Synlett 2010(14): 2189-2192  
DOI: 10.1055/s-0030-1258505
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Synthesis of TRIP and Analysis of Phosphate Salt Impurities

Martin Klussmann*, Lars Ratjen, Sebastian Hoffmann, Vijay Wakchaure, Richard Goddard, Benjamin List*
Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
Fax: +49(208)3062999; e-Mail: klusi@mpi-muelheim.mpg.de; e-Mail: list@mpi-muelheim.mpg.de;
Further Information

Publication History

Received 21 May 2010
Publication Date:
16 July 2010 (online)

Abstract

The chiral phosphoric acid TRIP, a useful Brønsted acid catalyst, easily becomes contaminated with metal impurities in the form of phosphate salts during synthesis. This significantly reduces the content of free acid in the product which can hamper the catalytic activity. Methods to easily judge whether TRIP contains mainly the free acid or phosphate salts are presented, using ¹H NMR spectroscopy or a simple pH test. An improved synthetic protocol for TRIP was established that reliably produces the free acid.

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CCDC 777645 contains the supplementary crystallographic data for TRIP˙MeCN˙0.5H2O. These data can be obtained from The Cambridge Crystallographic Centre via www.ccdc.cam.ac.uk/data_request/cif.