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Author: Sharif, Muhammad × Publisher: Basel : MDPI ×

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    Effects of substitution pattern in phosphite ligands used in rhodium-catalyzed hydroformylation on reactivity and hydrolysis stability
    (Basel : MDPI, 2019) Kloß, Svenja; Selent, Detlef; Spannenberg, Anke; Franke, Robert; Börner, Armin; Sharif, Muhammad
    The stability of homogeneous catalytic systems is an industrially crucial topic, which, however, receives comparatively little attention from academic research. Phosphites are among the most frequently used ligands in industrial, rhodium-catalyzed n-regioselective hydroformylation. However, they are particularly vulnerable to hydrolysis. Since the decomposition of ligands should be dependent on the substitution patterns, phenyl, tert-butyl and condensed ring systems of benzopinacolphosphites were evaluated concerning their activity, regioselectivity and hydrolysis stability. A series of twelve strongly related phosphites were synthesized, tested in the hydroformylation of isomeric n-octenes, and studied in hydrolysis experiments using in situ NMR spectroscopy. Our results show that substituents in the ortho-position, especially tert-butyl substituents, enhance hydrolysis stability while maintaining compelling activity and regioselectivity. In contrast, substituents in the para-position may destabilize the phosphite. © 2019 by the authors. Licensee MDPI, Basel, Switzerland.
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    Facile synthesis of iron-titanate nanocomposite as a sustainable material for selective amination of substitued nitro-arenes
    (Basel : MDPI, 2020) Sohail, Manzar; Tahir, Nimra; Rubab, Anosha; Beller, Matthias; Sharif, Muhammad
    The fabrication of durable and low-cost nanostructured materials remains important in chemical, biologic and medicinal applications. Particularly, iron-based nanomaterials are of central importance due to the ‘noble’ features of iron such as its high abundance, low cost and non-toxicity. Herein we report a simple sol–gel method for the synthesis of novel iron–titanium nanocomposite-based material (Fe9TiO15@TiO2). In order to prepare this material, we made a polymeric gel using ferrocene, titanium isopropoxide and THF precursors. The calcination of this gel in air at 500◦C produced Fe-Ti bimetallic nanoparticles-based composite and nano-TiO2 as support. Noteworthy, our methodology provides an excellent control over composition, size and shape of the resulting nanoparticles. The resulted Fe-based material provides a sustainable catalyst for selective synthesis of anilines, which are key intermediates for the synthesis of several chemicals, dyes and materials, via reduction of structurally diverse and functionalized nitroarenes. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.