2-methyl-1,2lambda5-oxaphospholane 2-oxide

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A mixture of 43 g (0.5 mole) of methacrylic acid and 69 g (0.5 mole) of 3-hydroxypropyl-methyl-phosphinic acid is added to 58.5 g (0.5 mole) of methyldichloro-phosphine at 50°-60° C., while hydrogen chloride is discharged. Subsequently heating takes place under water jet vacuum to an internal temperature of up to 150° C. The residue is distilled under reduced pressure. 35 g of 2-methyl-2-oxo-1,2-oxa-phospholane (boiling point at 1.5 mm Hg: 120°-130° C.) and 55 g of 2,4-dimethyl-2,5-dioxo-1,2-oxa-phospholane (boiling point at 0.7 mm Hg: 150°-155° C.) are obtained. The yield in 2,4-dimethyl-2,5-dioxo-1,2-oxa-phospholane represents 71% of the theoretical yield. Subsequently heating up to 150° C The residue is distilled under reduced pressure