Investigations into the Oxidative Stability of Hydroxymethyl- and Bis(Hydroxymethyl)-Phosphines

Abstract

Polydentate ligands containing the bis(hydroxymethyl)phosphine unit have been reported to exhibit enhanced oxidative stability, which would make them attractive for use in ^99mTc-radiopharmaceutical imaging agents. Benzylethyl(hydroxymethyl)phosphine, benzylbis(hydroxymethyl)phosphine and benzyldiethylphosphine were prepared in order to investigate the origin of this oxidative stability. Little evidence was found to indicate that the hydroxymethylphosphines show an enhanced level of stability, but it was demonstrated that the reaction conditions employed in their preparation generated a number of closely related by-products, which are likely to limit the usefulness of the hydroxymethylphosphines in commercial radiopharmaceutical applications.

Keywords:

• Hydroxymethylphosphine
• Oxidation
• Stability
• Tc-99m Radiopharmaceuticals

Acknowledgments

The authors wish to thank the EPSRC for financial support for HJG. They also wish to thank M. Motevalli for obtaining the X-ray crystallography data.