A new carboxylating reagent ((-)CH(2)CN/CO(2)) was obtained by bubbling CO(2) in a CH(3)CN-TEAP (tetraethylammonium perchlorate) solution previously electrolyzed under galvanostatic control. Organic carbamates were isolated from these solutions after addition of amines and an alkylating agent. In this paper, we describe the optimized conditions for the electrochemical synthesis of carbamates from amines
benzylamine, CO2 and methanol. The yield of methyl benzylcarbamate reached 92% at >99% benzylamine conversion and 92% benzylamine-based selectivity even in the absence of the dehydrating agents. The catalyst is reusable after the calcination at 873 K for 3 h. Various carbamates can be synthesized with good yield and high selectivity by the reaction of amines + CO2 + alcohols over CeO2. The main formation
Verfahren zur Herstellung von Isocyanaten durch thermische Spaltung von Urethanen
申请人:BASF Aktiengesellschaft
公开号:EP0078005A1
公开(公告)日:1983-05-04
Zur Herstellung von Isocyanaten, vorzugsweise Alkyl-mono- und/oder -polyisocyanaten oder Aryl-mono- und/oder polyisocyanaten, werden die entsprechenden Urethane bei Temperaturen von 175 bis 600°C in Gegenwart von Kohlenstoff, vorzugsweise in einem gerührten Kohlenstoffbett oder einem Wirbelbett mit Kohlenstoffschüttung, thermisch gespalten.
METHOD FOR TREATMENT OF ISOCYANATE RESIDUE, AND METHOD FOR TREATMENT OF CARBONATE
申请人:Mitsui Chemicals, Inc.
公开号:EP2518044A1
公开(公告)日:2012-10-31
A method for treating an isocyanate residue, which comprises carrying out a thermal decomposition reaction of a carbamate that is produced by the reaction among an amine, urea and/or an N-unsubstituted carbamic acid ester and an alcohol to produce a decomposition solution, separating an isocyanate and the alcohol from the decomposition solution to produce the isocyanate residue, and bringing the isocyanate residue into contact with high-pressure/high-temperature water to decompose the isocyanate residue into an amine; and a method for treating a carbonate, which comprises bringing the carbonate into contact with high-pressure/high-temperature water to decompose the carbonate into an alcohol.
A new electrochemical procedure for the synthesis of organic carbamates from amines and carbon dioxide has been developed using selective cathodic reduction of carbon dioxide in CO2-saturated room-temperature ionic liquid BMIm-BF4 solutions containing amines 1a-j, followed by addition of EtI as an alkylating agent. The synthesis was carried out under mild (P-CO2 = 1.0 atm, t = 55 degrees C) and safe conditions, and the use of volatile and toxic solvents and catalysts (according to the growing demand for ecofriendly synthetic methodologies), as well as of any supporting electrolyte (for a very easy workup of the reaction mixture), was avoided. Carbamates 2a-j were isolated in good to high yields.