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1.
Kapil Shyam Lokare Nicolas Frank Beatrice Braun‐Cula Itziar Goikoetxea Joachim Sauer Christian Limberg 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2016,128(40):12513-12517
To gain molecular level insights into the properties of certain functions and units of extended oxides/hydroxides, suitable molecular model compounds are needed. As an attractive route to access such compounds the trapping of early intermediates during the hydrolysis of suitable precursor compounds with the aid of stabilizing ligands is conceivable, which was tested for the aluminum(III)/water system. Indeed, trisilanols proved suitable trapping reagents: their presence during the hydrolysis of AliBu2H in dependence on the amount of water used allowed for the isolation of tri‐ and octanuclear aluminum hydroxide cluster complexes [Al3(μ2‐OH)3(THF)3(PhSi(OSiPh2O)3)2] ( 1 ) and [Al8(μ3‐OH)2(μ2‐OH)10(THF)3(p‐anisylSi(OSiPh2O)3)4] ( 2 ). 1 can be regarded as the Al(OH)3 cyclic trimer, where six protons have been replaced by silyl residues. While 2 features a unique [Al8(μ3‐OH)2(μ2‐OH)10]12+ core. In contrast to most other known aggregates of this type, 1 and 2 can be readily prepared at reasonable scales, dissolve in common solvents, and retain an intact framework even in the presence of excessive amounts of water. This finding paves the way to future research addressing the reactivity of the individual functional groups. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(51):16560-16564
A novel approach for the umpolung α‐arylation of amides is presented. By the nucleophilic phenylation of O‐silyl N,O‐ketene acetals, generated in situ from N‐alkoxy amides, a phenyl group can be introduced onto the α‐carbon atom of amides through N−O bond cleavage in a two‐step, one‐pot process. The asymmetric synthesis of α‐aryl amides through the diastereoselective arylation of a chiral N,O‐ketene acetal is also described. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(41):12727-12730
The rational design of zeolite‐based catalysts calls for flexible tailoring of porosity and acidity beyond micropore dimension. To date, dealumination has been applied extensively as an industrial technology for the tailoring of zeolite in micropore dimension, whereas desilication has separately shown its potentials in the creation of mesoporosities. The free coupling of dealumination with desilication will bridge the tailoring at micro/mesopore dimensions; however, such coupling has been prevailingly confirmed as an impossible mission. In this work, a consecutive dealumination–desilication process enables the introduction of uniform intracrystalline mesopores (4–6 nm) into the microporous Al‐rich zeolites. The decisive impacts of steaming step have been firstly discovered. These findings revitalize the functions of dealumination in porosity tailoring, and stimulate the pursuit of new methods for the tailoring of industrially relevant Al‐rich zeolites. 相似文献
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《高分子科学杂志,A辑:纯化学与应用化学》2013,50(3):245-256
Abstract The polymerization of 1,3‐butadiene (BD) by the ternary Ziegler/Natta (Z/N) catalyst system neodymium versatate (NdV)/ethylaluminum sesquichloride (EASC)/aluminum alkyl is investigated. Special attention is paid to the impact of the aluminum alkyl on the polymerization kinetics and on the control of molar masses. In this respect diisobutyl aluminumhydride (DIBAH) and triisobutylaluminum (TIBA) are compared. Within a broad range of n Al‐Alkyl/n NdV‐ratios for both aluminum compounds the features of a living polymerization with a reversible exchange of the living polybutadienyl chains between neodymium (Nd) and aluminum are observed. The equilibrium position of this reaction is different for TIBA and DIBAH. At the same molar loadings DIBAH results in polybutadienes with molar masses which are 1/8 of those obtained in the presence of the cocatalyst TIBA. This difference is explained by a significantly more facile substitution of a hydride moiety from DIBAH than an isobutyl group from either DIBAH or TIBA by a living polybutadienyl chain. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2018,130(8):2241-2245
The hydrolysis reaction of aluminum can be decoupled into a battery by pairing an Al foil with a Pd‐capped yttrium dihydride (YH2–Pd) electrode. This hydrolysis battery generates a voltage around 0.45 V and leads to hydrogen absorption into the YH2 layer. This represents a new hydrogen absorption mechanism featuring electrical energy generation during hydrogen absorption. The hydrolysis battery converts 8–15 % of the thermal energy of the hydrolysis reaction into usable electrical energy, leading to much higher energy efficiency compared to that of direct hydrolysis. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(1):214-217
4‐Methylene‐1,3‐dioxolan‐2‐ones underwent oxidative addition of a Ni0 catalyst in the presence of Me2Al(OMe), followed by a coupling reaction with alkynes, to form δ,ϵ‐unsaturated β‐ketocarboxylic acids with high regio‐ and stereoselectivity. The reaction proceeds by [1,3] rearrangement of an enol metal carbonate intermediate and the formal reinsertion of CO2. 相似文献