- Isocyanates From Primary Amines and Carbon Dioxide: 'Dehydration' of Carbamate Anions
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Carbamate anions, derived from primary amines CO2 and an added base (e.g.NEt3), undergo rapid reaction with electrophilic 'dehydrating agents' (e.g.POCl3, P4O10) to give the corresponding isocyanates in excellent yields.
- Waldman, Thomas E.,McGhee, William D.
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- Method for preparing p-phenylene diisocyanate by non-phosgene method
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The invention discloses a method for preparing p-phenylene diisocyanate by a non-phosgene method, one of the following methods is selected: (a) taking N, N''-(1, 4-phenylene) bis (N', N'-dialkyl) urea and protonic acid as raw materials, and carrying out protonation and pyrolysis to obtain p-phenylene diisocyanate; and (b) taking p-phenylenediamine, dialkyl carbamoyl chloride and an acid-binding agent as raw materials, carrying out nucleophilic substitution reaction to generate N, N''-(1, 4-phenylene) bis (N', N '-dialkyl) urea and ammonium hydrochloride corresponding to the acid-binding agent in situ, and then carrying out protonation and pyrolysis to obtain the p-phenylene diisocyanate. According to the preparation method, p-phenylene diisocyanate is synthesized in one step or continuously by using an intermittent tank reactor or a micro-channel continuous flow reactor under the action of protonic acid. The intermittent and continuous preparation process of the non-phosgene method has the advantages that the reaction time is short, the product is easy to separate, a hydrogen chloride byproduct is not generated and the like, the purity of the product is as high as 98%, and the yield is as high as 97%.
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- FLOW CHEMISTRY SYNTHESIS OF ISOCYANATES
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The disclosure provides, inter alia, safe and environmentally-friendly methods, such as flow chemistry, to synthesize isocyanates, such as methylene diphenyl diisocyanate, toluene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and tetramethylxylene diisocyanate.
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Paragraph 0175; 0185-0187; 0228; 0234-0239
(2021/06/22)
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- Method for preparing low-chlorinated impurity content isocyanate based on salt formation light gasification (by machine translation)
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The invention provides a method for preparing low-chlorinated impurity content isocyanate based on a salt-formation light gasification method. The proportion of the salt particle size distribution obtained by the salt formation reaction in the average particle size ±30% range is 70% or more, the average residence time without stirring is less than 60 min, and the product obtained by the method has lower chlorinated impurity content. (by machine translation)
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Paragraph 0066-0067; 0080-0081
(2020/10/14)
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- Preparation method of p-phenyl diisocyanate
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The invention provides a preparation method of p-phenylene diisocyanate. The preparation method comprises the following steps that: p-phenylenediamine is dissolved in a low-boiling-point solvent undernormal temperature to 65 DEG C, so that a p-phenylenediamine solution can be prepared; di-(trichloromethyl) carbonate is dissolved in a high-boiling-point solvent, so that a di-(trichloromethyl) carbonate solution can be prepared; the p-phenylenediamine solution and the di-(trichloromethyl) carbonate solution are mixed, the mixed solution is subject to a reaction; and after the mixed solution issubjected to three reaction stages of cold light (from the normal temperature to 40 DEG C), warm light (50-80 DEG C) and hot light (110-180 DEG C), the p-phenylene diisocyanate can be obtained. According to the method, the p-phenylenediamine and the di-(trichloromethyl) carbonate are respectively dissolved by adopting the two solvents with different boiling points, and therefore, reaction energy consumption is effectively reduced, the purity of the obtained p-phenylenediamine is up to 99% through the three reaction stages; and the yield of the p-phenylenediamine is up to 97.8%.
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Paragraph 0045-0056
(2020/10/20)
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- Preferred Binding of Carboxylates by Chiral Urea Derivatives Containing α-Phenylethyl Group
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An efficient, simple protocol for the synthesis of a new family of chiral ureas 1 – 4 is described. The binding properties of 1 – 4 toward different anion (acetate, benzoate, fluoride, and chloride) have been studied by1H-NMR titration and have been observed in the case of 4 is a selective receptor for acetate. The theoretical calculation M06/6-311+G(d,p) helped us explain the binding properties observed. The most interesting observation is that this calculated structure is consistent with expected, based on the concept of allylic 1,3-strain (A1,3strain). When chiral caboxylates were studied, urea 1 was the best in discriminating between enantiomers.
