# US 6,720,397 B2 · Polymerization process for preparing syndiotactic 1,2-polybutadiene > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 6,720,397 B2 - Document ID: US6720397B2 - Status: Granted - Kind: B2 - Application number: 10/079,205 - Filed: 2002-02-20 - Published: 2003-09-04 - Granted: 2004-04-13 - Earliest claimed: 2002-02-20 - Assignees: Bridgestone Corporation - Inventors: Steven Luo - Web page: https://patentgrep.com/patent/US6720397B2 ## CPC - C08F 136/06: Butadiene - C08F: MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS ## Abstract A process for synthesizing syndiotactic 1,2-polybutadiene, the process comprising the steps of (1) polymerizing monomer consisting essentially of 1,3-butadeine monomer within an organic solvent that includes at least 50% by weight of aliphatic solvent by using an iron-based catalyst composition, where said step of polymerizing occurs at a temperature above about 65° C., thereby forming a supersaturated solution of syndiotactic 1,2-polybutadiene, (2) maintaining the supersaturated solution of syndiotactic 1,2-polybutadiene at a temperature above about 65° C. until isolation of the syndiotactic 1,2-polybutadiene is desired, and (3) isolating the syndiotactic 1,2-polybutadiene from the supersaturated solution. ## Claims ### Claim 1 A process for synthesizing syndiotactic 1,2-polybutadiene, the process comprising the steps of: (1) polymerizing monomer consisting essentially of 1,3-butadiene monomer within an organic solvent that includes at least 50% by weight of aliphatic solvent by using an iron-based catalyst composition, where said step of polymerizing occurs at a temperature above about 65° C., thereby forming a supersaturated solution of syndiotactic 1,2-polybutadiene; (2) maintaining the supersaturated solution of syndiotactic 1,2-polybutadiene at a temperature above about 65° C. until isolation of the syndiotactic 1,2-polybutadiene; and (3) isolating the syndiotactic 1,2-polybutadiene from the supersaturated solution. ### Claim 2 (depends on 1) The process of claim 1, where the solvent includes at least 85% by weight of aliphatic solvents. ### Claim 3 (depends on 2) The process of claim 2, where the solvent includes at least 95% by weight of aliphatic solvents. ### Claim 4 (depends on 3) The process of claim 3, where the solvent consists essentially of technical-grade hexane. ### Claim 5 (depends on 1) The process of claim 1, where said step of polymerizing occurs at a temperature above about 70° C. ### Claim 6 (depends on 1) The process of claim 1, where said step of polymerizing occurs at a temperature above about 80° C. ### Claim 7 (depends on 1) The process of claim 1, where the iron-based catalyst composition is formed by combining (a) an iron-containing compound, (b) a hydrogen phosphite, and (c) an organoaluminum compound. ### Claim 8 (depends on 7) The process of claim 7, where the organoaluminum compound includes a aluminoxane. ### Claim 9 (depends on 7) The process of claim 7 where the molar ratio of the organoaluminum compound to the iron-containing compound (Al/Fe) is at least about 12:1. ### Claim 10 (depends on 9) The process of claim 9 where the molar ratio of the organoaluminum compound to the iron-containing compound (Al/Fe) is at least about 13:1. ### Claim 11 (depends on 10) The process of claim 10 where the molar ratio of the organoaluminum compound to the iron-containing compound (Al/Fe) is at least about 14:1. ### Claim 12 A process for synthesizing syndiotactic 1,2-polybutadiene, the process comprising the steps of: (1) polymerizing 1,3-butadiene monomer within an aliphatic solvent by using an iron-based catalyst composition, where said step of polymerizing occurs at a temperature above about 65° C., thereby forming a supersaturated solution of syndiotactic 1,2-polybutadiene; (2) maintaining the supersaturated solution of syndiotactic 1,2-polybutadiene at a temperature above about 65° C. until isolation of the syndiotactic 1,2-polybutadiene; and (3) isolating the syndiotactic 1,2-polybutadiene from the supersaturated solution. ### Claim 13 (depends on 12) The process of claim 12, where the iron-based catalyst composition is formed by combining (a) an iron-containing compound, (b) a hydrogen phosphite, and (c) an organoaluminum compound. ### Claim 14 (depends on 13) The process of claim 13, where the molar ratio of the organoaluminum compound to the iron-containing compound (Al/Fe) is at least about 12:1. ### Claim 15 A process for synthesizing syndiotactic 1,2-polybutadiene wherein an iron-based catalyst system is employed to polymerize 1,3-butadiene monomer within an organic solvent comprising an aliphatic solvent, the improvement comprising: (1) conducting the polymerization at a temperature above 65° C. to form a supersaturated solution of syndiotactic 1,2-polybutadiene; and (2) maintaining the supersaturated solution at a temperature above about 65° C. until the isolation of the syndiotactic 1,2-polybutadiene. ### Claim 16 (depends on 15) The process of claim 15, further comprising the step of isolating the syndiotactic 1,2-polybutadiene from the supersaturated solution. ### Claim 17 (depends on 15) The process of claim 15, where the iron-based catalyst composition is formed by combining (a) an iron-containing compound, (b) a hydrogen phosphite, and (c) an organoaluminum compound. ### Claim 18 (depends on 17) The process of claim 17, where the molar ratio of the organoaluminum compound to the iron-containing compound (Al/Fe) is at least about 12:1.