[CH2:1]([P:3]([CH2:6][CH2:7][OH:8])(=[O:5])[OH:4])[CH3:2].CC(C)=[O:11].OS(O)(=O)=O.O=[Cr](=O)=O.C(O)(C)C>CC(C)=O>[CH2:1]([P:3]([OH:4])([CH2:6][C:7]([OH:11])=[O:8])=[O:5])[CH3:2]13.8 g (0.1 mol) of ethyl-(2-hydroxyethyl)phosphinic acid (produced as in Example 8) in 500 ml of acetone were admixed with 0.11 mol of Jones reagent (12.7 g of chromium trioxide in 36.7 ml of water and 11.0 ml of concentrated sulfuric acid) at 0° C. by dropwise addition. The reaction mixture was additionally stirred for 3½ hours with ice cooling and for 1 hour at room temperature. After 12 ml of isopropanol have been added, the mixture is poured onto ice-water. Volatile constituents are subsequently distilled off in vacuo. The residue was taken up in tetrahydrofuran and extracted. Insoluble salts were filtered off. The solvent of the filtrate was removed in vacuo and the residue was recrystallized from acetone to obtain 12.3 g (81% of theory) of 2-(ethylhydroxyphosphinyl)acetic acid as colorless solid.
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