studied at the Hartree-Fock level with Gaussian basis sets including diffuse and polarization functions, as well as at the second-order Mprller-Plesset level. Vertical first detachment energies of several dianions were also calculated at the fourth-order Meller-Plesset level. All diatomic, triatomic, and tetratomic dianions were found to be unstabZe to electron loss. The pentatomic Mg2Si-dianion is predicted to be stable to electron loss with an electron detachment energy of 0.2 eV. This species is likely to be the smallest electronically stable linear dianion.
Future technologies are in need of solid-state materials showing the desired chemical and physical properties, and designing such materials requires a proper understanding of their electronic structures.
The qualifications of fractionating columns sufficiently small for general use by students include, besides satisfactory efficiency, also low hold-up and fairly high capacity. In a student column large hold-up may be a greater disadvantage than low efficiency, for some effects of the latter can be overcome by repeated fractionation, whereas a large hold-up retards the rate of improvement upon refractionation, reduces the amount of the high-boiling component recoverable, and, when the column is used for purification of preparations, decreases the yields.Because of the divergence of opinion as to the type of column best adapted to student use there was undertaken a comparative experimental study of the performance features of eight familiar types of small columns. Those examined were a plain tube, the Young pear-column, the simpler Clarke and Rahrs column, the Vigreux column, the plain kibe packed with pieces of glass rod or glass tubing, the Snyder column, and the Wurtz bulbed tube packed with rod. Working conditions were by intention approximately those of the student laboratory, and the outfits were simple enough for the use of students.The columns were compared under two sets of operating conditions: (1) without insulation or reflux control, and (2) with insulation and forced reflux. Results are discussed from the special viewpoint of the study. They permit ranking of the columns in the order (I) Snyder column, (2) packed plain tubes, (3) Vigreux column, (4) Clarke and Rahrs and Young columns, and (5) unpacked * To appear in the February issue,
Some Tolyl Derivatives of Germanium 3705 stirring into 200 cc. of water. The crude oxidation product which separated was filtered by suction within one half hour, and dried in a desiccator over concentrated sulfuric acid for about eighteen hours. The experimental data are given in Table I.
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