Pulse Radiolysis of Alkali Metal Solutions in Methylamine

1975 ◽  
Vol 53 (23) ◽  
pp. 3571-3579 ◽  
Author(s):  
John Wallace Fletcher ◽  
William Arthur Seddon ◽  
John Joseph Jevcak ◽  
Fred Charles Sopchyshyn
Keyword(s):  
Reaction Mechanism ◽  
Alkali Metal ◽  
Reaction Kinetics ◽  
Pulse Radiolysis ◽  
Ion Pairs ◽  
Solvated Electrons ◽  
Extinction Coefficients ◽  
Ion Species ◽  
Triple Ion ◽  
Metal Anions

Pulse radiolysis studies of solutions of alkali metal methylamides (CH3NHM) in methylamine indicate the formation of solvated electrons, es−, ion-pairs (M+, es−), and alkali metal anions M−. This paper compares the spectra, extinction coefficients, and yields of es−, Li, Na, K, and Cs species, with those observed previously in other solvents. The overall reaction kinetics are complex and, in CH3NHNa/NaI solutions, suggest the formation of a higher aggregate or triple ion species (Na22+, es−). A reaction mechanism, quantitatively consistent with experiment, is presented and discussed in detail for solutions containing Na+.

Production of solvated electrons, ion-paris and alkali metal anions in tetrahydrofuran studied by pulse radiolysis

1974 ◽  
Vol 24 (3) ◽  
pp. 366-368 ◽  
Author(s):  
G.A. Salmon ◽  
W.A. Seddon
Keyword(s):  
Alkali Metal ◽  
Pulse Radiolysis ◽  
Solvated Electrons ◽  
Metal Anions

Pulse Radiolytic Formation of Solvated Electrons, Ion-pairs, and Alkali Metal Anions in Tetrahydrofuran

1974 ◽  
Vol 52 (18) ◽  
pp. 3259-3268 ◽  
Author(s):  
G. A. Salmon ◽  
W. A. Seddon ◽  
J. W. Fletcher
Keyword(s):  
Alkali Metal ◽  
Alkali Metals ◽  
Dissociation Constants ◽  
Alkali Metal Cation ◽  
Ion Pairs ◽  
Alkali Metal Cations ◽  
Solvated Electrons ◽  
Sodium Potassium ◽  
Sodium And Potassium ◽  
Metal Anions

Pulse radiolysis of solutions of alkali metal cations in tetrahydrofuran (THF) demonstrates the formation of solvated electrons es−, alkali metal cation-ion pairs (M+, es−), and alkali metal anions M−. This paper describes the spectra, extinction coefficients, and radiolytic yields of es−, lithium, sodium, potassium, and cesium species in THF. The reaction kinetics are complex but largely involve reactions A and B[Formula: see text]with the concomitant disappearance of all three species by reaction with radiolytically produced radicals. Rate constants and ion-pair dissociation constants for es− and the sodium and potassium species are presented and compared with data established from studies of blue solutions of alkali metals dissolved in THF.

Solvated electrons and the effect of coordination on the optical spectra of alkali metal cation – electron pairs in ethers

1977 ◽  
Vol 55 (19) ◽  
pp. 3356-3363 ◽  
Author(s):  
William Arthur Seddon ◽  
John Wallace Fletcher ◽  
Fred Charles Sopchyshyn ◽  
Ron Catterall
Keyword(s):  
Alkali Metal ◽  
Alkali Metal Cation ◽  
Ion Pairs ◽  
Alkali Metal Salts ◽  
Solvated Electrons ◽  
Electron Pairs ◽  
Monomeric Species ◽  
Spin Resonance ◽  
Resonance Data ◽  
Electron Spin Resonance Data

Pulse radiolysis of tetrahydrofuran (THF), dimethoxyethane (DME), diglyme (DG), and triglyme (TG), results in the formation of solvated electrons, es−, with optical band maxima λmax ≥ 1840 nm. In the presence of alkali metal salts transient optical bands are observed with λmax at ∼900 and ≥1600 nm. The latter bands are assigned to the formation of 'monomeric' species of stoichiometry M considered to be 'tight' and 'loose' ion-pairs, respectively. The proportion of 'loose' ion-pairs increases with decreasing temperature and increasing coordination of the solvent in the order [Formula: see text] These results demonstrate a good correlation with established electron spin resonance data in alkali metal solutions and substantiate the coexistence of at least two 'monomeric' species in DME and the glymes.

