- Di-tert-butyl peroxide (DTBP)-mediated synthesis of symmetrical N,N′-disubstituted urea/thiourea motifs from isothiocyanates in water
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ABATRACT: A direct approach to N,N′-disubstituted urea/thiourea from the self-condensation reactions of isothiocyanates in water has been developed. This access tolerated a wide range of functional groups on the aromatic ring, providing a practical and environment-friendly process to N,N′-disubstituted urea/thiourea in moderate to excellent yields from safe and easily available starting materials. A plausible mechanism of the desulfurization self-condensation reaction for urea was also proposed and the role of di-tert-butyl peroxide (DTBP) and copper catalyst in the present strategy was demonstrated with the help of ESI mass spectrometry of intermediate studies.
- Chen, Ling,Dong, Yibo,Wu, Yangjie,Yang, Jinchen,Zhang, Jinli
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supporting information
(2021/12/01)
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- Investigation of active sites using solid state 27Al and 31P MAS NMR in ceramic amorphous aluminophosphate materials prepared from different potassium salts of phosphate for the synthesis of diphenyl urea derivatives
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Ceramic amorphous aluminophosphate (CAmAlP) catalysts were prepared by precipitation method using different phosphate salts of potassium such as KH2PO4, K4P2O7 and K2HPO4 as well as H3PO4. The prepared materials were characterized by PXRD, FT-IR, XPS, SEM, BET Surface area, NH3-TPD, 27Al NMR and 31P NMR analytical methods. The catalytic activity of the materials was checked in the synthesis of diphenyl urea (DPU) from aniline and diethyl carbonate, under refluxing conditions. Further, the general application of the catalysts was tested using various substituted anilines. The recyclability of the catalysts was also studied. Uncertainties in percentage yields were calculated to check the reproducible surface properties. The P-XRD, BET Surface area and NH3-TPD results indicated that the materials were amorphous with mesoporous texture, surface areas and acidities in the range 200–260 m2/g and 0.4–0.7 mmol/g respectively. 27Al NMR studies revealed that Al is present in three different coordination states such as tetrahedral, pentagonal and octahedral. The relative percentages of these Al sites depends on the type of the potassium precursor phosphate salt used. Both tetrahedral and pentagonal Al sites in conjunction with each other represented catalytically active sites. An increase in the pentagonal sites contributed to additional increments to the catalytic activity of CAmAlP. The catalyst prepared from KH2PO4 was found to be the best and demonstrated 96% DPU yield.
- Harish,Kathyayini,Baby, Bindhu,Nagaraju
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- Palladium-Catalyzed Aerobic Oxidative Carbonylation of Amines Enables the Synthesis of Unsymmetrical N,N′-Disubstituted Ureas
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A ligand-free palladium-catalyzed aerobic oxidative carbonylation of amines for the synthesis of ureas, particular unsymmetrically N,N′-disubstituted ureas, which cannot be accessed by any other palladium-catalyzed oxidative carbonylation of amines to date, is presented. An array of symmetrical and unsymmetrical ureas were straightforwardly synthesized by using inexpensive, readily available, stable, and safe amines with good to excellent yields under a pressure of 1 atm. This novel method employs oxygen as the sole oxidant and offers an attractive alternative to transition-metal-based oxidant systems.
- Zeng, Honglan,Du, Hongyan,Gong, Xu,Zhang, Jie,Han, Wei
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p. 1223 - 1226
(2021/06/02)
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- Amide-assisted rearrangement of hydroxyarylformimidoyl chloride to diarylurea
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A novel amide-assisted rearrangement reaction of hydroxybenzimidoyl chloride has been established for the efficient synthesis of 1,3-diphenylurea derivatives. A variety of electronically and sterically different 1,3-diphenylurea derivatives can be obtained in good to excellent yields, and a proposed reaction mechanism is also presented.