- Cortés-Hernández, Mayra,Rojas-Lima, Susana,Hernández-Rodríguez, Marcos,Cruz-Borbolla, Julián,López-Ruiz, Heraclio
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p. 416 - 424
(2016/07/06)
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- Chemical determination of the absolute structures of resveratrol dimers, ampelopsins A, B, D and F
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The absolute configurations of four stilbenedimers, (+)-ampelopsins A, (+)-ampelopsins B, (-)-ampelopsins D and (+)-ampelopsins F were respectively determined on the basis of chemical evidence.
- Takaya, Yoshiaki,Yan, Ke-Xu,Terashima, Kenji,Ito, Junko,Niwa, Masatake
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p. 7259 - 7265
(2007/10/03)
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- Synthesis of isocyanates from carbamate esters employing boron trichloride
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The conversion of carbamate esters to isocyanates and diisocyanates of industrial importance is possible using BCl3 in the presence of Et3N; the reaction is simple in execution and work-up, occurring under mild conditions and affording isocyanates in excellent yields.
- Butler,Alper
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p. 2575 - 2576
(2007/10/03)
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- Amid group-containing diisocyanates and amide group-containing epoxy resins
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An amide group-containing epoxy resin obtained by reacting an epoxy resin with an amide group-containing diisocyanate obtained by reacting a diisocyanate with a dicarboxylic acid gives a uniform cured article showing high adhesiveness and is usable as an adhesive, a coating composition, and the like.
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- Oxygen Atom Transfer With Niobocene Ketenes; Baeyer-Villiger Chemistry with Unusual Regioselectivities
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Niobocene ketene complex 1 has been utilized as an oxygen atom transfer reagent, converting ketones and aldehydes to esters and carboxylic acids.The steric properties of compound 1 give rise to a series of relative migratory aptitudes that differs from those seen for peracids.The process may be rendered catalytic in 1 with methyltrifluoromethyldioxirane (4). Key Words: Baeyer-Villiger reaction, niobocene complexes, ketenes, oxygen transfer, dioxiranes
- Fermin, Maria C.,Bruno, Joseph W.
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p. 7545 - 7548
(2007/10/02)
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- Process for the preparation of organic mono- and polyisocyanates
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A process for the preparation of organic mono- and polyisocyanates is described, in which a hydrogen chloride adduct of a trisubstituted urea is thermally decomposed to form the isocyanate. The hydrogen chloride adduct at minimum contains the stoichiometric amount of HCl, and at maximum a 10 mole-% excess. The process is carried out in a closed system at a temperature between about 80° and 180° C.; the reaction is effected either in a melt or in the presence of an inert organic solvent.
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- Ethylenic silicon compounds and thermoplastic elastomers obtained therefrom
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The invention provides organosilicon compounds of the formula: STR1 in which: N IS 1, 2 OR 3; Each R, which may be identical or different, is a monovalent organic group which contains a carbon-carbon double bond and from 2 to 10 carbon atoms; Each R1, which may be identical or different, is a straight or branched alkyl radical optionally substituted by one or more halogen atoms or cyano groups; an aryl radical or an alkylaryl radical optionally substituted by one or more halogen atoms; R2 is a straight or branched divalent alkylene or alkylidene radical possessing up to 4 carbon atoms; X is a divalent radical consisting of, or containing, at least one hetero-atom selected from oxygen, sulphur and nitrogen atoms, the radical being attached to the radical R2 via a said hetero-atom; G is an organic radical of valency (m+ l) possess from 1 to 30 carbon atoms; m is 1, 2 or 3; And each Y, which may be identical or different, is a functional group selected from: --NO2, STR2 --COOM (where M represents a sodium, potassium or lithium atom); --COOR4 ; STR3 --COCl; --OH; --OR4 ; STR4 --SH; --SR4 ; STR5 --CONH2 ; --CSNH2 ; --CN; --CH2 --NH2 ; --CHO; STR6 --NCO; STR7 wherein R3 represents a hydrogen atom or a straight or branched alkyl radical possessing up to 6 carbon atoms and R4 represents an alkyl radical possessing up to 4 carbon atoms, with the proviso that two Y groups can together constitute an imide group STR8 wherein R5 represents a hydrogen atom or a straight or branched alkyl radical possessing up to 4 carbon atoms. These are useful intermediates in the preparation of disilanes and silicon polymers, in particular of polyethylenic silicon compounds which can be polymerized with an α, ω-dihydrogenopolysiloxane to give thermoplastic elastomers.
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- Cyclic esters of 3,4-dihydroxy-thiophene-1,1-dioxide compounds and 3,4-dihydroxy-cyclopentadienone compounds
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Cyclic esters of 3,4-dihydroxy-thiophene-1,1-dioxide and of the corresponding cyclopentadienone compound, and their manufacture. The compounds can be used as "solid forms" of phosgene, thiophosgene or oxalyl chloride, or as acyl transfer agents.
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