Brown powder

Cobali in) fluoride, C0F3. Brown powder (C0F3 plus F2) also forms a green hydrate by electrolytic oxidation. C0F3 is widely used in the fluorinalion of organic derivatives. Gives complexes e.g. MjCoFg. 

Silicon monoxide, SiO. Formed Si02 plus C in electric furnace. The impure brown powder is used as a pigment and abrasive (Monex). Stable in vapour phase (Si plus Si02). 

Silicon is prepared commercially by heating silica and carbon in an electric furnace, using carbon electrodes. Several other methods can be used for preparing the element. Amorphous silicon can be prepared as a brown powder, which can be easily melted or vaporized. The Gzochralski process is commonly used to produce single crystals of silicon used for solid-state or semiconductor devices. Hyperpure silicon can be prepared by the thermal decomposition of ultra-pure trichlorosilane in a hydrogen atmosphere, and by a vacuum float zone process. 

Tungsten dioxide [12036-22-5] WO2, is a brown powder formed by the reduction of WO3 with hydrogen at 575—600°C. Generally, this oxide is obtained as an intermediate in the hydrogen reduction of the trioxide to the metal. On reduction, first a blue oxide, then a brown oxide (WO2), is formed. The composition of the blue oxide was in doubt for a long time. However, it has since been resolved that W2Q03g and W are formed as intermediates, which may also be prepared by the reaction of tungsten with WO3. 

Tungsten trisulfide [12125-19-8] chocolate-brown powder, slightly soluble in cold water, but readily forming a colloidal solution in hot... 

Diethyl phthalimidomalonate [56680-61-5] M 305.3, m 72-74 , 73-74 , pK 9.17. Dissolve in xylene and when the temperature is 30° add pet ether (b 40-60°) and cool to 20° whereby the malonate separates as a pale brown powder [Booth et al. J Chem Soc 666 1944], Alternatively, dissolve in C6H6, dry over CaCl2, filter, evaporate and the residual oil solidifies. This is ground with Et20, filter and wash with Et20 until white in colour, and dry in a vacuum. The anion has Xmax 254nm (e 18.5K) [Clark and Murray Org Synth Coll Vol I 271 1941 UV of Na salt Nnadi and Wang J Am Chem Soc 92 4421 1970],... 

Bipyridinium chlorochromate [76899-34-8] M 292.6. Washed with cold cone HCl then H2O (sintered glass funnel) and dried in vacuum (CaCl2) to a free flowing yellow-brown powder. Stored in the dark. [Synthesis 691 1980 Synth Commun 10 951 1980.] SUSPECTED CARCINOGEN. 

Copper (I) thiophenolate [1192-40-1] M 172.7, m ca 280°, pKj 6.62 (for PhS ). The Cu salt can be extracted from a thimble (Soxhlet) with boiling MeOH. It is a green-brown powder which gives a yellow-green soln in pyridine. Wash with EtOH and dry in a vacuum. It can be ppted from a pyridine soln by addition of H2O, collect ppte, wash with EtOH and dry in a vacuum. [Synthesis 662 1974, J Am Chem Soc 79 170 1957-, Chem Ber 90 425 1957.]... 

Palladium (II) trifluoroacetate [42I96-3I-6] M 332.4, m 210"(dec). Suspend in trifluoroacetic acid and evaporate on a steam bath a couple of times. The residue is then dried in vacuum (40-80°) to a brown powder. [J Chem Soc 3632 7965 J Am Chem Soc 102 3572 1980.]... 

The undistilled aqueous tartaric acid solution was extracted with three 1-liter portions of ethyiene dichloride, and was then brought to a pH of about 8.5 to 9.5 by the addition of 28% aqueous ammonium hydroxide. The ammoniacal solution was extracted with three 1-liter portions of ethylene dichloride the ethylene dichloride extracts were combined, were dried, and were evaporated in vacuo, yielding a residue of 3.35 grams of a iight-brown powder. 

A mixture of 2,3-dibromo-l,4-diheptylnaphthalene (3.6 g, 7.5 mmol) and CuCN (4 g, 44 mmol) in DMF (20 mL) was heated under reflux for 6 h. Coned NH, (80 mL) was added and air was bubbled through the suspension for 10 h. The precipitate was filtered and extracted with CHC13. The solvent was evaporated and the residue recrystallized (hexane) to obtain a pale-brown powder yield 800 mg (36%) mp 101-103 C. 

