OXYPHOSPHORANE AND MONOMERIC META-PHOSPHATE ION INTERMEDIATES IN PHOSPHORYL TRANSFER FROM 2,4-DINITROPHENYL PHOSPHATE IN APROTIC AND PROTIC SOLVENTS

The reactions of 2, 4-dinitrophenyl dihydrogen phosphate, ArPH2, and of salts of type (ArPH)-R4N)+, (ArPH)-(R3NH)+, (ArP)2-(R4N)+(R3NH)+, and (ArP)2-2(R3NH)+, where R4N+ = (n-C4H9)4N+ and R3N = (i--C3H7)2C2H5N, have been studied in aprotic and protic solvents, in the absence and in the presence of alcohols or water, ROH, following the release of phenol and the fate of the phosphorus. The results are interpreted as follows. (1) The acid and the monoanion react via oxyphosphorane intermediates, P(5). (2) The dianion reacts via a monomeric metaphosphate ion intermediate, PO3-. In the absence of ROH, acid, monoanion, and dianion generate cyclic trimetaphosphoric acid or its salts, (CP3)3- in aprotic solvents. Phosphoryl transfer to ROH by the P(5) mechanism proceeds at a relatively slow rate, the rate depends on alcohol size, and the reaction does not generate tert-butyl phosphate from tert-butyl alcohol. Rates are faster ana independent of alcohol size, and tert-butyl phosphate is formed from tert-butyl alcohol by the PO3- mechanism. Formation of (CP3)3- is not an indication of PO3- intermediacy in phosphorylation. The conclusions are limited to aminium salts of ArPH2where the amine is sterically hindered. © 1979, American Chemical Society. All rights reserved.