- Jin, Yi,Liu, Xiaoyu,Song, Xizhong,Yu, Wei
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supporting information
(2021/11/11)
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- An Improved Synthesis of Urea Derivatives from N -Acylbenzotriazole via Curtius Rearrangement
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The good leaving tendency of the benzotriazole moiety has been exploited for the synthesis of symmetric, unsymmetric, N -acyl, and cyclic ureas in good yields from N -acylbenzotriazoles by treating the latter with various amines in the presence of TMSN 3 /Et 3 N in a sealed tube. The salient features of the devised protocol includes the high-yield, mild, metal-free, one-pot reaction conditions, and short reaction time. Furthermore, in many cases, no column chromatography is required for the purification.
- Agrahari, Anand K.,Singh, Anoop S.,Singh, Sumit K.,Tiwari, Vinod K.,Yadav, Mangal S.
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p. 3443 - 3450
(2019/09/07)
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- N,N'-disubstituted urea compound and synthesis method thereof
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The invention discloses an N,N'-disubstituted urea compound and a preparation method thereof. N-alkyl acyloxy amide is taken as a raw material and a dichloro(p-cymene)ruthenium(II) dimer complex is taken as a catalyst for carrying out a reaction in an organic solvent under the presence of silver acetate, and the N,N'-disubstituted urea compound is prepared. Compared with the prior art, the methodhas the following advantages that only an amide derivative is taken as a raw material, reaction conditions are mild, the application range of substrates is wide, operation is simple and convenient, the catalyst is low in price, and selectivity of the product is high.
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Paragraph 0042-0045
(2019/04/10)
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- Hydrogen-Bonded Homoleptic Fluoride-Diarylurea Complexes: Structure, Reactivity, and Coordinating Power
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Hydrogen bonding with fluoride is a key interaction encountered when analyzing the mode of action of 5′-fluoro-5′-deoxyadenosine synthase, the only known enzyme capable of catalyzing the formation of a C-F bond from F-. Further understanding of the effect of hydrogen bonding on the structure and reactivity of complexed fluoride is therefore important for catalysis and numerous other applications, such as anion supramolecular chemistry. Herein we disclose a detailed study examining the structure of 18 novel urea-fluoride complexes in the solid state, by X-ray and neutron diffraction, and in solution phase and explore the reactivity of these complexes as a fluoride source in SN2 chemistry. Experimental data show that the structure, coordination strength, and reactivity of the urea-fluoride complexes are tunable by modifying substituents on the urea receptor. Hammett analysis of aryl groups on the urea indicates that fluoride binding is dependent on σp and σm parameters with stronger binding being observed for electron-deficient urea ligands. For the first time, defined urea-fluoride complexes are used as fluoride-binding reagents for the nucleophilic substitution of a model alkyl bromide. The reaction is slower in comparison with known alcohol-fluoride complexes, but SN2 is largely favored over E2, at a ratio surpassing all hydrogen-bonded complexes documented in the literature for the model alkyl bromide employed. Increased second-order rate constants at higher dilution support the hypothesis that the reactive species is a 1:1 urea-fluoride complex of type [UF]- (U = urea) resulting from partial dissociation of the parent compound [U2F]-. The dissociation processes can be quantified through a combination of UV and NMR assays, including DOSY and HOESY analyses that illuminate the complexation state and H-bonding in solution.
