0000000000459665
AUTHOR
Denise Baudry-barbier
Anionic Monosubstituted Cyclopentadienylsamarium Derivatives: Catalysts for a Stereospecific Isoprene Polymerization
New alkyl and allyl complexes 1–3 {1: [Cp′2Sm(C3H5)]n, Cp′ = Me3CC5H4; 2: [Me4C2(C5H4)2]Sm(C3H5)2Li(dme),dme = (CH3OCH2CH2OCH3); 3: Cp′2SmMe2Li(dioxane)} were synthesized from (Cp′2SmCl)2and from the magnesium derivative [Me4C2(C5H4)2]SmCl · MgCl2(THF)4 (4). The ansa anionic complex 2 exhibited good activity for the stereospecific 1,4-trans polymerization of isoprene, whereas the neutral derivative 1 was inactive. In the same way, the anionic complex [Cp′2SmMe2]Li(dioxane) (3) was found to be an ethylene polymerization catalyst of very short lifetime. The lack of reactivity of 1 is related to the associated structure of this coordinatively unsaturated complex: this fact was established by t…
Catalytic activity of rare-earth-supported catalysts in Friedel–Crafts acylations
Abstract Friedel–Crafts acylations are catalysed by rare-earth-supported catalysts. The preparation, characterization and performance of these solid catalysts in a test acylation reaction and in a variety of syntheses of aromatic ketones are reported. In contrast to the reactions using AlCl3, the experimental conditions are non-polluting and the final work-up does not require any aqueous treatment.
Friedel-Crafts catalytic alkylations using rare earth-based mineral supports
Abstract Rare earth halides supported on mineral supports (K10 montmorillonite and silica) were investigated as catalysts for Friedel-Crafts alkylations. This project concerns the replacement of the widely used Lewis acid AlCl3 in Friedel-Crafts reactions by environmentally friendly catalysts in that they circumvent the production of aluminum waste. The catalytic activity of these heterogeneous catalysts was established in a series of alkylations of aromatic compounds.