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Dimethylaminophosphorus dichloride

Dimethylaminophosphorus dichloride is an organophosphorus compound with the formula Me<sub>2</sub>NPCl<sub>2</sub> (Me = methyl). A colorless liquid, it is a reagent in the preparation of other organophosphorus compounds. Many analogous compounds can be prepared from the reactions of secondary amines and phosphorus trichloride:

2 R<sub>2</sub>NH + PCl<sub>3</sub> → R<sub>2</sub>NPCl<sub>2</sub> + R<sub>2</sub>NH<sub>2</sub>Cl

Reactions

Further equivalents of amine react with dialkylaminophosphorus dichlorides:

2 R<sub>2</sub>NH + R<sub>2</sub>NPCl<sub>2</sub> → (R<sub>2</sub>N)<sub>2</sub>PCl + R<sub>2</sub>NH<sub>2</sub>Cl

Since the P-NR<sub>2</sub> bond is not attacked by Grignard reagents, dimethylaminophosphorus dichloride can be selectively dimethylated:

2 MeMgBr + Me<sub>2</sub>NPCl<sub>2</sub> → Me<sub>2</sub>NPMe<sub>2</sub> + 2 MgBrCl

The resulting dimethylphosphino derivative, a structural relative of tetramethylhydrazine, reacts with hydrogen chloride to give chlorodimethylphosphine:

Me<sub>2</sub>NPMe<sub>2</sub> + 2 HCl → ClPMe<sub>2</sub> + Me<sub>2</sub>NH<sub>2</sub>Cl

References