Phosphate methyl

Place 28 g. (27-5 ml.) of pure aniline and 28 g. (23 ml.) of purified methyl phosphate in a 500 ml. round-bottomed flask equipped with a reflux condenser. Heat gently at first and remove the flame when the vigorous and exothermic reaction commences. When the latter subsides. 

Fmoc chemistry is compatible with methyl phosphates when methanolic... 

Dimethyl sulfide, CH3SO3H. Methyl phosphates are selectively cleaved in the presence of other alkyl phosphates. ... 

Problem 2.9 Organic phosphate groups occur commonly in biological molecules. Calculate formal charges on the four O atoms in the methyl phosphate dianion. 

Strain NRC-525-17 (Canada, Saskatchewan) Anatoxin-A(S) N-hydvoxy guanidine methyl-phosphate ester, MW 252 20... 

Pyrolysis of the phosphorodichloridothioate (59) at 550 °C gives mainly dibenzothiophen and a smaller amount of the cyclic phosphonochlorido-thioate (60). Thermal decomposition of di-t-butyl peroxide in triethyl phosphate gives rise to diethyl methyl phosphate in a reaction which may be interpreted as resulting from attack of methyl radical on the phosphoryl oxygen. An extension of this mechanism accounts for the formation of (61) from tri-isopropyl phosphate under the same conditions. 

The factors involved and mechanistic pathways in the hydrolysis of phosphate esters, particularly those of a cyclic nature, continue to be the source of much speculation. A further study of the simplest cyclic triester, ethylene methyl phosphate, seems only to have served to consolidate already polarized views. The original, experiments of Westheimer s group employed gc and H nmr spectroscopy and demonstrated that ethylene methyl phosphate (26) hydrolyses under alkaline conditions by... 

There has been controversy over the mechanism of hydrolysis of ethylene methyl phosphate and investigations into the nature of metaphosphate and its role in the hydrolysis of phosphorus esters have continued. Elegant experiments relating to each of these problems have been reported. 

C2sH44Nia018P2Pt ll H20 Trimethylenediamine-bis[guanosine 5 -(methyl phosphate)]platinum(II), undecahydrate (ENGUME)215... 

CioH NjOgP" Na+CH40 2,3-O-Sodiouridine 5 -(methyl phosphate), methanolate SUROMM 38 510... 

As is apparent from Fig. 1, the dianions of monoalkyl phosphates normally resist hydrolysis. However, for leaving groups whose conjugate acids exhibit a pKa < 5 in water, hydrolysis of the dianion becomes faster than that of the monoanion. Fig. 2 shows a pH profile characteristic of this situation. Whereas the hydrolysis rate of 2,4,6-trichlorophenyl phosphate (pKa of the phenol 6.1) still shows the typical monoanion preference as seen for methyl phosphates (Fig. 1), the dianion of 2,4-dinitrophenyl phosphate (pKa of the phenol 4.09) is hydrolyzed far faster than the monoanion 2-chloro-4-nitrophenyl phosphate represents an intermediate case (pKa of the phenol 5.45)6S). 

Photochemical fragmentation 165 166+167 is also feasible. Isopropyl phosphate and isopropyl methyl phosphate are expectedly found after reaction of the photolysis solution with water or methanol. It would appear that 166 (and possibly also 167) can arise directly from 164 and not only by photochemical cycloreversion of 165 since 166 is formed together with 165 even at wavelengths in the range where 165 is known to be stable. 

Fig. 9.7. a) Mechanism of activation of (phenytoin-3-yl)methyl phosphate (9.25) to release phenytoin. Phosphoric acid ester hydrolysis is mediated by alkaline phosphatase, b) (Phospho-ryloxy)methyl prodrugs of tertiary amines, whose activation occurs by the same two-step mechanism shown in a [79]. 

---