Organic Phosphorus Compounds 61. Esterification and chlorination of nitrilo‐tri(methylene‐phosphonic acid), N(CH2PO3H2)3, and hydroxyethylidenediphosphonic acid, H2O3PC(OH)(CH3)PO3H2, and the corresponding esters

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Abstract
Nitrilo‐tri(methylenephosphonic acid) and hydroxyethylidenediphosphonic acid are esterified in high yield when treated with excess orthoformic acid ester under reflux. Because of the high temperature necessary to effect esterification a partial isomerization of hydroxyethylidenediphosphonate to the phosphate‐phosphonate isomer V takes place. Chlorination of N(CH2PO3H2)3 or a mixture of the ester and the acid with PCl5 yields tris(chloromethyl)amine, N(CH2Cl)3. Interaction of N(CH2Cl)3 and (EtO)3P yields nitrilo‐tri(methylenephosphonate), which on hydrolysis with HCl conc. produces N(CH2PO3H2)3. Chlorination of a mixture of hydroxyethylidene‐diphosphonic acid and the corresponding ethyl ester IV which contained the phosphate‐phosphonate isomer V gave the products VII to XI. Chlorination of the acid III with PCl5 gave 4 products, i.e., VIII, IX, XI and Cl2(O)POP(O)Cl2. The 1H‐ and 31P‐NMR. spectra of the products are discussed.