ORGANIC PHOSPHORUS COMPOUNDS 90.l A CONVENIENT, ONE-STEP SYNTHESIS OF ALKYL- AND ARYLPHOSPHONYL DICHLORIDES

N,N-Disubstituted formamides such as dimethylformamide. N-formylpyrrolidine, N-formylpiperidine etc. and also pyridine and hexamethylphosphonic acid triamide catalyze the chlorination of phosphonates with thionyl chloride to give phosphonyl dichlorides in high yield. Thus RP(O)CI2, R ˭ CH3, C2H5, n-C12H25, C6H5, have been isolated in better than 90 per cent yield. The procedure is less satisfactory for the production of 2-chloroethylphosphonyl dichloride. Only a 34 per cent yield was realized. The chlorination proceeds very likely through the intermediate formation of the halfesters, RP(O)(OR)CI since these could be isolated under favorable circumstances.