- Pfeifer, Lukas,Engle, Keary M.,Pidgeon, George W.,Sparkes, Hazel A.,Thompson, Amber L.,Brown, John M.,Gouverneur, Véronique
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supporting information
p. 13314 - 13325
(2016/10/22)
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- Method for catalytically synthesizing N, N'-disubstituted urea derivative and imidazole derivative
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The present invention relates to a green and efficient method for preparing an N, N'-disubstituted urea derivative and an imidazole derivative. The method for preparing the N, N'-disubstituted urea derivative by condensation of an aromatic amine with a carbonate ester comprises: by using ionic liquid loaded magnetic nanoparticles as a catalyst, at the temperature of 60-100 DEG C, and at a normal pressure, and in a condition of solvent-free, performing a condensing reaction on the aromatic amine and the carbonate ester for 8-14 hours to obtaina corresponding N, N'-disubstituted urea derivative; by using a magnetic nanoparticle-loaded ionic liquid as a catalyst and by using ethanol as a solvent, performing Michael addition reaction of a substituted imidazole and an electron-deficient olefin for 1-5 hours at the temperature of 10-50 DEG C and at a normal pressure to obtain a corresponding imidazole derivative, wherein the catalyst is as shown in the specification. Experiments verify that after the reaction is completed, the catalyst is recycled simply through an external magnetic field and can be repeatedly used for many times, but the activity is not obviously reduced. The catalytic system is simple in operation and high in yield, and the reusability is good, so that the method has a good industrial prospect.
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Paragraph 0044; 0045; 0046; 0047
(2016/10/17)
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- An efficient one-pot synthesis of: N, N ′-disubstituted ureas and carbamates from N -acylbenzotriazoles
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A facile and high-yielding one-pot synthesis of carbamates and N,N′-disubstituted symmetrical ureas from N-acylbenzotriazoles has been devised. It is believed that, the intermediate acyl-azide undergo Curtius rearrangement and in different solvents gives different products i.e. carbamates in alcohols and N,N′-disubstituted symmetrical urea in THF.
- Singh, Anoop S.,Kumar, Dhananjay,Mishra, Nidhi,Tiwari, Vinod K.
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p. 84512 - 84522
(2016/10/12)
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- A simple and efficient synthesis of diaryl ureas with reduction of the intermediate isocyanate by triethylamine
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Thirty symmetrical diaryl urea derivatives were synthesised in moderate to excellent yields from arylamine and triphosgene with triethylamine as a reducing agent for the intermediate, isocyanate. It was significant that part of the products could be collected in almost quantitative yield without column chromatography. The procedure under mild reaction conditions was tolerant of a wide range of functional groups. The structures of the compounds were determined by NMR, MS and X-ray crystallographic analyses.
- Zhou, Shuguang,Yao, Ting,Yi, Jicheng,Li, Dashuai,Xiong, Jing
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p. 315 - 319
(2013/07/27)
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- Synthesis of unsymmetrical 2-pyridyl ureas via selenium-catalyzed oxidative carbonylation of 2-aminopyridine with aromatic amines
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A simple, one-pot, phosgene-free approach to a series of unsymmetrical 2-pyridyl ureas starting from 2-aminopyridine and various aromatic amines is reported for the first time. The procedure employs inexpensive selenium as the catalyst, and carbon monoxide (instead of phosgene) as the carbonyl reagent. The products are obtained in moderate to good yields via selenium-catalyzed oxidative cross-carbonylation of the substrate amines in the presence of oxygen. The selenium functions as a phase-transfer catalyst and can be recovered easily and reused without any significant degradation of its catalytic activity.
