Esters of Lower Phosphorus Oxyacids

Esters of phosphorous acid (phosphonic acid), H3PO3, and hypophosphorous acid (phosphinic acid), H3P02 are dealt with in Chapter 6.7. 

Esters of pyrophosphorous add can be prepared by using sodium dialkyl phosphite and a dialkyl phosphorochloridite (5.321). If a phosphorochloridate ester is used, an ester of hypophosphoric acid is obtained (5.322). 

An alternative synthesis of pyrophosphite esters is by condensation of alkyl phosphorochloridites using water and triethylamine (5.323), while another way of making hypophosphoric esters is by condensation of alkyl phosphorochloridates with sodium (5.324). 

Diazoalkanes react with hypophosphoric or hypophosphorous acids to give hypophosphate or hypophosphite (phosphinic) esters, respectively. 

Esters of lower phosphorus oxo-acids, like those of phosphoric acids, are generally easily hydrolysed by water. 

---