Hydroxylamine Anion as a Strong Acceptor of Acyl Groups

Simanenko, Yurii S.; Popov, A. F.; Prokop’eva, T. M.; Savëlova, V. A.; Belousova, І. A.; Zubareva, T. M.

doi:10.1070/mc1994v004n06abeh000417

Cited by 9 publications

(4 citation statements)

References 9 publications

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“…The strong inhibition of the initial reactions by O-methylation confirms the original assumption that attack on phosphorus is preferentially by the OH group, although there is a slow reaction with NH 2 OMe forming the N -phosphorylated derivative 8 and DNP (Scheme ). Deprotonation of NHMeOH and NMe 2 OH at high pH generates oxide anions, which like NH 2 O - should be very effective dephosphorylating agents, and we assume that the increases in observed first-order rate constants with increasing pH involve this intervention. Values of the first p K a are known for the methylated hydroxylamines (Table ), and the second p K a of NH 2 OH is 13.74 .…”

Section: Resultsmentioning

confidence: 99%

Mechanisms of Nucleophilic Substitution Reactions of Methylated Hydroxylamines with Bis(2,4-dinitrophenyl)phosphate. Mass Spectrometric Identification of Key Intermediates

et al. 2004

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Mono- and dimethylation of hydroxylamine on nitrogen does not significantly affect rates of initial attack of NHMeOH and NMe(2)OH on bis(2,4-dinitrophenyl)phosphate (BDNPP), which is largely by oxygen phosphorylation. O-Methylation, however, blocks this reaction and NH(2)OMe then slowly reacts with BDNPP via N-attack at phosphorus and at the aryl group. With NHMeOH, the initial product of O-attack at phosphorus reacts further, either by reaction with a second NHMeOH or by a spontaneous shift of NHMe to the aryl group via a transient cyclic intermediate. There is a minor N-attack of NHMeOH on BDNPP in an S(N)2(Ar) reaction. Reactions occurring via N-attack are blocked by N-dimethylation, and reaction of NMe(2)OH with BDNPP occurs via O-attack, generating a long-lived product. Reaction mechanisms have been probed, and intermediates identified, by using both NMR and MS spectroscopy, with the novel interception of key reaction intermediates in the course of reaction by electrospray ionization mass and tandem mass spectrometry.

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Section: Resultsmentioning

confidence: 99%

Mechanisms of Nucleophilic Substitution Reactions of Methylated Hydroxylamines with Bis(2,4-dinitrophenyl)phosphate. Mass Spectrometric Identification of Key Intermediates

et al. 2004

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“…Most of our work was in the pH range 4−12 (should this be, 10 k increases at pH > 10) where nonionic hydroxylamine is dominant and the spontaneous hydrolysis of BDNPP is slow . At high pH NH 2 O - (p K a = 13.74) is a very strong nucleophile, but we did not investigate reaction products in detail at high pH because of the instability of the organic products in basic solutions.…”

Section: Introductionmentioning

confidence: 99%

Reactions of Bis(2,4-dinitrophenyl) Phosphate with Hydroxylamine

et al. 2003

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For dephosphorylation of bis(2,4-dinitrophenyl) phosphate (BDNPP) by hydroxylamine in water, pH region 4-12, the observed first-order rate constant, k(obs), initially increases as a function of pH, but is pH-independent between pH 7.2 and pH 10. The initial BDNPP cleavage by nonionic NH(2)OH (<0.2 M) involves attack by the OH group and follows first-order kinetics, but the overall initial reaction of BDNPP liberates ca. 1.7 mol of 2,4-dinitrophenoxide ion (DNP). This initial reaction generates a short-lived O-phosphorylated hydroxylamine, 2, followed by three possible reactions: (1) reaction of 2 with hydroxylamine, generating 2,4-dinitrophenyl phosphate (DNPP, 3), which subsequently forms DNP; (2) intramolecular displacement of the second DNP group and rapid decomposition of the cyclic intermediate to form phosphonohydroxylamine and eventually inorganic phosphate; (3) a novel rearrangement with intramolecular aromatic nucleophilic substitution involving a cyclic intermediate and migration of the 2,4-dinitrophenyl group from O to N. Values of k(obs) increase modestly with pH > 10, the reaction is biphasic, and the yield of DNP increases. An increase in [NH(2)OH] also increases the yield of DNP, due largely to accelerated hydrolysis of DNPP.

