13725-27-4Relevant articles and documents
Blukis et al.
, p. 2753,2755 (1963)
Nucleophilic Reactions of Anions with Trimethyl Phosphate in the Gas Phase by Ion Cyclotron Resonance Spectroscopy
Hodges, Ronald V.,Sullivan, S. A.,Beauchamp, J. L.
, p. 935 - 938 (1980)
The gas-phase ion-molecule reactions of several negative ions (SF6-, SF5-, SO2F-, F2-, F-, CF3Cl-, Cl-, CD3O-, DNO-, OH-, and NH2-) with trimethyl phosphate are investigated using ion cyclotron resonance techniques.Nucleophilic attack on OP(OCH3)3 occurs chiefly at carbon, resulting in displacement of O2P(OCH3)2-.This behavior contrast with that observed in solution, where attack at phosphorus is favored for hard nucleophiles.This difference is ascribed to solvation energetics for the intermediates involved in the two reactions.The failure of SF6- to transfer F- to OP(OCH3)3 places an upper limit of 11 +/- 8 kcal/mol on the fluoride affinity of OP(OCH3)3.The significance of the results for the negative chemical ionization mass spectrometry of phosphorus esters is briefly discussed.
Degradation of Organic Cations under Alkaline Conditions
You, Wei,Hugar, Kristina M.,Selhorst, Ryan C.,Treichel, Megan,Peltier, Cheyenne R.,Noonan, Kevin J. T.,Coates, Geoffrey W.
supporting information, p. 254 - 263 (2020/12/23)
Understanding the degradation mechanisms of organic cations under basic conditions is extremely important for the development of durable alkaline energy conversion devices. Cations are key functional groups in alkaline anion exchange membranes (AAEMs), and AAEMs are critical components to conduct hydroxide anions in alkaline fuel cells. Previously, we have established a standard protocol to evaluate cation alkaline stability within KOH/CD3OH solution at 80 °C. Herein, we are using the protocol to compare 26 model compounds, including benzylammonium, tetraalkylammonium, spirocyclicammonium, imidazolium, benzimidazolium, triazolium, pyridinium, guanidinium, and phosphonium cations. The goal is not only to evaluate their degradation rate, but also to identify their degradation pathways and lead to the advancement of cations with improved alkaline stabilities.
Imidazolium Cations with Exceptional Alkaline Stability: A Systematic Study of Structure-Stability Relationships
Hugar, Kristina M.,Kostalik, Henry A.,Coates, Geoffrey W.
supporting information, p. 8730 - 8737 (2015/07/27)
Highly base-stable cationic moieties are a critical component of anion exchange membranes (AEMs) in alkaline fuel cells (AFCs); however, the commonly employed organic cations have limited alkaline stability. To address this problem, we synthesized and characterized the stability of a series of imidazolium cations in 1, 2, or 5 M KOH/CD3OH at 80 °C, systematically evaluating the impact of substitution on chemical stability. The substituent identity at each position of the imidazolium ring has a dramatic effect on the overall cation stability. We report imidazolium cations that have the highest alkaline stabilities reported to date, >99% cation remaining after 30 days in 5 M KOH/CD3OH at 80 °C.
Carbon versus phosphorus site selectivity in the gas-phase anion-molecule reactions of dimethyl methylphosphonate
Lum, Rachel C.,Grabowski, Joseph J.
, p. 7823 - 7832 (2007/10/02)
The reactions of dimethyl methylphosphonate and its conjugate base with a variety of anions and neutral substrates, respectively, have been examined with use of the thermally equilibrated conditions (298 K) of the flowing afterglow. The conjugate base of dimethyl methylphosphonate reacts readily with alcohols and carbonyl compounds; its reaction with alcohols yields products from proton transfer, proton transfer followed by substitution at carbon, and proton transfer followed by substitution at phosphorus, while its reaction with carbonyl compounds generates products from proton transfer, Horner-Emmons-Wadsworth reaction, addition/elimination, and adduct formation. Dimethyl methylphosphonate undergoes facile reaction with a diverse set of anions ranging in base strength from amide to hydrogen sulfide and in structure from localized heteroatomic bases and localized carbon bases to delocalized carbanions. Four reaction pathways account for the interaction of anions with dimethyl methylphosphonate: proton transfer, nucleophilic substitution at carbon, reductive elimination, and nucleophilic substitution at phosphorus. Proton transfer and nucleophilic substitution at carbon dominate all reactions, while reductive elimination is observed only for the strongest base examined, amide. Methoxide and fluoride are the only anions that react at phosphorus. A reaction coordinate diagram is used to interpret the reactions of dimethyl methylphosphonate and its conjugate base. The acidity of dimethyl methylphosphonate was bracketed to be ΔHoacid[(CH3O)2(CH 3)PO] = 373 ± 3 kcal mol-1.