Synthesis
General procedure for the synthesis of 9,10-dihydro-9-oxa-10-phosphaphenanthrene from 10-chloro-9,10-dihydro-9-oxa-10-phosphaphenanthrene: 10 g of 6-chloro-6H-dibenzo[c,e][1,2]oxaphosphorine (0.0426 mol), 1.2 g of hydrochloric acid (0.0335 mol), and 2.1 g of water were added to a reactor and stirred for 5 minutes to form a homogeneous solution. The reaction mixture was heated at 80 °C for 1 h. Upon completion of the reaction, the system was divided into an organic layer and an aqueous layer. The temperature of the organic layer was maintained at 80 °C, and the organic layer was separated and transferred to another reactor. Reduced pressure distillation was carried out at 165 °C and 0.3 mbar to give 9.03 g of the white solid product 9,10-dihydro-9-oxa-10-phospha-phenanthrene-10-oxide [Yield: 98%; Color: 8 Hazen; Purity: 99.25% (major component: minor component = 99.25%: 0.75%); Melting point: 122.13 °C (DSC peak)] .
References
[1] Patent: US2011/34717, 2011, A1. Location in patent: Page/Page column 3
[2] Patent: US2007/173659, 2007, A1. Location in patent: Page/Page column 5
[3] J. Gen. Chem. USSR (Engl. Transl.), 1972, vol. 42, p. 88 - 90
[4] Zhurnal Obshchei Khimii, 1972, vol. 42, p. 93 - 96
[5] Heterocycles, 2011, vol. 83, # 4, p. 743 - 753