THE CONDENSATION OF PHOSPHONOTHIOIC AND PHOSPHONIC DICHLORIDES WITH o-DIAMINES

A series of 2,3-dihydro-1H-1,3,2-benzodiazaphosphole 2-sulfides and 2-oxides have been prepared, most commonly by the condensation of a diamine with a phosphonothioic or phosphonic dichloride in a refluxing inert solvent. The phosphonothioic dichlorides react more slowly than the corresponding phosphonic dichlorides, and phenylenediamines containing electron-donating substituents are more reactive than those containing electron-withdrawing substituents. The diazaphosphole 2-oxides undergo hydrolysis or alcoholysis of only one of the amide groups under mild conditions. The 2-sulfides are much more resistant to hydrolysis than the 2-oxides. The 2-sulfides are converted to the N-methyl derivatives by dimethyl sulfate and alkali. The 2-oxides are hydrolyzed under these conditions. The 2-sulfides are invariably lower melting and more soluble in nonpolar solvents than their 2-oxide analogues.