Discovery of novel homogeneous rare earth catalysts by IR-thermography: epoxide opening with alcohols and Baeyer–Villiger oxidations with hydrogen peroxide

Berkessel, Albrecht; Ashkenazi, Eli; Andreae, Marc R. M.

doi:10.1016/s0926-860x(03)00260-6

Cited by 28 publications

(10 citation statements)

References 25 publications

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“…Alcohol assisted ringopening reactions of epoxides are well known. 57,58 This postulation was in agreement with the result from the thermal analysis, which revealed that the higher enthalpy of curing was obtained with the mixture containing starch. At 30 minutes, a low-intensity band was observed at 3456 cm À1 , which shied overtime to 3464 and 3476 cm À1 aer 60 and 90 minutes, respectively.…”

Section: Curing Study By Infrared Spectroscopysupporting

confidence: 88%

Bio-based thermoset composites from epoxidised linseed oil and expanded starch

et al. 2014

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a Bio-based thermoset composites comprising epoxidised linseed oil (ELO), a bio-derived diacid crosslinker (Pripol 1009) and starch are reported. High amylose corn starch in its native, gelatinised and retrograded forms were used in the formulation to yield water resistant films with good thermal stability. The textural properties of gelatinised and retrograded starches were characterised using scanning electron microscopy and porosimetry and their thermal stability was determined using thermogravimetric analysis. The inclusion of 20% gelatinised starch significantly improved the mechanical properties of the bio-based thermoset composite with tensile strength being enhanced by 227% and Young's modulus by 166% with respect to the starch-free counterparts. Unlike in formulations comprising native starch, no visible phase separation was noticed for gelatinised-or retrograded-starch thermosets. Thermal analysis and gel time study revealed retardation of the cure process in the presence of starch. However, the presence of hydroxyl groups within the starch was likely to promote a more extensive curing process, as indicated by the higher total enthalpy of reaction obtained. This was supported by thermal stability studies, which indicated a greater proportion of crosslinked material obtained in films with higher starch content.

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Section: Curing Study By Infrared Spectroscopysupporting

confidence: 88%

Bio-based thermoset composites from epoxidised linseed oil and expanded starch

et al. 2014

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“…Shibasaki et al [24] reported a procedure relying on catalysis by a galliumlithium-BINOL complex, which allowed the addition of paramethoxyphenol in good to excellent enantioselectivities (up to 96 % ee). [25] Early examples showed that different rare earth metal triflates are highly active catalysts for the alcoholysis of epoxides (Sc(OTf) 3 [26][27][28] and Yb(OTf) 3 [29] ). These works provided a good impetus for Schneider et al, who assessed the scope of alcoholysis of meso-epoxides catalyzed by using a chiral catalytic system composed of Sc(OTf) 3 (10 mol%) and Bolm's ligand).…”

Section: Introductionmentioning

confidence: 99%

“…Early examples showed that different rare earth metal triflates are highly active catalysts for the alcoholysis of epoxides (Sc(OTf) 3 [26–28] and Yb(OTf) 3 [29] ). These works provided a good impetus for Schneider et al., who assessed the scope of alcoholysis of meso ‐epoxides catalyzed by using a chiral catalytic system composed of Sc(OTf) 3 (10 mol%) and Bolm's ligand) [30,31] .…”

Section: Introductionmentioning

confidence: 99%

Highly Enantioselective Ring‐Opening of meso‐Epoxides with O‐ and N‐Nucleophiles Catalyzed by a Chiral Sc(III)/bipyridine Complex

et al. 2021

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The ring-opening of epoxides is a synthetically significant process widely applied in all kinds of chemistry. Herein, we report the catalytic and highly enantioselective variant of this reaction exploiting our recent endeavors to design and synthesize chiral bipyridine type ligands. A Sc-complex with a newly developed bipyridine ligand exhibited high reactivity and stereocontrol in the desymmetrization of meso-epoxides with various alcohols. The respective enantiomerically enriched 1,2alkoxyalcohols were obtained with e.r. values of up to 99.5:0.5 for various alcohols regardless of their nature (benzyl, alkyl, cycloalkyl, allyl, propargyl, etc.). We attempted ring-opening of meso-epoxides with anilines as well; however, it proceeded with lower enantioselectivity and was strongly depended on the electronic effect of substituents attached to the aromatic ring.

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“…Rare earth elements are attractive materials for industry and play an important role in a number of current technologies as active components. A number of applications of rare earth-activated materials have been developed, for instance in optical technologies, that have led expected to construction of photonic devices [1], catalytic [2][3][4][5][6] and photoluminescence [7] systems. In this connection, the low-temperature sol-gel synthesis has been recently of considerable scientific and technological interest [8].…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of SiO2–La2O3 gels obtained in a water-free environment

et al. 2014

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SiO 2-La 2 O 3 binary oxide system was prepared by the sol-gel method without addition of strong polar solvents (e.g. water, alcohol) to the initial system. Changes in the surface and gel network structure were described as a function of the type and concentration of the second component that is lanthanum oxide. A series of samples with Si to La molar ratios of 1:0.1, 1:0.25, 1:0.5, and 1:1 were characterised by XRD, TG-TA, FTIR, and lowtemperature nitrogen adsorption measurements. Results of the investigation showed that higher amounts of the lanthanum component in the binary oxide gel system led to a completely changed morphology of the porous structure of the surface gels obtained in a non-aqueous medium.

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Discovery of novel homogeneous rare earth catalysts by IR-thermography: epoxide opening with alcohols and Baeyer–Villiger oxidations with hydrogen peroxide

Cited by 28 publications

References 25 publications

Bio-based thermoset composites from epoxidised linseed oil and expanded starch

Bio-based thermoset composites from epoxidised linseed oil and expanded starch

Highly Enantioselective Ring‐Opening of meso‐Epoxides with O‐ and N‐Nucleophiles Catalyzed by a Chiral Sc(III)/bipyridine Complex

Synthesis and characterization of SiO2–La2O3 gels obtained in a water-free environment

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