Spectrum, Kinetics, and Radiation Chemical Yield of Solvated Electrons in Hexamethylphosphoric Triamide

1973 ◽  
Vol 51 (23) ◽  
pp. 3905-3913 ◽  
Author(s):  
Eric A. Shaede ◽  
Leon M. Dorfman ◽  
Garry J. Flynn ◽  
David C. Walker
Keyword(s):  
Pulse Radiolysis ◽  
Chemical Yield ◽  
Molar Absorptivity ◽  
Solvated Electrons ◽  
Experimental Conditions ◽  
Hexamethylphosphoric Triamide ◽  
Radiation Chemical ◽  
Optical Absorption Band ◽  
Bromide Ion ◽  
Kinetics Of

The spectrum, yield, and kinetics of solvated electrons in hexamethylphosphoric triamide were investigated by the pulse radiolysis method. The optical absorption band is in the infrared with a maximum at 2200 ± 100 nm. The molar absorptivity at this maximum is (3.2 ± 0.5) × 104 M−1 cm−1, and the oscillator strength for the transition is estimated to be f = 0.7 ± 0.2. A free ion yield of G(es−) = 2.3 + 0.4 solvated electrons/100 eV was determined from the observed yields of anthracene and pyrene radical anions formed by electron attachment.Kinetic studies provided values of the rate constants for the reaction of solvated electrons with anthracene and N2O. The decay mechanism of the solvated electrons in the absence of added solutes was found to be complex, and the half-life (in the range of 2 to 50 μs) was dependent on experimental conditions. A second transient species, absorbing at wavelengths below 500 nm, was observed but not identified. In solutions containing bromide ion the species Br2− was observed. The pulse radiolysis of stable solutions of es−, formed by dissolving sodium metal in HMPA, is also reported.

Kinetics of solvated electrons in reaction with hexamethylphosphoric triamide

1995 ◽  
Vol 91 (21) ◽  
pp. 3809-3812 ◽  
Author(s):  
Céline G. Jung ◽  
Fabienne Peeters ◽  
José Castillo ◽  
Stéphane Boué ◽  
André Fontana
Keyword(s):  
Solvated Electrons ◽  
Hexamethylphosphoric Triamide ◽  
Kinetics Of

Radiation chemical yield of OH- as determined by conductometric pulse radiolysis

1971 ◽  
Vol 75 (11) ◽  
pp. 1759-1760 ◽  
Author(s):  
A. Henglein ◽  
J. Rabani ◽  
M. Graetzel ◽  
S. A. Chaudhri ◽  
G. Beck
Keyword(s):  
Pulse Radiolysis ◽  
Chemical Yield ◽  
Radiation Chemical Yield ◽  
Radiation Chemical

Pulse Radiolysis of Tetraphenylcyclobutane in Hexamethylphosphoric Triamide Solution

1978 ◽  
Vol 33 (11) ◽  
pp. 1281-1284 ◽  
Author(s):  
S. Takamuku ◽  
B. Dinh-Ngoc ◽  
W. Schnabel
Keyword(s):  
Optical Absorption ◽  
Pulse Radiolysis ◽  
Electron Attachment ◽  
Radical Anions ◽  
Dissociative Electron Attachment ◽  
Dilute Solutions ◽  
Solvated Electrons ◽  
Hexamethylphosphoric Triamide ◽  
Attachment Process

r-1, c-2, t-3, t-4-tetraphenvlcyclobutane (TPCB) was irradiated in dilute solutions of hexamethylphosphoric triamide (HMPT) with 20 ns pulses of 16 MeV electrons. Solvated electrons (e-solv) produced during the radiolysis of HMPT react with TPCB with k = (6 ± 1) · 109 l/mol s. Simultaneously with the decay of the optical absorption of the solvated electrons, the formation of the absorption of t-stilbene (at 300 nm) and that of stilbene radical anions (at 500 nm) was observed. Thus, it is concluded th at TPCB is undergoing a dissociative electron attachment process e-solv + TPCB→t-St + t-St·̄̅. The lifetime of a possible intermediate (TPCB·̄̅) was estimated as being smaller than 10-9 s. The 100 eV yield of t-stilbene was determined as G(t-St) = 3.4.

scholarly journals Kinetics of Non-Enzymatic Synthesis of Dipeptide Cbz-Phe-Leu with AOT Reversed Micelles

Processes ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 1003
Author(s):  
Michiaki Matsumoto ◽  
Tadashi Hano
Keyword(s):  
Enzymatic Synthesis ◽  
Maximum Yield ◽  
Side Reactions ◽  
Experimental Conditions ◽  
Operational Conditions ◽  
Ph Dependency ◽  
Optimum Water Content ◽  
Short Time ◽  
Kinetics Of ◽  
Aot Reversed Micelles

The non-enzymatic synthesis of N-benzyloxycarbonyl-L-phenylalanyl-L-leucine (Cbz-Phe-Leu) from lipophilic N-benzyloxycarbonyl-L-phenylalanine (Cbz-Phe) and hydrophilic L-leucine (Leu), by N, N’-dicyclohexylcarbodiimide (DCC) as a condensing agent, was carried out using a reversed micellar system composed of bis(2-ethylhexyl) sodium sulfosuccinate (AOT) as a surfactant and isooctane. We successfully synthesized Cbz-Phe-Leu in a short time and investigated the effects of its operational conditions, the DCC concentration, w0, and the pH on the kinetic parameters and the maximum yields. For dipeptide synthesis, we had to add an excess of DCC with the substrates because of the side reactions of Cbz-Phe. From the pH dependency of the reactivity, a partially cationic form of Leu was better for a synthesis reaction because of the enrichment of Leu at the interface by anionic AOT. The optimum water content on the dipeptide synthesis was w0 = 28 due to the competition of the peptide synthesis and the side reactions. The maximum yield of Cbz-Phe-Leu was 0.565 at 80 h under optimum experimental conditions.

