Crystal color

Other Transition Element Perchlorates. Both divalent and trivalent manganese perchlorate compounds [13770-16-6 13498-03-8] are known. Perchlorates of Fe, Co, Ni, Rh, and Pd have been produced as colored crystals (70—72). 

Mineral CAS Composition Coppe Color Crystal Luster Mohs Specific... 

With substances that give up an electron more readily than aromatic hydrocarbons, such as potassium, nickel carbonyl, cyanide ion, or iodide ion, complete transfer of an electron occurs and the TCNE anion radical is formed (11). Potassium iodide is a particulady usefiil reagent for this purpose, and merely dissolving potassium iodide in an acetonitrile solution of TCNE causes the potassium salt of the anion radical to precipitate as bronze-colored crystals. 

On cooling (to about io°) 15 g. of nitroanthrone separates out in long yellowish-white needles. After the addition of 100 cc. of water to the mother liquor 6 g. more, somewhat darker in color, crystallizes in three to four hours. 

To obtain a crystalline product, a solution of the residue in 30 ml. of benzene containing a few drops of triethylamine (Note 4) is placed in a 250-ml. Erlenmeyer flask, heated gently on a steam bath, and diluted with 150 ml. of hexane. Heating is continued for about 5 minutes (Note 5), after which the solution is allowed to cool to room temperature, seeded, and put in a freezer at —15° for at least 5 hours. The resulting solid is collected by suction filtration and washed with cold hexane. After vacuum drying, 5.8 g. (94%) of light cream-colored crystals, m.p. 75-77°, is obtained. 

From CS2 solution S7O2 is obtained as intensely orange colored crystals which on heating spontaneously decompose at 60-62 °C with evolution of sulfur dioxide. S7O2 is far less soluble in CS2 (ca. 1 g at 0 °C) than S7O. The solution decomposes within 1 h to a mixture of sulfur homocycles and SO2. Solid S7O2 decomposes at 25 °C within minutes and quantitatively within 2 h, even in the dark. Heating in a high vacuum to 50-60 °C produces S2O and elemental sulfur. The El mass spectrum therefore exhibits peaks due to these decomposition products only [67]. 

Oxidation of cyclo-Sio, dissolved in carbon disulfide, by trifloroperoxoacetic acid, dissolved in dichloromethane, at -30 °C (molar ratio 1 3) provides SioO in 14% yield, isolated as orange-colored crystals (after recrystallization from CH2CI2) [83] ... 

A mixture of 2-indolinone 187 (6.66 g, 50 mmol), pyrrohdine (12.52 mL, 150 mmol), and HMDS 2 (15.5 mL, 75 mmol) is heated under reflux for 3 h with TSOH H2O (0.475 g, 2.5 mmol) under argon in an oil-bath at 125-130°C. After 1 h 188 starts to crystallize. After cooling to 24 °C the crystals of 2-pyrrohdino-3H-indole 188 are isolated by filtration and washed with acetone to give 7.07 g (76%) sand-colored crystals, m.p. 140-142 °C, which can be readily recrystalhzed from boiling acetone under argon [27] (Scheme 4.56). 

The sodium metal reduction of [(Me3C6H2)C6H3]GaCl215 (Eq. 7) afforded a dark red, almost black, solution from which was obtained similarly colored crystals. This substance was unlike any other that had been prepared in that it existed as... 

To the best of the author s knowledge, the only isolated diaza analog of o-benzoquinone is bis-N-oxide 79 and its derivatives. Compound 79 was isolated as orange-colored crystals from a reaction of tetraketo derivative 78 with dinitrogen tetroxide (76TL1703 77AP264). 

The tri(azulenyl)methane derivative 24+ including a 6-azulenyl group was prepared by the reaction of azulene 6b with diethyl 6-formylazulene-l,3-dicarboxylate. Synthesis of 24+ was accomplished by hydride abstraction with DDQ. Cation 24+ was isolated as a hexafluorophosphate salt by treatment with aqueous HPF6. The new salt is a stable, deep-green colored crystals, that can be... 

The initial stages of the DBX-1 synthesis using Cun-purified NaNT in place of raw NaNT produced similar observations as described above. Upon addition of the initial dose of sodium ascorbate, a gel-like material was formed with no evidence of crystalline DBX-1. After an apparent induction period of several minutes, a very different phenomenon was noticed. These events included a visual change in reaction mixture turbidity (it became clear) and an almost instantaneous drop in the counts of fine particles (see Figure 1). As the fines dropped the PVM almost instantaneously identified crystalline DBX-1 (see Figure 2). The event only lasted seconds and produced the beautiful rust colored crystals indicative of DBX-1 product. The second dose of reducing agent was started (denoted by the second start on the x axis) after formation of the DBX-1 crystals was identified. 

Colorless to white to cream-colored crystals. May darken on exposure to air or light. 

Of some interest are the different colored crystals resulting from compounding rhodium with the halogens RhF = red, RhCl = red, RhBrj = brown, and Rel = black. 

If the levels D and CD in Fig. 29 lie far enough beneath the conduction band (i.e., vd and vcd are sufficiently large), as is the case, for example, with the alkali halide crystals, then the transitions 3 and 4 may be neglected (in the absence of any other ionizing agents besides the temperature), and adsorption processes on the neutral and on the ionized F centers will be independent of each other. In this case the adsorptivity (at small pressures) of a colored crystal (i.e., a crystal containing neutral F centers) will be... 

Compoimds of the elements are also presented in similar format. This includes CAS Registry Numbers, formulas, molecular weights and the hydrates they form (if any). This is followed by occurrence (for naturally occurring compounds) and industrial applications. The section on Physical Properties covers the color, crystal structure, density, melting and boiling points and solubihties of the compounds in water, acids, alkalies and organic solvents. 

SYNTHESIS To 500 mL concentrated nitric acid, stirred and cooled with an external ice-bath there was added, a bit at a time, 50 g of finely powdered piperonal. The temperature must not be allowed to rise above 0 °C during the addition. After two hours of additional stirring, the reaction was poured over chipped ice, the product removed by filtration and washed with H20 to remove all traces of acid. After recrystallization from a 50 / 50 mixture of ethyl acetate and ethanol, the product, 2-nitro-4,5-methylenedioxybenzaldehyde, was obtained as lemon-yellow colored crystals that weighed 47 g... 

A solution of 6.0 g indole-3-acetonitrile in 15 mL anhydrous THF was added dropwise to 160 mL of a 1 M solution of LAH in THF, stirred and held under reflux conditions. After an additional 8 h reflux, the reaction was cooled, and the excess hydride and reaction complex were decomposed by the careful addition of wet THF until the evolution of hydrogen ceased, then 25 mL 5% aqueous NaOH was added, followed by sufficient H20 to leave the inorganic solids with a filterable texture (about 15 mL additional). These solids were removed by filtration, the filter cake washed with THF, the filtrate and washings combined, and the solvent removed under vacuum. The solid residue was recrystallized from CH3CN to provide 5.3 g (86%) tryptamine as a cream colored crystal with a mp 112-114 °C. IR (in cm-1) 751, 811,882, 941, 1014, 1112 and 1128. 

Fluoropyridinium pyridine heptafluorodiborate (NFPy, 33) is prepared by reaction of fluorine with pyridine-boron trifluoride in acetonitrile or carbon tetrachloride at — 40-35 "C 69,70 its physical form is as stable, nonhygroscopic, lightly colored crystals. 

---