# US 10,501,406 B2 · Low by-product content polyphenylene polymethylene polyisocyanates > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,501,406 B2 - Document ID: US10501406B2 - Status: Granted - Kind: B2 - Application number: 15/546,871 - Filed: 2016-01-22 - Published: 2018-01-11 - Granted: 2019-12-10 - Earliest claimed: 2015-01-30 - Assignees: BASF SE - Applicants: BASF SE - Inventors: Michael Lorenz; Axel Franzke; Robert Baumann; Michael Bock; Geert Janssens - Web page: https://patentgrep.com/patent/US10501406B2 ## CPC - C07C 263/04: from or via carbamates or carbamoyl halides - C07C 265/14: containing at least two isocyanate groups bound to the same carbon skeleton - C07C 269/04: from amines with formation of carbamate groups - C07C 271/28: to a carbon atom of a non-condensed six-membered aromatic ring - C08G 18/7692: {containing at least one isocyanate or isothiocyanate group linked to an aromatic ring by means of an aliphatic group} - G01R 33/46: NMR spectroscopy - C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS - C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) ## Abstract The invention relates to polyphenyl polymethylene polyisocyanates having an NCO number of at least 29% comprising less than 2% by weight ureas, less than 8% by weight carbodiimides or uretonimines and less than 1000 ppm organic chlorine compounds. The polyphenyl polymethylene polyisocyanates can be prepared according to the invention by reacting (i) polyphenyl polymethylene polyamines with organic carbonates to give the corresponding polyphenyl polymethylene polycarbamates, (ii) by thermally cleaving the polyphenyl polymethylene polycarbamates to give the polyphenyl polymethylene polyisocyanates, wherein, prior to the thermal cleavage, the free amino groups or urea groups present in the carhamate crude mixture comprising the polyphenyl polymethylene polycarbamates are reacted with a derivatizing reagent to give amide groups or urethane groups. The polyphenyl polymethylene polyisocyanates can further be prepared according to the invention, prior to the thermal cleavage, by removing compounds having free amino groups or urea groups present in the carbamate crude mixture from the carbamate crude mixture by filtration of the carbamate crude mixture comprising the polyphenyl polymethylene polycarbamates over a solid acidic adsorbent in the presence of an acid dissolved in the carbamate crude mixture. ## Claims ### Claim 1 A method for preparing a polyphenyl polymethylene polyisocyanate having an NCO number, determined according to DIN EN ISO 14896, of at least 29% comprising less than 2% by weight ureas, determined by NMR, less than 8% by weight carbodiimides or uretonimines, determined by NMR, and less than 1000 ppm organic chlorine compounds, determined by high-resolution mass spectrometry or according to ASTM D4663-10, the method comprising: reacting a polyphenyl polymethylene polyamine with an organic carbonate to give a corresponding polyphenyl polymethylene polycarbamate; thermally cleaving the polyphenyl polymethylene polycarbamate to give the polyphenyl polymethylene polyisocyanate; and prior to the thermally cleaving, reacting free amino groups or urea groups present in a carbamate crude mixture comprising the polyphenyl polymethylene polycarbamate with a derivatizing reagent to give amide groups or urethane groups. ### Claim 2 (depends on 1) The method according to claim 1, wherein the derivatizing reagent is at least one selected from the group consisting of an ester, an acid anhydride, and an acyl chloride of an aliphatic carboxylic acid having 1 to 10 carbon atoms or an aromatic carboxylic acid having 7 to 14 carbon atoms. ### Claim 3 (depends on 1) The method according to claim 1, wherein the derivatizing reagent comprises at least one of acetic anhydride and acetyl chloride. ### Claim 4 (depends on 1) The method according to claim 1, wherein the derivatizing reagent comprises at least one of a chlorothrmic ester and a pyrocarbonate of C1-C8-alkanols. ### Claim 5 (depends on 1) The method according to claim 1, wherein the reacting of the free amino groups or the urea groups with the derivatizing reagent is carried out in a solvent. ### Claim 6 (depends on 5) The method according to claim 5, wherein the solvent is at least one of an aromatic hydrocarbon and a chlorohydrocarbon having 6 to 20 carbon atoms. ### Claim 7 (depends on 1) The method according to claim 1, wherein the thermally cleaving of the polyphenyl polymethylene polycarbamate is effected by heating in a solvent to a temperature of 180 to 300° C. ### Claim 8 (depends on 7) The method according to claim 7, wherein the solvent is at least one of an aromatic hydrocarbon or a chlorohydrocarbon having 6 to 20 carbon atoms. ### Claim 9 (depends on 1) The method according to claim 1, wherein N-arylcarbamate is prepared by reacting an aromatic amine with a dialkyl carbonate in the presence of bases and hydrolysis of a resulting metal carbamate. ### Claim 10 (depends on 9) The method according to claim 9, wherein the dialkyl carbonate is at least one selected from the group consisting of diethyl carbonate, di-n-propyl carbonate, di-n-butyl carbonate, di-2-methylpropyl carbonate, di-3-methylbutyl carbonate, di-n-pentyl carbonate, bis-2-methoxyethyl carbonate, bis-2-ethoxyethyl carbonate, bis-2,2,2-trifluoroethyl carbonate and diisobutyl carbonate.