Patent Watch
July 6, 2009 [Repeated from 3/23/09]
Run a ring-closing metathesis reaction in a supercritical fluid. W. Leitner and co-inventors describe a metathesis process that is carried out in liquid CO2 and specifically covers the production of the multifunctional compound 2 from 1. Surprisingly, the patent makes no mention of the use of 2 or the origin of 1.
Metathesis reactions of functional olefins have been used for many years, and the production of cyclic molecules by this reaction usually uses homogeneous catalysts that are predominantly ruthenium complexes. The use of supercritical fluids (SCFs) such as scCO2 as solvents in many reactions is increasing, and combining CO2 with conventional solvents enhances the solvent properties of the mixture under supercritical conditions. The inventors describe a process that combines scCO2 and an ionic liquid to allow the solubilization of the ruthenium catalyst in the ionic liquid while the reactant and product dissolve in the scCO2.
Examples are given for batch and continuous reaction systems. The preferred catalysts are fivefold coordinated Ru–carbene complexes such as 3 (Mes is mesityl); an example of the ionic liquid used is 4. The reaction shown illustrates the process for producing 2 from 1; like all metathesis reactions, a second olefin is formed. The reaction is carried out in a continuously flowing system that the inventors describe in detail. The reaction is followed by HPLC, but the manner of isolating the product from the continuous reaction is not given. In the batch example, the reaction mixture is extracted with toluene to give an oil that shows a 2/1 ratio of 59:1. The ratio in the continuous experiments varies from 0.02:1 to 5.4:1, indicating that the batch process is more efficient. (Boehringer Ingelheim International [Ingelheim, Germany]; Studiengesellschaft Kohle [Mülheim an der Ruhr, Germany]. US Patent 7,482,501, Jan. 27, 2009; Keith Turner)
View patent information from CAS.
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