- Zhang, Xiaopeng,Li, Desheng,Ma, Xueji,Wang, Yan,Zhang, Guisheng
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p. 1357 - 1363
(2013/07/05)
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- Palladium-catalyzed carbonylation of amines: Switchable approaches to carbamates and N,N′-disubstituted ureas
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Switchable access to carbamates and ureas has been developed by solvent control palladium-catalyzed carbonylation of aromatic amines under an atmosphere of carbon monoxide. A variety of N-phenylcarbamates and N,N′- diphenylureas was easily synthesized in good to excellent yields from readily available aromatic amines under mild conditions. Copyright
- Guan, Zheng-Hui,Lei, Hao,Chen, Ming,Ren, Zhi-Hui,Bai, Yinjuan,Wang, Yao-Yu
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supporting information; experimental part
p. 489 - 496
(2012/04/04)
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- Palladium-catalyzed synthesis of symmetrical urea derivatives by oxidative carbonylation of primary amines in carbon dioxide medium
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An efficient palladium-catalyzed synthesis of symmetrically disubstituted ureas via oxidative carbonylation of primary amines is described. The reactions are carried out in the presence of a large excess of carbon dioxide as reaction medium or under solvent-free conditions. The adopted catalyst such as potassium tetraiodopalladate, stable and easy to prepare, allows the use of air as a cheap oxidizing agent. The reactions yield urea and water as the only by-product and proceed with high efficiency with aliphatic and aromatic amines as well. While with primary aliphatic amines, no significant improvement on reactivity is observed when carbon dioxide is used as a solvent, in comparison with the conventional ones, a remarkable high efficiency is obtained with aromatic amines, which shows a dramatic increase in the performance of the catalyst, in terms of turnover number (TON), the highest known so far for this kind of process. Reactions take place in two-phase systems consisting of a homogeneous liquid phase formed by the CO2 expanded amine solution containing the catalyst and a supercritical phase of CO2, CO, O2, and N2.
- Ca', Nicola Della,Bottarelli, Paolo,Dibenedetto, Angela,Aresta, Michele,Gabriele, Bartolo,Salerno, Giuseppe,Costa, Mirco
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experimental part
p. 120 - 127
(2011/09/16)
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- One-pot synthesis of symmetrical 1,3-diarylureas or substituted benzamides directly from benzylic primary alcohols and effective oxidation of secondary alcohols to ketones using phenyliodine diacetate in combination with sodium azide
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Benzylic primary alcohols can be directly converted into symmetrical 1,3-diarylureas or substituted benzamides via an one-pot oxidative reaction using the combined reagent of phenyliodine diacetate and sodium azide. This new reaction constitutes a step-economical way to prepare symmetric 1,3-diarylureas or substituted benzamides depending upon the substituents on the phenyl rings of starting alcohols. The sodium acetate generated in situ from the ligand exchange between phenyliodine diacetate and sodium azide plays the pivotal role in the formation of 1,3-diarylureas. In addition, it is also found that various secondary alcohols can be readily oxidized to their corresponding ketones in excellent yields using the same reagent system of phenyliodine diacetate and sodium azide. Generally, secondary alcohols are preferentially oxidized to the corresponding ketones in the presence of primary ones with the limited amounts of phenyliodine diacetate and sodium azide.
- Li, Xiao-Qiang,Wang, Wei-Kun,Han, Yi-Xin,Zhang, Chi
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experimental part
p. 2588 - 2598
(2010/12/25)
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- Microwave induced improved synthesis of monoaryl thiocarbamides, 1,3-diarylthiocarbamides, 1,3-diarylcarbamides and monoaryl-2,4-dithiobiurets
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The 1-arylthiocarbamides (3), 1, 3-diarylthiocarbamides (6), 1,3-diarylcarbamides (7) and 1-aryl-2,4-dithiobiurets (11) have been synthesized by the microwave induced heating of respective reactants for about 30-60 s in solvent free condition. Reaction yields are higher with reduced time, period and without the use of any solvent.
- Uberhande,Thakare,Berad
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experimental part
p. 1137 - 1141
(2011/05/05)
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- Efficient method of synthesis of N,N′-disubstituted ureas/thioureas by a Zinc chloride catalyzed thermal reaction
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Symmetrically N,N'-disubstituted ureas/thioureas were synthesized by heating amines or phenyl hydrazine and urea/thiourea on a preheated hot plate at 80-85C under solvent-free conditions in the presence of a catalytic amount of ZnCl2 as a catalyst. The protocol has the advantages of not using toxic phosgene and other hazardous substrates or organic solvents. Increased reaction rate, good yield, and a simple workup procedure are involved.
