A Thermolysis Study of Poly(trimethylene phenylphosphinate) and Poly(2,2-dimethyltrimethylene phenylphosphinate). NMR and X-ray Structure of 2-Oxo-2-phenyl-4,4-dimethyl-1,2-oxaphospholane

Article abstract of DOI:10.1021/jo00200a023

Thermal decomposition of poly(trimethylene phenylphosphinate) (2) and poly(2,2-dimethyltrimethylene phenylphosphinate) (2a) to 2-oxo-2-phenyl-1,2-oxaphospholane (3) and 2-oxo-2-phenyl-4,4-dimethyl-1,2-oxaphospholane (3a), respectively, has been described and the mechanism of their formation discussed.The X-ray crystal structure of oxaphospholane 3a has been determined and compared to its preferred conformation in solution inferred form 1H and 13C NMR data.Compound 3a crystallized in the monoclinic space group C2/c with eight molecules per unit cell of dimensions a = 26.688(5) Angstroem , b = 7.612(1) Angstroem, c = 11.305(3) Angstroem, and β = 98.88(2) deg.The stereochemistry of another decomposition product of 2a, namely, 4,4-dimethyl-2,6-diphenyl-1,2,6-oxadiphosphorinane 2,6-dioxide (4a), has also been deduced from its NMR data, and the mechanism of its formation is discussed.