Browsing by Subject "Acetonitrile"

Now showing 1 - 3 of 3

Open Access
Electroinitiated polymerization of 2-chloroethylvinyl ether
(1998) Kalaycioglu, E.; Toppare L.; Yagci, Y.
The electroinitiated polymerization of 2-chloroethylvinyl ether via controlled potential conditions has been achieved. The kinetics of the polymerization were determined by cyclic voltammetry at different temperatures in dichloromethane (DM) and acetonitrile (AN). The post-polymerization kinetics were followed with a similar technique. It was found that polymerization was twice as fast in DM as in AN. In DM, both the polymerization and the post-polymerization rates increased with decreasing temperature, whereas in AN the reverse behavior was observed.
Open Access
Highly sensitive determination of 2, 4, 6-trinitrotoluene and related byproducts using a diol functionalized column for high performance liquid chromatography
(Public Library of Science, 2014) Gumuscu, B.; Erdogan, Z.; Güler, Mustafa O.; Tekinay, T.
In this work, a new detection method for complete separation of 2,4,6-trinitrotoluene (TNT); 2,4-dinitrotoluene (2,4-DNT); 2,6-dinitrotoluene (2,6-DNT); 2-aminodinitrotoluene (2-ADNT) and 4-aminodinitrotoluene (4-ADNT) molecules in high-performance liquid-chromatography (HPLC) with UV sensor has been developed using diol column. This approach improves on cost, time, and sensitivity over the existing methods, providing a simple and effective alternative. Total analysis time was less than 13 minutes including column re-equilibration between runs, in which water and acetonitrile were used as gradient elution solvents. Under optimized conditions, the minimum resolution between 2,4-DNT and 2,6-DNT peaks was 2.06. The recovery rates for spiked environmental samples were between 95-98%. The detection limits for diol column ranged from 0.78 to 1.17 μg/L for TNT and its byproducts. While the solvent consumption was 26.4 mL/min for two-phase EPA and 30 mL/min for EPA 8330 methods, it was only 8.8 mL/min for diol column. The resolution was improved up to 49% respect to two-phase EPA and EPA 8330 methods. When compared to C-18 and phenyl-3 columns, solvent usage was reduced up to 64% using diol column and resolution was enhanced approximately two-fold. The sensitivity of diol column was afforded by the hydroxyl groups on polyol layer, joining the formation of charge-transfer complexes with nitroaromatic compounds according to acceptor-donor interactions. Having compliance with current requirements, the proposed method demonstrates sensitive and robust separation. © 2014 Gumuscu et al.
Open Access
Spectroelectrochemistry of potassium ethylxanthate, bis(ethylxanthato)nickel(II) and tetraethylammonium tris(ethylxanthato)-nickelate(II)
(Royal Society of Chemistry, 2001) Dag, Ö.; Yaman, S. Ö.; Önal, A. M.; Isci, H.
Electrochemical and chemical oxidation of S2COEt−, Ni(S2COEt)2, and [Ni(S2COEt)3]− have been studied by CVand in situ UV-VIS spectroscopy in acetonitrile. Cyclic voltammograms of S2COEt− and Ni(S2COEt)2 display one (0.00 V) and two (0.35 and 0.80 V) irreversible oxidation peaks, respectively, referenced to an Ag/Ag+ (0.10 M) electrode. However, the cyclic voltammogram of [Ni(S2COEt)3]− displays one reversible (−0.15 V) and two irreversible (0.35, 0.80 V) oxidation peaks, referenced to an Ag/Ag+ electrode. The low temperature EPR spectrum of the oxidatively electrolyzed solution of (NEt4)[Ni(S2COEt)3] indicates the presence of [NiIII(S2COEt)3], which disproportionates to Ni(S2COEt)2, and the dimer of the oxidized ethylxanthate ligand, (S2COEt)2 ((S2COEt)2 = C2H5OC(S)SS(S)COC2H5), with a second order rate law. The final products of constant potential electrolysis at the first oxidation peak potentials of S2COEt−, Ni(S2COEt)2, and [Ni(S2COEt)3]− are (S2COEt)2; Ni2+(sol) and (S2COEt)2; and Ni(S2COEt)2 and (S2COEt)2, respectively. The chemical oxidation of S2COEt− to (S2COEt)2, and [Ni(S2COEt)3]− to (S2COEt)2 and Ni(S2COEt)2 were also achieved with iodine. The oxidized ligand in the dimer form can be reduced to S2COEt− with CN− in solution.