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The molecular geometries, normal mode frequencies, intensities and corresponding infrared assignments of monomeric and dimeric
2,3-dimethylpyridine, 2,4-dimethylpyridine, 3,4-dimethylpyridine, 3,5-dimethylpyridine and monomeric 2,6-dimethylpyridine
in the ground state were investigated at the density functional theory (DFT)-B3LYP level using the 6-311+G(d, p) basis set.
The vibrational frequencies and geometric parameters of C–H stretching and bending in the fundamental region were calculated
and compared to the Fourier transform infrared (FT-IR) data obtained. In the studied monomeric and dimeric dimethyl substituted
pyridine derivatives, the C–H stretching and bending frequency shifts that occur between the dimer and the monomer may be
diagnostic of the magnitude of dimerization energy. As supported by data in the literature, the most stable dimeric form was
obtained for the 3,4-dimethylpyridine molecule.
Figure Molecular model and numbering scheme of the studied dimeric dimethylpyridinederivatives 相似文献
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E. M. Harper Goksin Kavlak Lara Burmeister Matthew J. Eckelman Serkan Erbis Vicente Sebastian Espinoza Philip Nuss T. E. Graedel 《Journal of Industrial Ecology》2015,19(4):628-644
Concerns about the future availability and continuity of metal supplies have triggered research efforts to define and assess metal criticality. In this study, we apply a comprehensive methodology to the elements of the geological zinc, tin, and lead family: zinc (Zn); germanium (Ge); cadmium (Cd); indium (In); tin (Sn); and lead (Pb). Zn, Sn, and Pb have played important roles in various technological sectors for centuries, whereas Ge, Cd, and In are by‐product metals that are increasingly utilized in emerging and strategic technologies. Criticality assessments are made on national (i.e., the United States) and global levels for 2008. The results are presented with uncertainty estimates in three‐dimensional “criticality space,” comprised of supply risk (SR), environmental implications, and vulnerability to supply restriction (VSR) axes. SR is the highest for In for both the medium (i.e., five to ten years) and long term (i.e., a few decades). Pb and Zn have the lowest SR for the medium term and Pb the lowest SR for the long term. In and Ge production have the highest environmental burdens, mainly as a result of emissions from Zn smelting and subsequent metals purification and recovery from Zn leaching residues. VSR is highest for Pb at the global and national levels. 相似文献
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