stylistic:style_transfer, structural:expansion
Phosphonic and phosphinic acids and their esters

Phosphonates are esters of phosphonic acid and have the general formula RP(=O)(OR'). Phosphonates have many technical applications, a well-known member being glyphosate, better known as Roundup. With the formula (HO) P(O)CH NHCH CO H, this derivative of glycine is one of the most widely used herbicides. Bisphosphonates are a class of drugs to treat osteoporosis. The nerve gas agent sarin, containing both C–P and F–P bonds, is a phosphonate.

Phosphinates feature two P–C bonds, with the general formula R P(=O)(OR'). A commercially significant member is the herbicide glufosinate. Similar to glyphosate mentioned above, it has the structure CH P(O)(OH)CH CH CH(NH)CO H.

The Michaelis–Arbuzov reaction is the main method for the synthesis of these compounds. For example, dimethylmethylphosphonate (see figure above) arises from the rearrangement of trimethylphosphite, which is catalyzed by methyl iodide. In the Horner–Wadsworth–Emmons reaction and the Seyferth–Gilbert homologation, phosphonates are used in reactions with carbonyl compounds. The Kabachnik–Fields reaction is a method for the preparation of aminophosphonates. These compounds contain a very inert bond between phosphorus and carbon. Consequently, they hydrolyze to give phosphonic and phosphinic acid derivatives, but not phosphate.