Deuterium Discrimination in P--H/P--D Exchange of Phosphorous Acid

Abstract

Deuterium discrimination in P--H/P--D exchange is first reported. Quantitative 1 H and 31 P NMR analyses of the phosphorous acid in H 2 O/D 2 O solutions indicate that there is a strong discrimination against deuterium bonding with phosphorus. The ([PD]/[PH]) nmr ratio, where [PD] nmr and [PH] nmr are the NMR determined concentration of phosphorus attached to deuterium and proton, respectively, is only 67% of the stoichiometrical D/H ratio in the studied solutions. The very strong isotope discrimination should originate from the isotope effect in tautomerization involving an intermediate having the structure of P(OH) 3 where the three OH's are equivalent.

Keywords:

• Deuterium Discrimination
• Isotope Exchange
• Phosphorous Acids