1,4-Dibromobenzene → Tetraethyl 1,4-phenylenebisphosphonate

Participants

Reaction Conditions

Reaction Steps

10 g (42 mmoles) of 1,4-dibromo-benzene and 600 mg of anhydrous NiCl2 are placed in a two-necked 250 ml flask which has a cooler, dripper funnel and magnetic agitation. 17.6 ml (100 mmoles) of triethyl-phosphite are added to the mixture dropwise and heated to 170° C. in an oil bath. The mixture is left under agitation at 170° C. for 2 hours, it is then cooled to 100° C. and subjected to vacuum distillation (1 mm Hg) to eliminate the excess triethyl-phosphite. The residue solubilized in 10 ml of ethanol undergoes chromatography on a silica column (5×56 cm) eluting first with 4 liters of a 95:5 ethyl-acetate/ethanol mixture and then with 3 liters of a 90:10 ethyl-acetate/ethanol mixture. 6.0 g (17.4 mmoles) of 1,4-benzene-diphosphonic acid tetra-ethyl ester are obtained with a molar yield of 41%.

Provenance & Evidence