- Pasha,Madhusudana Reddy
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experimental part
p. 2928 - 2934
(2009/12/03)
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- Efficient synthesis of N,N′-disubstituted ureas/thioureas catalyzed by iodine
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Iodine is an efficient catalyst for the synthesis of symmetrically N,N′-disubstituted ureas/thioureas by heating respective amines or phenyl hydrazine and urea/thiourea on a preheated hot plate at 90-95°C, under solvent-free conditions. The yields are excellent, and the reactions go to complete within 5-10 min. Copyright Taylor & Francis Group, LLC.
- Pasha,Jayashankara
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p. 1787 - 1793
(2007/10/03)
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- A rapid microwave assisted synthesis of N, N′-diarylureas under solvent-free condition
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A novel microwave assisted phosgene-free synthesis of N,N′- diarylureas under solvent-free conditions has been described.
- Sarveswari,Raja
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p. 546 - 547
(2007/10/03)
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- Copper catalyzed arylation of urea
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An efficient copper catalyzed amidation of aryl iodides with urea is described. This method is milder than the palladium catalyzed arylation and avoids the use of toxic phosphine ligands.
- Nandakumar, Mecheril V.
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p. 1989 - 1990
(2007/10/03)
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- Variation of xanthene-based bidentate ligands in the palladium-catalyzed arylation of ureas
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A series of xanthene-based bidentate ligands containing various substituents on diphenylphosphino groups were synthesized and tested in the palladium-catalyzed arylation reaction of urea with unactivated aryl bromides. It was found that both steric and electronic properties of the ligands have a pronounced effect on the yields and ratios of the products. Arylation of urea and phenylurea with unactivated aryl bromides in the presence of Pd2dba3·CHCl3/3,5-(CF3) 2Xantphos and Cs2CO3 as base in dioxane at 100°C gave the corresponding N,N′-diarylureas in 62-98% yields.
- Sergeev, Alexey G.,Artamkina, Galina A.,Beletskaya, Irina P.
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p. 4719 - 4723
(2007/10/03)
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- Variation of xantphos-based ligands in the palladium-catalyzed reaction of aryl halides with ureas
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A series of Xantphos-based ligands containing various substituents in the diphenylphosphino groups were synthesized, and their effect on the product yield and ratio in the palladium-catalyzed arylation of ureas with nonactivated aryl halides was studied. The arylation of urea and phenylurea in the presence of Pd2(dba)3-CHCl3, 3,5-(CF3) 2Xantphos, and Cs2CO3 in dioxane at 100°C gave the corresponding N,N′-diarylureas in 62-98% yield.
- Sergeev,Artamkina,Beletskaya
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p. 1741 - 1752
(2007/10/03)
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- Organic-fluorous phase switches: A fluorous amine scavenger for purification in solution phase parallel synthesis
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The synthesis of the fluorous amine scavenger [(C6F13CH2CH2)3SSiCH 2CH2CH2]2NH and its successful application in the automated solution phase parallel synthesis of a urea library are described. Ureas were made by robotic synthesis from organic amines and excess isocyanates. The amine scavenger reacts with excess isocyanate, and the fluorous tag serves to solubilize the resulting adduct in the fluorous phase so it can be removed by fluorous-organic extraction. Organic urea products are isolated in high yields and purities after liquid - liquid extraction. Preliminary biological evaluation shows that several of the ureas have ion channel modulation abilities. In contrast to polymer and ionic quenching methods, the fluorous quench works whether the product is soluble or insoluble in the reaction medium, and ionizable functional groups are tolerated in the products.
- Linclau, Bruno,Sing, Ashvani K.,Curran, Dennis P.
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p. 2835 - 2842
(2007/10/03)
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- Reaction of aromatic amines and ethyl acetoacetate promoted by zeolite HSZ-360. Phosgene-free synthesis of symmetric diphenylureas
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Reaction of aromatic amines 1 with ethyl acetoacetate 2 in the presence of the commercially available acid zeolite HSZ-360 gives symmetric diphenylureas 3 in good yields and excellent selectivities.
