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A powder containing sorptive and reactive resins that was developed for the removal and subsequent catalytic degradation of toxic organophosphorus esters is characterized using dimethyl methylphosphonate (DMMP), p-nitrophenyl diphenylphosphate (PNDP), and 31P MAS NMR. The results for DMMP confirm, spectroscopically, that the adsorbed ester is distributed between the sorptive and reactive resin components. Spectra of the DMMP surface probe adsorbed on the resin are indicative of two different adsorption sites, one possessing a much larger capacity compared with the other. The large-capacity site is identified as the sorptive macroreticular ‘porous’ region of the resin. The smaller-capacity site seems to be associated with the reactive quaternary ammonium hydroxide functional groups of the ion-exchange resin. At each type of site, adsorbed DMMP exhibits ‘liquid-like’ isotropic motion; however, the molecules do not appear to be able to rapidly migrate between the sorptive and reactive regions. Variable-temperature 31P MAS NMR results for DMMP demonstrate that any molecular exchange between these sites must be occurring at a rate of less than 300 s−1, even at 50 °C. PNDP hydrolyzes on the resin powder to yield diphenyl phosphate (DPP) and p-nitrophenoxide. A second 31P MAS NMR resonance is not observed for PNDP adsorbed at the reactive sites; however, the anionic DPP product appears to be tightly bound by the quaternary amine ion-exchange group, which may block further PNDP hydrolysis at the reactive site.

The tertiary amine, N -2-hydroxyethylpiperazine- N '-2-ethanesulfonic acid (HEPES) is a common buffer used in measuring the hydrolysis of neurotoxins such as the phosphonofluoridates soman and sarin. The hydrolysis of soman was monitored in the presence of various concentrations of HEPES at 25 °C and pH= 7. The rate of hydrolysis of soman was linearly related to the concentration of HEPES present as free base in solution. The second-order rate for the HEPES catalysis was 1.6 × 10 −3 M −1 s −1 , in contrast to a value of 10 M −1 s −1 for the hydroxide ion-catalyzed nucleophilic attack on soman.

Neat droplets of O,O-diisopropylphosphorofluoridate (DFP) and O-1,2,2-trimethylpropyl methylphosphonofluoridate (Soman) decompose on glass. In thirty hours at room temperature over 40% of the Soman has been decomposed while nearly 15% of the DFP has been degraded. NMR spectroscopic analysis of the Soman showed that Soman decomposed exclusively by scission of the PF bond to form O-1,2,2-trimethylpropyl methylphosphonic acid. The rate of decomposition of the two organophosphorus fluorine substrates is proportional to the rate of hydrolysis. The results are consistent with earlier studies which showed that silica or magnesia promoted the decomposition of sarin (O-2-propylisopropyl methylphosphonofluoridate). The rate of decomposition on glass is accelerated in the presence of high humidity.

The syntheses of five new 4-alkyl-2-iodosobenzoic acids (3) are described. The iodine atom was introduced by ortho-directed lithiation of 4-alkylbenzyl alcohols followed by treatment with I 2 . The catalytic effectiveness of each of the products in the hydrolysis of 4-nitrophenyl diphenyl phosphate in microemulsions was studied. The 4-methyl- and 4-ethyl-substituted products were each found to be significantly better catalysts than the standard nonalkylated 2-iodosobenzoic acid (3, R = H). These results would indicate that microemulsions of these materials may find use in detoxification procedures

Organophosphonofluoridates [CH 3 (OR)P(O)F] are potent neurotoxins. In aqueous solutions these compounds hydrolyze to release fluoride and form the corresponding O -alkyl methylphosphonic acid. Recently we examined the hydrolysis of O -isopropyl t -butylphosphonofluoridate ( I ) which was reputed to be relatively nontoxic relative to O -isopropyl methylphosphonofluoridate (sarin). The hydrolysis of I was measured with 31 P NMR at 20°C in buffered solutions with pH values of 4.0, 7.2, 9.2, and 10.0, respectively. At pH 10, I hydrolyzed approximately 4000 times slower than sarin. In addition I hydrolyzed by parallel reaction paths producing both O -isopropyl t -butylphosphonic acid and t -butylphosphonofluoridic acid. Below pH 9, the latter product predominates. To our knowledge this is the first example of parallel hydrolysis paths above pH 7 for a phosphonofluoridate.

Transition metal ions, such as manganese(II) or copper(II), catalyze the hydrolysis of O -isopropyl methylphosphonofluoridate (sarin) or O , O' -diisopropyl phosphorofluoridate (DFP). The rate law for the catalyzed path is first order in ester, metal(II) and hydroxide. Thus, the catalytic species could be the hydroxometal complex, or the catalysis could consist of a complex formed between the metal ion and phosphorus substrate which is subsequently attacked by hydroxide. Recently, we measured the solvolysis of sarin in an ethanol-water solution. By means of 31 P nuclear magnetic resonance (NMR), two products were seen to form from parallel attack on sarin by hydroxide and ethoxide. In the presence of zinc(II) chloride, it was shown that both reaction rates were significantly increased. If the increase in reactivity were attributed to a zinc hydroxide complex, then no change would be expected in the rate of attack by ethoxide ion. We further suggest the monitoring of relative rates of reaction in mixed solvents as a way to distinguish whether a metal ion catalyst acts as a Lewis acid or simply supplies a larger concentration of nucleophilic hydroxide ion.

Mustard, bis-(2-chloroethyl) sulfide, hydrolyzes to form the mustard chlorohydrin with concomitant loss of chloride; the chlorohydrin subsequently hydrolyzes to form the mustard diglycol with loss of another chloride ion. The kinetics of these reactions constitutes two consecutive, irreversible reactions. Past investigators approximated the hydrolysis as a single, first-order reaction from which an activation energy was determined. Bartlett and Swain measured the rate of mustard chlorohydrin hydrolysis after which they could determine the rate of mustard hydrolysis with a graphical method. Bartlett and Swain performed their experiments at 25°C, so no activation parameters were measured. A non-linear least-squares program was modified to fit consecutive, irreversible first-order kinetics and refit original data for mustard hydrolysis in order to find activation parameters for each step. The data failed to conform to consecutive, first-order kinetics suggesting that either sampling error or failure to dissolve rapidly interfered with the kinetics. Thus, the activation parameters for mustard hydrolysis are incorrect not only for the single-step approximation, but also because systematic experimental errors must be present. Rate coefficients computed with Bartlett and Swain's data were statistically equivalent to their reported value of 0.155 min −1 .

The kinetics of the hydrolysis of 1,2-2-trimethylpropyl methylphosphonofluoridate (soman) was measured from 1 to 80 × 10−5 m hydroxide-ion concentration. No apparent “saturation effect” could be positively identified such as was reported by Martell for the hydrolysis of isopropyl methylphosphonofluoridate (sarin). The second-order rate coefficient for soman was 10.0 ± 0.03 m −1 s−1 at 25.0°C over this pH range.

Hydrolyse du sulfure d'ethyle et de chloro-2 ethyle et du sulfure de methyle et de chloro-2 ethyle. Comparaison a l'hydrolyse du chlorure de t-butyle. Mise en evidence d'un mecanisme S N 1 avec assistance anchimere de l'atome de soufre pour former un ion sulfonium cyclique comme intermediaire de reaction

Hydrolyse des bis-[chloro-2 ethyl] sulfure, chloro-2' ethylthio-2 ethanol en presence de thio-2,2' bis-ethanol. Identification par les spectres RMN 13 C des composes sulfonium obtenus