title: First acyclic diene metathesis polymerization under biphasic conditions using a dicationic ruthenium alkylidene: access to high-molecular-weight polymers with very low ruthenium contamination.
abstract: The acyclic diene metathesis (ADMET) polymerization of 6-hydroxy-1,10-undecadiene (M1) and 6-acetoxy-1,10-undecadiene (M2) by the action of two different catalysts, i.e., the second-generation Grubbs-Hoveyda system ([RuCl2(IMesH2)(CH-2-(2-PrO-C6H4)]) (1) and the dicationic ruthenium alkylidene [Ru(DMF)3(IMesH2)(CH-2-(2-PrO-C6H4)] (2, IMesH2 = 1,3-dimesitylimidazolin-2-ylidene) is reported. Biphasic conditions using 1-butyl-2,3-dimethylimidazolium tetrafluoroborate ([BDMIM(+)BF4(-)]) and 1,2,4-trichlorobenzene (TCB) are applied. Under the chosen conditions (T = 75 °C, 20 mbar), the use of catalyst 1 results only in the formation of low-molecular-weight polymers (Mn ≤ 10,000 g mol(-1)), while catalyst 2 allows for the high yield synthesis of high-molecular-weight polymers (Mn ≤ 40,000 g mol(-1), yields ≤ 99%). Irrespective of the catalyst used, all polymers display a high trans-content (>95%). Notably, Ru-contamination of the target polymers without any additional purification is as low as 1.2 ppm with catalyst 2. Together with the high yields and high molecular weights, the low Ru-contaminations clearly illustrate the advantages of the biphasic setup.
authors.affiliation: Institute of Polymer Chemistry, University of Stuttgart, Pfaffenwaldring 55, D-70569, Stuttgart.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhao
authors.forename: Dongren
authors.initials: D
authors.lastname: Wang
authors.forename: Benjamin
authors.initials: B
authors.lastname: Autenrieth
authors.forename: Michael R
authors.initials: MR
authors.lastname: Buchmeiser
mesh_terms: D001881:Borates; D001888:Boric Acids / Q000737:chemistry; D002384:Catalysis; D002412:Cations / Q000737:chemistry; D002722:Chlorobenzenes / Q000737:chemistry; D006839:Hydrocarbons, Acyclic / Q000737:chemistry*; D007093:Imidazoles / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D015394:Molecular Structure; D008970:Molecular Weight; D011090:Polyenes / Q000737:chemistry*; D058105:Polymerization; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry*; D012428:Ruthenium / Q000737:chemistry*; D013055:Spectrophotometry, Infrared
chemical_list: C525965:1-butyl-2,3-dimethylimidazolium; D001881:Borates; D001888:Boric Acids; D002412:Cations; D002722:Chlorobenzenes; D006839:Hydrocarbons, Acyclic; D007093:Imidazoles; D011090:Polyenes; D011108:Polymers; C009947:1,2,4-trichlorobenzene; D012428:Ruthenium; C098759:fluoroboric acid
keywords: acyclic diene metathesis (ADMET) polymerization; biphasic; cationic; ionic liquid; ruthenium