Herein we report the mechanochemical Friedel‐Crafts alkylation of 1,3,5‐triphenylbenzene (TPB) with two organochloride cross‐linking agents, dichloromethane (DCM) and chloroform (CHCl3), respectively. During a thorough milling parameter evaluation, the DCM‐linked polymers were found to be flexible and extremely sensitive toward parameter changes, which even enables the synthesis of a polymer with a SSABET of 1670 m2/g, on par with the solution‐based reference. Contrary, CHCl3‐linked polymers are exhibiting a rigid structure, with a high porosity that is widely unaffected by parameter changes. As a result, a polymer with a SSABET of 1280 m2/g could be generated in as little as 30 minutes, outperforming the reported literature analogue in terms of synthesis time and SSABET. To underline the environmental benefits of our fast and solvent‐free synthesis approach, the green metrics are discussed, revealing an enhancement of the mass intensity, mass productivity and the E‐factor, as well as of synthesis time and the work‐up in comparison to the classical synthesis. Therefore, the mechanochemical polymerization is presented as a versatile tool, enabling the generation of highly porous polymers within short reaction times, with a minimal use of chlorinated cross‐linker and with the possibility of a post polymerization modification.
A novel, efficient approach for the functionalization of microcrystalline cellulose (MCC) is presented. The as-obtained material allows the immobilization of chiral dirhodium catalysts preserving their enantioselectivity in asymmetric cyclopropanation reactions. As model, microcrystalline cellulose is modified with a polyethylene glycol derived linker, and Rh2(S-DOSP)4 is grafted on the material to produce a heterogeneous catalyst. SEM images at different stages of the immobilization show an unchanging uniform morphology, providing constantly good separation characteristics. The modification of the cellulose material with the polyethylene derived linker and the immobilization process are monitored using DNP enhanced 1H → 13C CP MAS NMR, quantitative 19F MAS NMR, TGA and ICP-OES analysis, confirming the success of the immobilization as well as the stability of bonds between the used linker molecule and the cellulose material. Finally, the evaluation of the produced catalyst is demonstrated in the asymmetric cyclopropanation reaction between styrene and methyl(E)-2-diazo-4-phenylbut-3-enoate showing excellent enantioselectivity with an ee of nearly 90% over a wide temperature range as well as good recyclability characteristics in four consecutive catalysis cycles.
The donor properties of a set of bulky ferrocene based bisphosphanes (Fe(C5H4PMes2)2 and (C5H4PMes2)Fe(C5H4PtBu2 with Mes= mesityl and tBu=tert‐butyl) were probed by exploring the NMR parameters of the corresponding selenophosphoranes amended by cyclovoltammetry. The ligand properties were explored in the complexation of copper phenylacetylide which is relevant as intermediate in the Cu(I) catalyzed CO2 addition to phenylacetylene. Owing to the poor solubility of the resulting complexes their characterization was performed with solid state NMR spectroscopy amended by IR spectroscopy, mass spectrometry and elemental analysis. Remarkably, these complexes feature luminescent properties, albeit with limited quantum yield.
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