title: A novel classification of Lewis acids on the basis of activity and selectivity.
abstract: Group 3-15 metal chlorides (Lewis acids) were classified on the basis of activity and aldehyde- and aldimine-selectivity in an addition reaction of a silyl enol ether. Based on the experimental results, metal chlorides (Lewis acids) were classified as follows: A, active; B, weak; C, inactive for the activation of the aldehyde and/or aldimines. Groups A and B were further divided into A-1 or B-1 (aldehyde-selective), A-2 or B-2 (aldimine-selective), and A-3 or B-3 (neutral). The final classification is as follows: A-1, BCl3, AlCl3, TiCl4, GaCl3, ZrCl4, SnCl4, SbCl5, SbCl3, HfCl4, ReCl5; A-2, ScCl3, FeCl3, InCl3, BiCl3; A-3, NbCl5, MoCl3. MoCl5, SnCl2, TaCl5, WCl5. WCl6, ReCl3, TlCl3; B-1, none; B-2, SiCl4, FeCl2, CoCl2, CuCl, CuCl2, GeCl4, YCl3, OsCl3, PtCl2; B-3, ZnCl2, RuCl3; C, VCl3, CrCl3, MnCl2, NiCl2, RhCl3, PdCl2, AgCl, CdCl2, IrCl3, AuCl, HgCl2, HgCl, PbCl2. This classification has revealed several new fundamental aspects of elements (metal chlorides) as Lewis acids.
authors.affiliation: Graduate School of Pharmaceutical Sciences, The University of Tokyo, CREST, Japan Science and Technology Corporation. skobayas@mol.f.u-tokyo.ac.jp
authors.forename: S
authors.initials: S
authors.lastname: Kobayashi
authors.forename: T
authors.initials: T
authors.lastname: Busujima
authors.forename: S
authors.initials: S
authors.lastname: Nagayama
mesh_terms: D000143:Acids / Q000737:chemistry / Q000145:classification*; D002384:Catalysis; D009682:Magnetic Resonance Spectroscopy
chemical_list: D000143:Acids