Lewis Acids and Lewis Acid-Functionalized Ligands in Rhodium-Catalyzed Methyl Acetate Carbonylation
摘要:
The application of Lewis acids and Lewis acid-functionalized ligands as activators for methyl acetate in the rhodium-catalyzed carbonylation of methyl acetate to acetic anhydride has been investigated. The reaction of methyl acetate with B(C6F5)(3) results in the formation of the adduct [MeOAc center dot B(C6F5)(3)]. The combination of this adduct with [Rh(OAc)-(CO)(2)](2) results in a transfer of the Lewis acid to the rhodium complex, rather than an anticipated oxidative addition reaction. In a second approach, novel Lewis acid-functionalized rhodium-(I) complexes [Rh(CO)Cl(BPP)], [Rh(CO)(2)(EPP)]SbF6, and [Rh(MeCN)(2)(BPP)]SbF6 (BPP = PhB(C6H4PPh2)(2)) have been prepared. The lack of reactivity of [Rh(CO)(2)(BPP)]SbF6 toward MeOAc has shown that the rhodium boron interaction is too strong for activation of methyl acetate, and no carbonylation activity was observed under the conditions used.
Lewis Acids and Lewis Acid-Functionalized Ligands in Rhodium-Catalyzed Methyl Acetate Carbonylation
摘要:
The application of Lewis acids and Lewis acid-functionalized ligands as activators for methyl acetate in the rhodium-catalyzed carbonylation of methyl acetate to acetic anhydride has been investigated. The reaction of methyl acetate with B(C6F5)(3) results in the formation of the adduct [MeOAc center dot B(C6F5)(3)]. The combination of this adduct with [Rh(OAc)-(CO)(2)](2) results in a transfer of the Lewis acid to the rhodium complex, rather than an anticipated oxidative addition reaction. In a second approach, novel Lewis acid-functionalized rhodium-(I) complexes [Rh(CO)Cl(BPP)], [Rh(CO)(2)(EPP)]SbF6, and [Rh(MeCN)(2)(BPP)]SbF6 (BPP = PhB(C6H4PPh2)(2)) have been prepared. The lack of reactivity of [Rh(CO)(2)(BPP)]SbF6 toward MeOAc has shown that the rhodium boron interaction is too strong for activation of methyl acetate, and no carbonylation activity was observed under the conditions used.