATION OF ALKYLAMINES, COMBINED WITH REDUCTION OF NITROBENZENES
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A study has been made of oxidative carbonylation of monoalkylamines in the course of reduction of nitrobenzenes.
- Manov-Yuvenskii, V. I.
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p. 1612 - 1618
(2007/10/03)
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- Reactions of (η-methylcyclopentadienyl)manganese tricarbonyl with primary amines
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(η-CH3C5H4)Mn(CO)3 reacts with RNH2 (R = n-C4H9, sec-C4H9, n-C5H11, n-C6H13, cyclo-C6H11, n-C7H15, n-C8H17, n-C9H19 or C6H5CH2) to give corresponding sym-dialkylureas when a 1:2 molar mixture of the two reactants is irradiated with UV light for 100-250 h.The complexes (η-CH3C5H4)Mn(CO)2(CONHR)(H) were isolated for R = n-C4H9, n-C6H13 and cyclo-C6H11.
- Srivastava, S.C.,Shrimal, A.K.,Srivastava, Amar
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