Copolymerization of Isobutene and Isoprene at “High” Temperature with Syncatalyst Systems Based on Aluminum Organic Compounds

1976 ◽  
Vol 49 (4) ◽  
pp. 937-959 ◽  
Author(s):  
S. Cesca ◽  
M. Bruzzone ◽  
A. Priola ◽  
G. Ferraris ◽  
P. Giusti
Keyword(s):  
Energy Savings ◽  
Ion Pairs ◽  
Great Part ◽  
Methyl Chloride ◽  
Reactivity Ratio ◽  
Experimental Conditions ◽  
Noticeable Increase ◽  
Catalyst Systems ◽  
Kinetics Of ◽  
Kinetics Of Vulcanization

Abstract New catalyst systems based on alkylaluminum derivatives and halogen or interhalogen compounds were found highly efficient in the synthesis of high-molecular-weight IIR at temperatures above − 50°C. The reaction mechanism was studied in detail for the system Et2AlCl + Cl2. The reactions occurring between chlorine, isobutene, Et2AlCl, and the solvent (CH3Cl) were elucidated and studied under various experimental conditions (e.g. presence or absence of light, simultaneous presence of the copolymerization system components, temperature, type of halogen, use of model compound of isobutene). It was concluded that halogenium ions, i.e. Cl+, Br+, or I+, are the initiating species. Kinetic and conductometric investigations showed that scarcely dissociated ion pairs, e.g. Cl+[Et2AlCl2]−, were formed in the absence of monomer; but in the presence of isobutene, a noticeable increase of the electrical conductivity and rapid polymerization occurred. The maximum polymerization rate was first order with respect to the concentrations of monomer, Cl2, and Et2AlCl. In the homopolymerization of isobutene, transfer to monomer and termination reactions were negligible. The MW of IIR was found to be mainly dependent on the concentrations of the catalyst components, on isoprene concentration, and on temperature. The reactivity ratio of isobutene with isoprene was found to be r1=2.5±0.5 at −35°C, while the activation energies relative to MW were −5.8 ± 0.4, kcal/mol for polyisobutene, and −5.7 ± 0.7 and − 4.3 ± 0.5 kcal/mol for IIR containing, respectively, 1.3 and 1.9 mol% of isoprene. The evaluation of some physicochemical and technological properties of typical IIR produced with the system Et2AlCl + Cl2, indicated that isoprene is randomly distributed along the chains and that the MWD is monomodal, while the glass transition temperature, tensile properties, mechanical-dynamic spectra, and kinetics of vulcanization are very similar to those of commercial IIR. Very preliminary data, referring to several classes of new catalyst systems yielding IIR having good properties, were also obtained. The syncatalyst systems here described can work in a homogeneous phase consisting of an aliphatic hydrocarbon besides methyl chloride, still giving IIR with high MW. Therefore, a completely homogeneous process can be envisioned for the synthesis of IIR at −50°C thus avoiding a great part of the fouling problems of the slurry process. The economic advantage of using “high” temperatures of polymerization is briefly discussed in terms of energy savings.

Thermal Breakdown Kinetics of 1-Ethyl-3-Methylimidazolium Ethylsulfate Measured Using Quantitative Infrared Spectroscopy

2017 ◽  
Vol 71 (12) ◽  
pp. 2626-2631 ◽  
Author(s):  
Jeffrey L. Wheeler ◽  
McKinley Pugh ◽  
S. Jake Atkins ◽  
Jason M. Porter
Keyword(s):  
Thermal Stability ◽  
Room Temperature ◽  
Computational Models ◽  
Elevated Temperatures ◽  
Molar Absorptivity ◽  
Ir Absorption ◽  
Optical Cell ◽  
Multiple Samples ◽  
Kinetics Of ◽  
Thermal Stability Of

In this work, the thermal stability of the room temperature ionic liquid (RTIL) 1-ethyl-3-methylimidazolium ethylsulfate ([EMIM][EtSO4]) is investigated using infrared (IR) spectroscopy. Quantitative IR absorption spectral data are measured for heated [EMIM][EtSO4]. Spectra have been collected between 25 ℃ and 100 ℃ using a heated optical cell. Multiple samples and cell pathlengths are used to determine quantitative values for the molar absorptivity of [EMIM][EtSO4]. These results are compared to previous computational models of the ion pair. These quantitative spectra are used to measure the rate of thermal decomposition of [EMIM][EtSO4] at elevated temperatures. The spectroscopic measurements of the rate of decomposition show that thermogravimetric methods overestimate the thermal stability of [EMIM][EtSO4].

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