- Bigi, Franca,Maggi, Raimondo,Sartori, Giovanni,Zambonin, Elena
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p. 513 - 514
(2007/10/03)
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- NEW ROUTE FOR THE SYNTHESIS OF SYMMETRICAL DIARYLUREA
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Several esters of aryl carbamic acid were thermally dissociated into symmetrically diarylurea in high yields.The electronic effect and position of the substitution in the aryl groups as well as the role of the alkyl groups on the thermal reaction are discussed.
- Hassan, Alaa A.,Mourad, Aboul-Fetouh E.
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p. 397 - 404
(2007/10/02)
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- A new route for the synthesis of symmetrical diarylureas
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Several esters of arylcarbamic acid have been thermally dissociated into symmetrical diarylureas in high yields.The electronic effect and position of substitution in the aryl groups as well as the role of alkyl groups on thermal reaction have been discussed.
- Hassan, Alaa A,Mourad, Aboul-fetouh E
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p. 277 - 279
(2007/10/02)
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- Oxadiazole Condensed Ring Systems, II : Synthesis of New 2-Aryl-1,3,4-oxadiazolo-s-triazine-5,7(6H)-diones
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The syntheses of 1,3,4-oxadiazolo-s-triazine-5,7(6H)-diones 4 through the condensation of 2-amino-5-aryl-1,3,4-oxadiazoles 1 with ethoxycarbonyl isocyanate 2 is described.Methylation of 4b with trimethyl phosphate yielded the N-methyl derivative 5.
- Hassan, Ahmed M. M.,Badawey, El-Sayed A. M.
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- Hydrogen bond directed cocrystallization and molecular recognition properties of diarylureas
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The hydrogen bond directed molecular recognition properties of a series of diarylurea (DAU) compounds have been studied using cocrystallization to probe hydrogen bond donor and acceptor selectivity of the host and guest molecules. Diarylureas with meta-substituted electron-withdrawing groups on the aryl rings are capable of forming cocrystal complexes with a wide variety of hydrogen bond acceptors. One particular DAU, 1,3-bis(m-nitrophenyl)urea, behaves primarily as a proton donor, one of the few organic molecules known to have this property. Its hydrogen bond accepting ability is drastically reduced, possibly because of two very weak CH?O interactions occurring in response to the presence of guest acceptor molecules and effectively negating the powerful proton-accepting ability of the urea carbonyl group. Only DAU compounds with meta-substituted electron-withdrawing groups have this property. The crystal structures of four DAU compounds and six of their cocrystal structures are reported. In addition, 19 other DAU cocrystals were prepared and characterized by chemical and spectroscopic means, and their hydrogen bond patterns were assigned based on spectroscopic analogies to those with known crystal structures. From this data hydrogen bond rules for diarylureas have been derived for use in predicting hydrogen bond patterns in related structures.
- Etter, Margaret C.,Urba?czyk-Lipkowska, Zofia,Zia-Ebrahimi, Mohammad,Panunto, Thomas W.
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p. 8415 - 8426
(2007/10/02)
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- Process for the preparation of herbicidally active phenyl carbamates
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Herbicidally active substituted phenyl carbamates I STR1 in which R1 represents a C1 -C6 alkyl group, a C3 -C6 cycloalkyl group or an aryl group, which aryl group may be substituted by a halogen atom and/or a C1 -C6 alkyl group and/or a trifluoromethyl group, and R2 represents a C1 -C6 alkyl, C2 -C6 alkenyl or C2 -C6 alkynyl group that may be substituted by a terminal halogen atom, are prepared by reacting N-hydroxyphenyl carbamates II STR2 with either isocyanates R1 --N=C=O or amino chlorides R1 --NH--COCl in an aqueous medium thus avoiding the use of organic solvents. The end product I may be extracted from the aqueous slurry into a water-immiscible solvent. The N-hydroxyphenyl carbamates II can be prepared by reacting 3-aminophenol with chloroformates in an aqueous medium, and the resulting product may be reacted in situ, without isolation, with isocyanates, in the same reaction vessel. Stabilized herbicidal compositions containing compounds I may be prepared by suspending the compounds I in a liquid phase comprising one or more oily components and one or more surfactants.
