Phosphonite

In organic chemistry, phosphonites are organophosphorus compounds with the formula P(OR)₂R. They are found in some pesticides and are used as ligands.

Although they are derivatives of phosphonous acid (RP(OH)₂), they are not prepared from such precursors. Phosphonites are prepared by alcoholysis of organophosphinous chlorides. For example, treatment of dichlorophenylphosphine with methanol and base gives dimethyl phenylphosphonite:

Cl₂PPh + 2 CH₃OH → (CH₃O)₂PPh + 2 HCl

Oxidation of phosphonites gives phosphonates:

2 P(OR)₂R + O₂ → 2 OP(OR)₂R

Phosphonites can function as ligands in homogeneous catalysis.