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Nitro Promoters for Selectivity Control in the Core Hydrogenation of Toluidines: Controlling Adsorption on Catalyst Surfaces
Author(s) -
GebauerHenke Ewa,
Tomkins Patrick,
Leitner Walter,
Müller Thomas E.
Publication year - 2014
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201402493
Subject(s) - chemoselectivity , nitro , catalysis , ruthenium , chemistry , selectivity , substrate (aquarium) , combinatorial chemistry , adsorption , molecule , organic chemistry , alkyl , oceanography , geology
The diastereoselectivity in the hydrogenation of multi‐substituted aromatic ring systems was used as a sensitive tool to gain molecular‐level insight into the reaction pathways on the surface of ruthenium. Here, the hydrogenation of para ‐, meta ‐, and ortho ‐toluidine was studied in detail. The chemoselectivity towards primary or secondary amines depends primarily on the choice of the metal; notably, nitro compounds such as NaNO 2 are highly effective promoters for ruthenium catalysts, which significantly increase the chemoselectivity towards primary amines as well as catalytic activity. Lower activation energy and altered diastereoselectivity indicate that in the presence of nitro additives, the substrate molecules are adsorbed in a coordination mode favourable for the hydrogenation of the aromatic ring.