Microcrystalline powder

Sodium Peroxoborate. Sodium peroxoborate [10332-33-9] (sodium perborate monohydrate), Na2[82(02)2(011)4], formerly written as NaBO H20, is known only as a microcrystalline powder, made by dehydrating the hexahydrate. The crystal stmcture has not been deterrnined, but the vibrational spectmm (27) indicates the presence of the same cycHc peroxodiborate anion (4) as that in the hexahydrate as well as in the tetrahydrate. 

The latter is a microcrystalline powder, m.p. 265° (efferv.), [a] + 210° (N/10 HCl), gives a Millon reaction and like all the phenolic alkaloids of this group is readily oxidised by nitric acid. 

Lettocine, Cj7H2502N, is a pale brown microcrystalline powder, m.p. 350-2° it yields a crystalline hydriodide, B. HI, m.p. 256° dec.) picrate, m.p. 198°, and is recovered unchanged from boiling acetic anhydride. Bertho suggested that it may be a condensed form of a Kurchi alkaloid (p. 742). 

To anhyd CuCl2 (30 mg, 0.223 mol) dissolved in anhyd DMF (2 mL) was added dioxouranium(VI) super-phthalocyanine (0.10 g, 0.11 mol), and the mixture was heated under N2 for 3 h at 120 C with stirring. After this time, the solvent was removed in vacuo and the resulting solid was washed with H20, acetone, and Et,0, and then vacuum dried to give a violet, microcrystalline powder yield 60 mg (95%). 

Method A Tetrabutylammonium perchlorate (8.5 g, 25 mmol) was added to a solution containing DMF (49.5 mL) and hydrazine hydrate (0.5 tnL). To this solution was added green Pc2Lu (50 mg, 4.1 x 10 2 mmol). This mixture was stirred for 4 h. The blue-green of the starting solution rapidly became dark blue. Filtration and rapid evaporation under vacuum yielded 7 as a microcrystalline powder. 

Fine, pale yellow, amorphous, or microcrystalline powder. May come as sublimed, washed, or precipitated. Pure sulfur exists in two stable crystalline forms and at least two amorphous... 

A second example is the synthesis of the TTF[M(dmit)2]j compounds, where M = Ni, Pd or Pt. Metathesis reaction under inert atmosphere of CH3CN solutions of (TTF)3(BP4)2 and the appropriate metal salt TBA[M(dmit)2] immediately yields insoluble, black, shiny microcrystalline powders. Because TTF[M(dmit)2]j is virtually insoluble in common solvents, its recrystallization from solution is precluded. Therefore, when single crystals are needed some alternative synthesis routes have to be undertaken. 

For many molecular materials, crystallization from solution does not yield single crystals of suitable size and quality for single-crystal XRD, and instead produces only microcrystalline powders. In such cases, structure determination from powder XRD data provides a viable route for establishing structural understanding of the resultant materials. 

Certain solid phases, on the other hand, cannot be obtained (even as microcrystalline powders) by crystallization experiments, but instead can be generated only by other types of preparation procedure. Some types of preparation processes commonly (or in some cases inherently) yield microcrystaUine products, including (1) preparation of materials directly from solid-state chemical reactions (see Sect. 6.6), (2) preparation of materials by solid-state desolvation processes (see Sect. 6.4), (3) preparation of materials by solid-state grinding (mechanochemical) processes (see Sect. 6.2), and (4) preparation of materials directly by rapid precipitation from solution (as opposed to crystallization) (see Sect. 6.7). Again, structure determination from powder XRD data may represent the only opportunity for determining the structural properties of new solid phases obtained by such processes. 

Many crystalline solids can undergo chemical transformations induced, for example, by incident radiation or by heat. An important aspect of such solid-state reactions is to understand the structural properties of the product phase obtained directly from the reaction, and in particular to rationalize the relationships between the structural properties of the product and reactant phases. In many cases, however, the product phase is amorphous, but for cases in which the product phase is crystalline, it is usually obtained as a microcrystalline powder that does not contain single crystals of suitable size and quality to allow structure determination by single-crystal XRD. In such cases, there is a clear opportunity to apply structure determination from powder XRD data in order to characterize the structural properties of product phases. 

The product is a red-brown microcrystalline powder that appears to be stable toward air and moisture but should be stored under N2- The compound is soluble in polar organic solvents such as diethyl ether, tetrahydrofuran, dichloromethane. 

A solution of 3,5-di-tert-butyl-2-hydroxybenzaldehyde (1.0 mmol) in toluene (8 mL) was added to a solution of benzyl-4,6-0-isopropylidene-2-amino-2-deoxy-a-D-glucoside (1.0 mmol) in the same solvent (8mL). The resulting mixture was stirred for 2 h at 80 °C affording a yellow solution. The volume of the solvent was reduced under vacuum to ca. 3 mL and hexane (8 mL) was slowly added to afford the product as a yellow microcrystalline powder, which was washed with hexane (2x8 mL) and dried under vacuum (0.45 g, 85 % yield). 

The complex [Pt(terpy)Me]Cl is obtained as an orange to yellow, microcrystalline powder depending on the crystal packing. It is soluble in... 

Dichloro[cate a-2-methyl-l,4-butadiene]dicopper(I) (B) can be prepared from direct reaction between isoprene and copper(I) chloride, analogously to the synthesis of the complex between butadiene and CuCl.12 The advantage of the synthesis described here is that the product is not contaminated with unreacted CuCl, and can be obtained as high-quality crystals instead of a microcrystalline powder. 

In an excess of concentrated (30 per cent) hydrogen peroxide to which a little sulfuric acid has been added to insure acidity, dissolve the potassium metavanadate, observing that the color changes to an intense yellow. To this solution, well cooled, add 95 per cent alcohol until the pervanadate has been precipitated as a microcrystalline powder. Filter off the product, wash with alcohol, and dry in a desiccator over calcium chloride. 

The product is a microcrystalline powder which can be hydrolysed to hydroxylamine by heating in acid solution. 

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