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“…Finally at pH > 10 a further increase in the rate of reaction occurs. This pH profile is similar to the reactions of hydroxylamine with 4-nitrophenyl esters of acetic acid, diethylphosphonic acid, diethylphosphoric acid, 4-toluenesulfonic acid, and N,N-dimethylcarbamic acid [3,4]. The nucleophilic reactivity of the neutral forms of N-MeHA and N,N-(Me) 2 HA (k HA w ) can be found from any point of the plateau in the range of the pH-independent transfer of the phosphonyl groups ( Fig.…”

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confidence: 74%

Reactivity of N-alkyl derivatives of hydroxylamine in decomposition of 4-nitrophenyl diethylphosphonate in water and in cetyltrimethylammonium bromide micelles

et al. 2007

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Neutral forms of hydroxylamine, N-methylhydroxylamine, and N,N-dimethylhydroxylamine are typical a-nucleophiles in water. In comparison with aryl anions of similar basicity their rate of reaction in the decomposition of 4-nitrophenyl diethylphosphonate is increased by about 10 2 times. Decomposition of the substrate is accelerated in cetyltrimethylammonium bromide micelles (about 4 to 30 fold). Hydroxylamine and its N-alkyl derivatives are the most effective low basicity nucleophiles. The sole factor responsible for the micellar effects is the concentration of the reagent in the surfactant micelles.Hydroxylamine (HA) is a unique a-nucleophile: its neutral and anionic forms are particularly effective decomposers of acyl compounds as substrates, including extremely toxic phosphate esters, over a wide range of acidic media (pH ³ 6.0) [1-4]. In particular, the anion of hydroxylamine is the "leader" among a-nucleophiles in nucleophilic substitution reactions with electron-poor centers -carbon, phosphorus, sulfur -and its reactivity is close to the limit for a-nucleophiles. N-Alkylhydroxylamines -N-methyl-and N,N-dimethylhydroxylamines (N-MeHA and N,N-(Me) 2 HA) are also typical a-nucleophiles. In fact, in reactions with an activated ester -bis(2,4-dinitrophenyl) phosphate -HA, N-MeHA, and N,N-(Me) 2 HA have anomalously high reactivity (³10 times faster than O-methylhydroxylamine) [1,2]. Nevertheless, it is not evident that the a-effect and the order of change in nucleophilicity of HA and its N-alkyl derivatives would remain the same with less reactive substrates. With the objective of constructing a system for the destruction of ecotoxicants it is necessary to take into account a whole range of factors, including solubility in water. One method for increasing the solubilization of organophosphorus compounds (OPC) is to carry out reactions in aqueous solutions of surface-active substances. The correct choice of surfactant -cationic, neutral, or anionic -for decomposition of OPC should lead to an increase in the observed rate of reaction.In the present work the reactivity of neutral forms N-methylhydroxylamine and N,N-dimethylhydroxylamine in water and hydroxylamine, N-methylhydroxylamine, and N,N-dimethylhydroxylamine in the presence of a cationic surfactant -0040-5760/07/4304-0247

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Hydroxylamine Anion as a Strong Acceptor of Acyl Groups

Cited by 9 publications

References 9 publications

Mechanisms of Nucleophilic Substitution Reactions of Methylated Hydroxylamines with Bis(2,4-dinitrophenyl)phosphate. Mass Spectrometric Identification of Key Intermediates

Mechanisms of Nucleophilic Substitution Reactions of Methylated Hydroxylamines with Bis(2,4-dinitrophenyl)phosphate. Mass Spectrometric Identification of Key Intermediates

Reactions of Bis(2,4-dinitrophenyl) Phosphate with Hydroxylamine

Reactivity of N-alkyl derivatives of hydroxylamine in decomposition of 4-nitrophenyl diethylphosphonate in water and in cetyltrimethylammonium bromide micelles

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