Under N2, clean Li metal (0.17 g, 25 mmol) was placed in a round-bottom flask with a solvent mixture of MeOH (3 mL) and pcntan-t-ol (17 mL). The mixture was heated under N, until the reaction with Li was complete. Then, naphthalene-2,3-dicarbonitrilc (2 g, 11 mmol) was added to the mixture which turned green-brown the mixture was refluxed for 3h. The brown powder, obtained after cooling and removal of the solvent under reduced pressure, was dissolved in anhyd acetone (20 mL) and then hexane (70 mL) was added. The green precipitate was separated from the brown solution by filtration. This purification by precipitation was repeated twice. The green precipitate was placed in a Soxhlet extractor and extracted for 3 h with acetone (200 mL) in order to separate the product from the insoluble metal-free species and LiOH. The acetone solution was evaporated down to a volume of 20 mL. The product precipitated after the addition of hexane (70 mL). This latter purification step was performed several times yield 1.29 g (64%). 

A mixture of l,4-di(hexyloxy)naphthalene-2,3-dicarbonitrile (756 mg, 2 mmol), Ni(OAc)2 (175 mg, 0.7 mmol), and DBU (1.5 mL) in hexan-l-ol (25 mL) was heated under N2 for 24 h under reflux. The cooled green-brown solution was poured into MeOH/H20 (1 1,150 mL) and the precipitate formed was filtered, washed with MeOH, and dried in vacuo. Further purification was achieved by column chromatography (silica gel, CHC13) in the dark to yield the title compound as a light-brown powder yield 480 mg (61 %). 

RuF3 can be made by iodine reduction of RuF5. It is obtained as a dark brown powder that contains corner-shared RuF6 octahedra [15], RuC13 exists in a- and /3-phases ... 

Freund (Ref 2) nitrated a fraction of Galician petroleum (from Borislaw), bp 270—380°, d 0.858—0.870g/cc (previously purified by treatment with 1% coned sulfuric acid), and obtained a red-brown powder with a N content of about 6.8%... 

Cerium Picrate. [C6H2(N02)30]3Ce, mw 824.45, N 15.29%, brown powder which explds violently at 306—13°. Can be prepd by heating either its trlhydrate or undecahydrate Refs 1) Beil 6,277 2) O. Silberrad H.A. 

For the synthesis of 3a, 1.1 equivalent of the ligand 2a (0.25 g 0.31 mmol) and (DME)NiBr2 (0.068 g 0.28 mmol) were stirred in 20 ml of CH2CI2 for ovemi t. After removing of the solvent, the brown powder was washed three times with diethyl ether (yield =... 

Amaranth (E 123, Cl Food Red 9) is a mono azo dye, with the chemical name trisodium 3-hydroxy-4(4-sulfonato-l-naphtylazo)-2,7-naphthalenedisulfonate) (or trisodium 2-hydroxy-l-(4-sulfonato-l-napthylazo) naphthalene-3,6-disulfonate). The calcium and potassium salts are also permitted. Amaranth is a reddish-brown powder or granules, soluble in water, sparingly soluble in ethanol, with a maximum absorption in water at 520 nm (Ei " = 440). It has been banned in the US since 1976. " Amaranth can be used also as a dye for cosmetics, synthetic fibers, leather, papers, and some plastics. 

Fast Red E (Red No. 4, Cl Food Red 4) is a mono azo dye consisting mainly of disodinm 2-hydroxy-l-(4-snlfonato-l-naphthylazo) naphthalene-6-snlfonate. It is a red-brown powder or grannies, solnble in water, sparingly solnble in ethanol. It is not permitted for use in the US and EU. "... 

Jons Jakob Berzelius (1779-1848) treated potassium fluorosilicate with potassium to obtain amorphous silicon as a brown powder. 

III [H(H20)2]2 Tc8(/ -Br)8Br4]Br2 Black oblong (up to 5 mm) needle-like crystals with a square cross-section. No metallic lustre is observed. Very soluble in HBr (concentr.), alcohol and other polar solvents, forming reddish-brown solutions. Grinding yields reddish-brown powder. 

V [(C2H 5)4N] 2 [Tc6(/t-Br)6]Br6]Br2 Black-brown dendrite-like crystals consisting of fine needles. Soluble in hot HBr (concentr.), slightly soluble in polar organic solvents forming brown solutions. Grinding yields black-brown powder. 

VI [(CH 3)4N] 3 [Tc6( -Br)6Br6]Br 2 Black-brown plate- and needle-like crystals. Soluble in hot HBr (concentr.), forming black-brown solutions. Grinding yields brown powder with a violet tinge... 

---