Ep. Segstro et al., CYCLIC-ACYCLIC EQUILIBRIUM AND SELECTIVE P-O BOND-CLEAVAGE IN 2-HYDROXYPHENYLDIPHENYL-PHOSPHINATE, PH2P(O)OC6H4OH, Canadian journal of chemistry, 76(5), 1998, pp. 518-521
The equilibrium in the Ph2P(O)OC6H4OH-base system may be shifted by va
rying the base concentration, where base = imidazole, triethylamine, d
imethyl sulfoxide, pyridine, and 1,4-dioxane. This equilibrium was stu
died by P-31 and H-1 NMR, and information about the symmetry of phosph
orus-containing intermediates is provided by the H-1 NMR spectrum of t
he catecholyl ring, with its ABCD spin system. The equilibrium is also
affected by trifluoroacetic acid. A mechanism is proposed that involv
es protonation-deprotonation, cyclic-acyclic equilibria, and selective
P-O bond cleavage, with all steps occurring rapidly on the NMR time s
cale.