- Mixed anhydrides: Key intermediates in carbamates forming processes of industrial interest
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Mixed anhydrides of carbonic acid with phosphonic or carbamic acid, are mimic of relevant biological systems, and behave as key intermediates in transesterification processes that afford carbamates of industrial interest. They are formed in the phosphonic acids mediated or direct transesterification reaction of organic carbonates with amines to afford carbamates and have been isolated and characterised in the solid state and solution. Their conversion into the products has been demonstrated to occur with high regioselectivity. The application of such intermediates in some synthetic processes is discussed.
- Aresta, Michele,Dibenedetto, Angela
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- METHOD FOR PRODUCING CARBAMATE AND METHOD FOR PRODUCING ISOCYANATE
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The present invention provides a method for producing a carbamate that includes a step (1) and a step (2) described below: (1) a step of producing a compound (A) having a urea linkage, using an organic primary amine having at least one primary amino group per molecule and at least one compound selected from among carbon dioxide and carbonic acid derivatives, at a temperature lower than the thermal dissociation temperature of the urea linkage; and(2) a step of reacting the compound (A) with a carbonate ester to produce a carbamate.
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Paragraph 0367-0368; 0379; 0399-0401; 0403
(2021/06/22)
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- METHOD FOR PRODUCING AMIDES OR POLYAMIDES BY USING AROMATIC CARBAMATES BY WAY OF ISOCYANATES AS PRECURSORS THROUGH CATALYZED THERMAL PROCESSES AND METHOD FOR PRODUCING AROMATIC CARBAMATE PRECURSORS FROM AROMATIC AMINES
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The present invention is directed to a process for preparing amides or polyamides by replacing isocyanate starting materials of a catalyzed thermal reaction with aromatic carbamates. Through the catalyzed thermal process involving a non-isocyanate precursor of the present invention, efficiency for producing amides or polyamides can be significantly improved, and the impure side products produced from a side reaction of isocyanate can be greatly curtailed. Hence, amides or polyamides of high purity and yield can be achieved. The invention also relates to a process for preparing aromatic carbamates, the new non-isocyanate precursors for amides or polyamides.
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Paragraph 0068-0069
(2018/07/29)
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- PROCESS FOR PRODUCING ISOCYANATE USING DIARYL CARBONATE
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An object of the present invention is to provide a process that enables isocyanate to be produced stably over a long period of time and at high yield without encountering problems of the prior art during production of isocyanate without using phosgene. The present invention provides an isocyanate production process including the steps of: obtaining a reaction mixture containing an aryl carbamate having an aryl group originating in a diaryl carbonate, an aromatic hydroxy compound originating in a diaryl carbonate, and a diaryl carbonate, by reacting a diaryl carbonate and an amine compound in the presence of a reaction solvent in the form of an aromatic hydroxy compound; transferring the reaction mixture to a thermal decomposition reaction vessel; and obtaining isocyanate by applying the aryl carbamate to a thermal decomposition reaction, wherein the reaction vessel in which the reaction between the diaryl carbonate and the amine compound is carried out and the thermal decomposition reaction vessel for the aryl carbamate are different.
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Page/Page column 49
(2011/02/18)
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- PROCESS FOR PRODUCING ISOCYANATES USING DIARYL CARBONATE
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An object of the present invention is to provide a process that enables isocyanate to be produced stably over a long period of time and at high yield without encountering problems of the prior art during production of isocyanate without using phosgene. The present invention provides an isocyanate production process including the steps of: obtaining a reaction mixture containing an aryl carbamate having an aryl group originating in a diaryl carbonate, an aromatic hydroxy compound originating in a diaryl carbonate, and a diaryl carbonate, by reacting a diaryl carbonate and an amine compound in the presence of a reaction solvent in the form of an aromatic hydroxy compound; transferring the reaction mixture to a thermal decomposition reaction vessel; and obtaining isocyanate by applying the aryl carbamate to a thermal decomposition reaction, wherein the reaction vessel in which the reaction between the diaryl carbonate and the amine compound is carried out and the thermal decomposition reaction vessel for the aryl carbamate are different.
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Page/Page column 39
(2011/04/14)
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- PROCESS FOR THE PREPARATION OF N-SUBSTITUTED CARBAMIC ACID ESTER AND PROCESS FOR THE PREPARATION OF ISOCYANATE USING THE N-SUBSTITUTED CARBAMIC ACID ESTER
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The present invention provides a method for producing N-substituted carbamic acid-O-aryl ester derived from a compound having an ureido group, the method comprising the step of carrying out esterification or esterification and transesterification from the compound having the ureido group and a hydroxy composition containing one type or a plurality of types of hydroxy compounds.
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Page/Page column 277
(2011/06/10)
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- Reaction of aromatic diamines with diphenylcarbonate catalyzed by phosphorous acids: A new clean synthetic route to mono- and dicarbamates
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In the presence of organophosphorus acids [Ph2P(O)OH, (PhO)2P(O)OH, (BuO)2P(O)OH, (BuO)P(O)(OH)2], aromatic diamines, such as 4,4'- methylendianiline (MDA) or 2,4-diaminotoluene (TDA), react with diphenylcarbonate (DPC) to afford in a very selective way mono- and dicarbamate phenyl esters. The carbamation process is strongly influenced by the temperature and solvent. The influence of both these factors on carbamate yield and selectivity has been investigated and we present in this study the kinetics of formation of both mono- and dicarbamate esters.
- Aresta, Michele,Dibenedetto, Angela,Quaranta, Eugenio
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p. 14145 - 14156
(2007/10/03)
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