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- Nucleophilic Substitutions at Carbonic Acid Derivatives. XX. Aminolysis of Bis(trichlormethyl)carbonate
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The rate constants for the two steps of the reaction of bis(trichlormethyl)carbonate with substituted anilines have been determinated by conductivity measurements.The first relatively fast step of the reaction is the nucleophilic attack of the amine to the bis(trichloromethyl)carbonate leading to trichloromethylurethane through a six or four centers transition state in wich the carbon-nitrogen bond is formed parallel with the transfer of the proton.In this reaction a phosgene molecule is also produced, which reacts very fast with amine to form a N,N'-diarylurea.The s econd, much slower step, is the nucleophilic attack of the amine to the trichloromethylurethane.Through a similar transition state in which the proton transfer has even a higher importance, a N,N'-disubstituted urea and an other molecule of phosgene are formed.
- Cotarca, Livius,Bacaloglu, R.,Csunderlik, C.,Marcu, N.,Tarnaveanu, A.
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p. 1052 - 1062
(2007/10/02)
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- Reaction of Nitromethane with Aryl Isocyanates in the Presence of Triethylamine. A Formation of 1,3-Diaryl-5-(hydroxyimino)imidazolidine-2,4-diones
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1,3-Diaryl-5-(hydroxyimino)imidazolidine-2,4-diones were obtained from the reactions of nitromethane with several aryl isocyanates in the presence of a trace amount of triethylamine and their structures were established from spectroscopic evidence and their chemical behavior.
- Shimizu, Tomio,Hayashi, Yoshiyuki,Teramura, Kazuhiro
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p. 2038 - 2040
(2007/10/02)
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- THERMAL DECOMPOSITION OF SUBSTITUTED UREAS
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The thermal dissociation of N,N'-diaryl- and N,N-dimethyl-N'-aryl-ureas was investigated under isothermal conditions in absence of solvent.In the case of N,N-dimethyl-N'-arylureas enthalpies of reaction were determined, and their relation to Hammett ? constants was shown.
- Chimishkyan, A. L.,Svetlova, L. P.,Leonova, T. V.,Gluyaev, N. D.
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p. 1317 - 1320
(2007/10/02)
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- SUBSTITUENT EFFECTS ON HYDROLYTIC STABILITY AND HERBICIDAL ACTIVITY OF 3-ARYLIMIDAZOLIDINE-2,4-DIONES
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Twenty-one derivatives of imidazolidine-2,4-dione have been prepared by reactions of substituted amino acids with aryl isocyanates in aqueous medium.Pre- and post-emergent herbicidal activities of all the compounds have been tested, and stability of five derivatives has been followed in aqueous medium within the pH range from 7.6 to 13.0.The highest pre-emergent herbicidal activity has been found with the derivatives XI-XVI which inhibit the growth of most indicator plants at the doses of 1.6 kg/ha.The derivatives studied are relatively stable in aqueous medium, the hydrolysis half-life of the compound XI being 9 days at pH 8.
- Cegan, Alexandr,Vecera, Miroslav
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p. 1521 - 1528
(2007/10/02)
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- DIRECT SYNTHESIS OF N-ARYL BENZAMIDES BY REDUCTIVE CARBONYLATION OF NITROARENES CATALYZED BY RHODIUM CARBONYLS IN BENZENE
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The reactions of nitroarenes, carbon monoxide, and benzene in the presence of Rh4(CO)12 or Rh6(CO)16 give N-aryl benzamides via the reductive carbonylation of nitroarenes and subsequent addition of benzene to the resulting aryl isocyanates.
- Mise, Takaya,Hong, Pangbu,Yamazaki, Hiroshi
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p. 439 - 440
(2007/10/02)
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