- Composition and properties of the reaction products of p-cresol with camphene
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The products of the reaction between p-cresol and camphene were isolated and characterized. Their antiradical activity and toxicity were studied. The pharmacological activity of the most active stereoisomer of 2,6-diisobornyl-4-methyl phenol in rats with
- Chukicheva, I. Yu.,Buravlev,Dvornikova,Fedorova,Chernysheva,Aliev,Smol’yakova,Anishchenko,Sidekhmenova,Plotnikov,Kutchin
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- Scandium versus yttrium{amino-alkoxy-bis(phenolate)} complexes for the stereoselective ring-opening polymerization of racemic lactide and β-butyrolactone
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Scandium and yttrium amide complexes Ln{ONXOR1,R2}(N(SiHMe2)2)(THF)n(Ln = Sc, n = 0 or Y, n = 1; X = NMe2or OMe; R1= Cumyl or p-Cl-Cumyl; R2= Me or Cumyl) were prepared by aminolysis of Ln[N(SiHMe2)2]3(THF) with the corresponding tetradentate diamino- or alkoxy-amino-bis(phenol) pro-ligands {ONXOR1,R2}H2. In the solid state and in toluene solution, the scandium complexes are monomeric and 5-coordinated, while the analogous yttrium complexes all bear an extra THF-coordinated molecule and are 6-coordinated. Sc{ONXOR1,R2}(N(SiHMe2)2) complexes are single-site initiators for the ring-opening polymerization (ROP) of racemic lactide but are less active than their yttrium analogues Y{ONXOR1,R2}(N(SiHMe2)2)(THF); also, in contrast to the latter ones, they are inactive in the ROP of the more demanding racemic β-butyrolactone. On the other hand, the scandium amide complexes feature a significantly improved control over the ROP of lactide, yielding PLAs with much narrower molecular weight distributions (DMr= 0.88 vs. 0.83), while the opposite is observed with complexes based on p-methyl-substituted ligands (Pr= 0.50 in toluene or 0.72-0.75 in THF for Y vs. Pr= 0.75-0.83 for Sc in toluene). These reactivity and selectivity trends are rationalized by a much more sterically crowded coordination sphere in scandium than in yttrium complexes.
- Chapurina, Yulia,Klitzke, Joice,Awada, Mouhamad,Kirillov, Evgueni,Carpentier, Jean-Franois,Casagrande, Osvaldo De L.,Dorcet, Vincent
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