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Updated: Jun 11, 2025

Synthesis of High Purity Nonsymmetric Dialkylphosphinic Acid Extractants
Published on: October 19, 2017
Fortuitous Enantiomeric Self-Rectification of an Unreported Partial Racemisation in the Synthesis of a Chiral
Ben M J Lancaster1, Andrew J P White1, D Christopher Braddock1
1Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, White City Campus, 82 Wood Lane, London, W12 0BZ, UK.
Abstract:
Racemisation without Consequence: MOM deprotection during a routine synthesis of phosphoric acid 1 promoted partial racemisation of the product BINOL 5. Surprisingly, however, after phosphorylation of the partially racemised BINOL, enantiopure acid 1 was isolated. Further inspection revealed that during phosphorylation, unhydrolysed racemic phosphorochloridate 6 precipitated, thus restoring homochirality in the product phosphoric acid 1. Moreover, MOM deprotection partial racemisation was avoided by conducting reactions at lower temperatures for no longer than the required deprotection time, and/or by application of other deprotection conditions from the literature.
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