Pulse Radiolysis of Alkali Metal Solutions in Ethylamine

1973 ◽  
Vol 51 (17) ◽  
pp. 2975-2986 ◽  
Author(s):  
J. W. Fletcher ◽  
W. A. Seddon ◽  
F. C. Sopchyshyn
Keyword(s):  
Alkali Metal ◽  
Pulse Radiolysis ◽  
Electron Pair ◽  
Equilibrium Constants ◽  
Distinct Species ◽  
Complexing Agents ◽  
Crown Compounds ◽  
Solvated Electron ◽  
Sodium Potassium ◽  
Extinction Coefficients

Pulse radiolysis of solutions of alkali metal ethylamides in ethylamine shows the formation of three distinct species; the solvated electron es−, the alkali metal anion M−, and a species considered to be the cation–electron pair with stoichiometry M. The three species coexist in equilibrium in accord with the equations[Formula: see text]Studies of these solutions as a function of temperature, alkali metal concentration, and added complexing agents ("crown" compounds) show that es− and M have distinct absorption spectra with the former having a maximum ≥ 1800 nm. The latter exhibit maxima at 1400 nm for Na and K, ~1400 nm for Cs, and 1600–1700 nm for Li. The corresponding M− species were observed in sodium, potassium, and cesium solutions with absorption maxima at 680, 890, and 1100 nm, respectively.Rate and equilibrium constants for the formation of M and M− vary markedly with the nature of the alkali metal. Estimates for these constants along with the extinction coefficients for the various species are summarized and compared with data obtained in alkali metal solutions.

The effect of temperature on the optical spectra and the yields of solvated electrons and ion-pairs in amines

1978 ◽  
Vol 56 (6) ◽  
pp. 839-843 ◽  
Author(s):  
William Arthur Seddon ◽  
John Wallace Fletcher ◽  
Fred Charles Sopchyshyn
Keyword(s):  
Ion Pairs ◽  
Solvent Polarity ◽  
Solute Concentration ◽  
Ion Pair ◽  
Effect Of Temperature ◽  
Gradual Transition ◽  
Solvated Electron ◽  
Solvated Electrons ◽  
Extinction Coefficients ◽  
Yield Formula

Optical absorption spectra for the solvated electron, es−, and ion-pairs, (Na+, es−), have been observed in methylamine (MA), ethylamine (EA), and isopropylamine (IPA), at temperatures ranging from 184 to 338 K. Changes in the (Na+, es−) spectra, relative to es−, are consistent with a gradual transition in the ion-pair structure toward a more 'electron-like' entity with decreasing temperature and increasing solvent polarity. Extinction coefficients, εmax(es−) = 3.3 ± 0.2, 3.2 ± 0.5, and 3.2 ± 0.5 × 104 M−1 cm−1 in MA, EA, and IPA respectively. Corresponding values for the ion-pairs, εmax(Na+, es−) = 2.5 ± 0.2, 2.1 ± 0.2, and 1.9 ± 0.2 × 104 M−1 cm−1.In EA and IPA, the yield [Formula: see text] (molecules/100 eV) shows a marked solute concentration dependence. This is consistent with an empirical scavenging model from which the escaped solvated G(es−)esc and spur G(es−)spur electrons are estimated as G(es−)esc = 0.5 and 0.4, G(es−)spur = 1.8 and 1.4, giving G(es−)total = 2.3 and 1.8 in EA and IPA, respectively. In MA, [Formula: see text] = G(es−)esc = 2.25 ± 0.2, independent of solute concentration.

