A NOVEL ROUTE TO AN AMINOPHOSPHONIC ACID BY THERMOLYSIS OF A POLY(URETHANE PHOSPHONATE). THE BETAIN FORM OF 3-ETHYL-2-HYDROXY-2-OXO-1,4,2-OXAZA-PHOSPHORINANE. STRUCTURE AND PROPERTIES

Abstract

A poly(urethane phosphonate) was obtained via transesterification of phosphonic acid diesters with hydroxyalkyl carbamate based on propylene carbonate and 2-aminoethanol. Thermolysis of the poly(urethane phosphonate) yielded the betain form of 3-ethyl-2-hydroxy-2-oxo-1,4,2-oxazaphosphorinane. The structure of this novel cyclic aminophosphonic acid monoalkylester was established by ¹³C{¹H}-, ³¹P- and ³¹P{¹H}-NMR-spectra supported by Molecular Modeling (MOPAC93 with AM1 and PM3). Stability-and dissociation constants were determined for the protolytic equilibrium (H₂L⁺, HL, L⁻) involving the betain of 3-ethyl-2-hydroxy-2-oxo-1,4,2-oxazaphosphorinane.

Key Words:

• phosphonic acid diesters
• poly(urethane phosphonate)
• thermolysis
• 1,4,2-oxazaphosphorinane
• NMR
• molecular modeling
• stability constants
• dissociation constants