Solvents, aprotic spectrometry

It was in 1990 that Kratschmer et al. [217,218] reported the first macroscopic preparation of in gram quantities by contact-arc vaporization of a graphite rod in a 100 Torr atmosphere of helium, followed by extraction of the resultant soot with toluene. Fullerene ions could also be detected by mass spectrometry in low-pressure hydrocarbon flames [219]. The door was opened by, Kratschmer and co-workers preparative success to extensive studies of the electrochemical behavior of the new materials. Cyclic voltammetry of molecular solutions of Ceo in aprotic electrolytes, e.g., methylene chloride/quatemary ammonium salts, revealed the reversible cathodic formation of anionic species, the radical anion, the dianion, etc. (cf. [220,221]). Finally, an uptake of six electrons in the potential range of 1-3.3 V vs. SHE in MeCN/toluene at — 10°C to form the hexavalent anion was reported by Xie et al. [222]. This was in full accordance with MO calculations. A parametric study of the electroreduction of Cgo in aprotic solvents was performed [223]. No reversible oxidation of C o was possible, not even to the radical cation. However, the stability of di- and trications with special counterions, in the Li/PEO/C 3 MoFf cell, was claimed later [224]. 

This book is based on the study of reactions of thermal electrons with molecules using the ECD, negative ion chemical ionization (NICI) mass spectrometry in the gas phase and polarographic reduction in aprotic solvents [18]. Only the complementary studies related to our research are considered here. 

This book is based on the reactions of thermal electrons with molecules. The ECD, negative-ion chemical ionization (NICI) mass spectrometry, and polaro-graphic reduction in aprotic solvents methods are used to determine the kinetic and thermodynamic parameters of these reactions. The chromatograph gives a small pure sample of the molecule. The temperature dependence of the response of the ECD and NIMS is measured to determine fundamental properties. The ECD measurements are verified and extended by correlations with half-wave reduction potentials in aprotic solvents, absorption spectra of aromatic hydrocarbons and donor acceptor complexes, electronegativities, and simple molecular orbital theory. 

Potassium superoxide in aprotic solvents Stopped flow spectrometry Alkaline solution... 

Saf, R., Mirtl C., and Hummel, K. Electrospray mass-spectrometry using potassium-iodide in aprotic organic solvents for the ion formation by cation attachment. Tetrahedron Lett., 35, 6653, 1994. 

Hydrophilic interaction chromatography (HILIC) is a separation process involving polar stationary phases with mobile phases made of highly polar aprotic organic solvents (>80 %) and a small amount of aqueous solvents. It is particularly suitable for the separation of very polar analytes. HILIC coupled to mass spectrometry may offer a significant increase in sensitivity. The isocratic separation of three calystegines (A5, B4, and Cl) on an Acquity HILIC (50 x 2.1 mm, 1.7 pm) column with MeOH-10 mM aqueous ammonium acetate buffer at pH 5 (95 5) and a flow rate of 400 pL min was possible in less than 1.5 min [29]. 

Saf, R. Miitl, C. Hummel, K. Electrospray Mass Spectrometry Using Potassium Iodide in Aprotic Organic Solvents for the Ion Formation by Cation Attachment. Tetrahedron Lett. 1994, 35, 6653-6656. 

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