Preparation method of 4-(hydroxymethylphosphonyl)-2-oxobutyric acid

The invention provides a preparation method of 4-(hydroxymethylphosphonyl)-2-oxobutyric acid, which comprises the following steps: a) mixing methyl phosphonite monoester, a solvent, an initiator and acryloyl cyanide, carrying out addition reaction, and carrying out reduced pressure distillation to obtain (3-cyano-3-carbonyl propyl) methyl phosphonate feed liquid; and b) uniformly mixing the (3-cyano-3-carbonyl propyl) methylphosphonate feed liquid obtained in the step a) with water, cooling to 10-40 DEG C, dropwise adding hydrochloric acid for acidification, continuously stirring for 0.1-1 hour after dropwise adding, then carrying out hydrolysis reaction, and finally carrying out purification treatment to obtain the 4-(hydroxymethylphosphonyl)-2-carbonyl butyric acid. Compared with the prior art, the preparation method provided by the invention does not need a cyanidation reaction, avoids the use of high-cost and difficult-to-obtain cyclophosphinic anhydride and highly toxic sodium cyanide, and has the advant