The yield and extinction coefficient of the solvated electron in methanol: pulse radiolysis of nitrobenzene and tetranitromethane solutions

1977 ◽  
Vol 55 (11) ◽  
pp. 2030-2043 ◽  
Author(s):  
David W. Johnson ◽  
G. Arthur Salmon
Keyword(s):  
Pulse Radiolysis ◽  
Optical Pulse ◽  
Basic Solution ◽  
Solvated Electron ◽  
Solvated Electrons ◽  
Extinction Coefficients ◽  
Hydroxymethyl Radical ◽  
Direct Measurements ◽  
Wide Range ◽  
Basic Solutions

The radical anion [Formula: see text] NB−, which has a strong absorption spectrum from 250–500 nm, is formed by reaction of nitrobenzene with solvated electrons, es−, and hydroxymethyl radical anions, •CO2O−, with k1 = (1.92 ± 0.35) × 1010 M−1 s−1 and k2 = (1.03 ± 0.02) × 1010 M−1 s−1.[Formula: see text]Gελ is constant for NB− over a wide range of nitrobenzene concentrations in basic solution. By assuming that the yields of scavengeable radicals are the same in neutral and basic solutions we obtain ε(NB−)300 nm = (1.66 ± 0.02) × 104 M−1 cm−1. This value is used to evaluate the yield of es− scavengeable by dilute solutions of solutes as G(es−)esc = 1.20 ± 0.03. Extinction coefficients of es−, hydroxymethyl radicals, •CH2OH, and •CO2O− and the oscillator strength of the es− absorption are calculated.The yields of es− determined by previous workers are discussed in terms of dry, damp, geminate, free, spur, and escaped electrons. A model is constructed in terms of damp, spur, and escaped electrons which compares favourably with experimental scavenging results and direct measurements by optical pulse radiolysis.

The radiation chemistry of organic amides I. A pulse radiolysis study of solvated electrons and alkali-metal-electron species in cyclic amides

1989 ◽  
Vol 421 (1860) ◽  
pp. 169-178 ◽  
Keyword(s):  
Alkali Metal ◽  
Absorption Spectra ◽  
Pulse Radiolysis ◽  
Near Infrared ◽  
Radiation Chemistry ◽  
Alkali Metal Salts ◽  
Solvated Electrons ◽  
Electron Scavenger ◽  
Cyclic Amide ◽  
Metal Electron

Pulse radiolysis of the cyclic amides N -methylpyrrolidinone (NMP), N -ethylpyrrolidinone (NEP), 1,3-dimethyl-2-imidazolidinone (DMI) and 1,3-dimethyl-2-oxo-hexahydropyrimidine (DMH) and the non-cyclic amide tetramethylurea (TMU) yielded absorption spectra in the near infrared that are attributed to solvated electrons. Addition of a variety of alkali-metal salts caused no detectable change in the absorption spectrum of e - s and no new absorptions attributable to alkali-metal anions were detected. The effect of dose on the decay of e - s in NMP was studied in detail. The yields of e - s in these amides were estimated by using trans -stilbene as an electron scavenger. Absorption spectra, which are not removed by saturation with N 2 O and CO 2 , are observed in the wavelength range 300-500 nm.

Flash photolysis of alkali metal anions in tetrahydrofuran and dimethoxyethane

1979 ◽  
Vol 57 (14) ◽  
pp. 1792-1800 ◽  
Author(s):  
W. A. Seddon ◽  
J. W. Fletcher ◽  
F. C. Sopchyshyn ◽  
E. B. Selkirk
Keyword(s):  
Pulse Radiolysis ◽  
Shape Function ◽  
Flash Photolysis ◽  
Ion Pairs ◽  
Ion Pair ◽  
Parent Metal ◽  
Initial Formation ◽  
Extinction Coefficients ◽  
Best Fit ◽  
Good Agreement

Flash photolysis of K−, Rb−, and Cs− in tetrahydrofuran (THF) produces the corresponding ion-pairs (K+, es−), (Rb+, es−), and (Cs+, es−), followed by the regeneration of the parent metal anion, M−. In mixed-metal solutions containing Na and M where M is K, Rb, or Cs, photolysis of Na− also forms the (M+, es−) ion-pair and M−, but with the latter then reforming Na− on an extended time scale. Similar results were obtained in dimethoxyethane (DME) at 213 K, but in this case with the initial formation of a loose ion-pair, (M+, es−)loose.Based on a Gaussian–Lorenztian shape function, the 'best-fit' optical bands for the (M+, es−) and M− species were used to simulate the experimental spectra and deduce the corresponding extinction coefficients in both solvents.The overall mechanism is complex but is in good agreement with previous interpretations deduced by pulse radiolysis.

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