1623-14-9Relevant articles and documents
Balarew
, p. 226 (1917)
Biomimetically activated amino acids. Catalysis in the hydrolysis of alanyl ethyl phosphate
Kluger, Ronald,Loo, Richard W.,Mazza, Vince
, p. 12089 - 12094 (1997)
Alanyl ethyl phosphate (1) is an activated derivative of alanine that is functionally related to the corresponding aminoacyl adenylate, the initial activated amino acid intermediate in protein biosynthesis. To establish the inherent reactivity of these species, the kinetic parameters for hydrolysis of alanyl ethyl phosphate in water at 25 °C were determined. There is catalysis by acid (k = 4 x 10-4 M-1s-1) and base (k = 1.7 M-1 s-1) along with two pH-independent processes (k = 3 x 10-5 and 1.6 x 10-3 s- 1) that are connected as a kinetic titration curve of the amino group of alanyl ethyl phosphate (pK(a) = 7.8). The results are consistent with mechanisms proceeding via addition to the carbonyl of water or hydroxide with proton migrations. Reaction with methanol is slower than reactions with water while reaction with 2-propanol leads to complex products. In solutions sufficiently concentrated for 31P NMR analysis, alanyl ethyl phosphate also undergoes reactions that produce alanylalanine and other condensation products. Metal ions catalyze the hydrolysis reactions through complex formation. Cupric and zinc ions are most effective (~100-fold larger rate constant than water: association constants > 100 M-1) with magnesium and calcium forming weaker and less reactive complexes. These results show that aminoacyl alkyl phosphates are sufficiently stable to be used in water and that metal ions can facilitate their reactions. Improved catalysts will be needed to facilitate biomimetic processes such as aminoacylation of t-RNA.
Kugel,Halmann
, p. 642,646 (1967)
Pathways for the Reactions Between Neurotoxic Organophosphorus Compounds and Oximes or Hydroxamic Acids
Bierwisch, Anne,Koller, Marianne,Worek, Franz,Kubik, Stefan
, p. 5831 - 5838 (2016)
To obtain mechanistic insight into the recently demonstrated detoxification ability of β-cyclodextrin derivatives containing substituents with oxime or hydroxamic acid residues, analogous glucose derivatives with the same substituents were treated with cyclosarin (GF), tabun (GA), and O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate (VX) in (Tris)-HCl buffer (0.1 m, pH 7.40), and the different reaction pathways were studied by31P NMR spectroscopy and mass spectrometry. Consistent with previous reports, the oxime is phosphonylated by GF, which is followed by elimination of O-cyclohexyl methylphosphonate to afford a nitrile. Reaction of the hydroxamic acid with GA depends on whether the nitrogen atom of the hydroxamic acid bears a substituent or not. The unsubstituted hydroxamic acid affords a stable phosphate ester lacking the cyanide and the dimethylamino group of GA. If the hydroxamic acid is methylated, the initially formed phosphorylated product undergoes a number of transformations, including cleavage of the C–N bond of the hydroxamic acid. Reaction of the hydroxamic acid with VX involves a Lossen rearrangement. These investigations thus show that all investigated nucleophiles are irreversibly modified upon reaction with nerve agents under the chosen conditions, which indicates that cyclodextrins with oximes or hydroxamic acid as substituents are unlikely to afford catalytic nerve-agent scavengers.
Wet and dry processes for the selective transformation of phosphonates to phosphonic acids catalyzed by br?nsted acids
Li, Chunya,Saga, Yuta,Onozawa, Shun-Ya,Kobayashi, Shu,Sato, Kazuhiko,Fukaya, Norihisa,Han, Li-Biao
, p. 14411 - 14419 (2020/12/29)
A "wet"process and two "dry"processes for converting phosphonate esters to phosphonic acids catalyzed by a Bronsted acid have been developed. Thus, in the presence of water, a range of alkyl-, alkenyl-, and aryl-substituted phosphonates can be generally hydrolyzed to the corresponding phosphonic acids in good yields catalyzed by trifluoromethyl sulfonic acid (TfOH) at 140 °C (the wet process). On the other hand, with specific substituents of the phosphonate esters, the conversion to the corresponding phosphonic acids can be achieved under milder conditions in the absence of water (the dry process). Thus, the conversion of dibenzyl phosphonates to the corresponding phosphonic acids took place smoothly at 80 °C in toluene or benzene in high yields. Moreover, selective conversion of benzyl phosphonates RP(O)(OR′)(OBn) to the corresponding mono phosphonic acids RP(O)(OR′)(OH) can also be achieved under the reaction conditions. The dealkylation via the generation of isobutene of ditert- butyl phosphonate, and the related catalysis by TfOH took place even at room temperature to give the corresponding phosphonic acids in good to high yields. Nafion also shows high catalytic activity for these reactions. By using Nafion as the catalyst, phosphonic acids could be easily prepared on a large scale via a simple process.
An Unusual Two-Step Hydrolysis of Nerve Agents by a Nanozyme
Khulbe, Kritika,Roy, Punarbasu,Radhakrishnan, Anusree,Mugesh, Govindasamy
, p. 4840 - 4845 (2018/09/27)
Organophosphate-based nerve agents irreversibly inhibit acetylcholinesterase enzyme, leading to respiratory failure, paralysis and death. Several organophosphorus hydrolases are capable of degrading nerve agents including pesticides and insecticides. Development of stable artificial enzymes capable of hydrolysing nerve agents is important for the degradation of environmentally toxic organophosphates. Herein, we describe a Zr-incorporated CeO2 nanocatalyst that can be used for an efficient capture and hydrolysis of nerve agents such as methyl paraoxon to less toxic monoesters. This unusual sequential degradation pathway involves a covalently linked nanocatalyst-phosphodiester intermediate.
