The unstable unsymmetrical pyrophosphate diester, P1,P1diethyl pyrophosphate (I), has been synthesized and isolated by photolyzing P1,P1-diethyl-P2-(m-nitrophenyl) pyrophosphate in cold dilute alkali. Compound I rapidly hydrolyzes at pH 7 at room temperature, but it is relatively stable at pH 3. At 35°f-life of the dianion is 10 min, and that of the monoanion is about 500 min. The pKa of the monoanion is 5.2. The rate of hydrolysis of I supports the proposal that its analogs, the unsymmetrically protonated dihydrogen pyrophosphate dianion and the penultimately protonated monoalkyl pyrophosphate dianion, are intermediates in the hydrolysis of dihydrogen pyrophosphate and protonated pyrophosphate monoesters. © 1969, American Chemical Society. All rights reserved.
