Copper bronze

Activated copper bronze. Commercial copper bronze does not always give satisfactory yields in the Ullmann reaction, but uniform results can... 

An interesting reaetion, which is particularly valuable for the preparation of diphenyl derivatives, consists in heating copper powder or, better, copper bronze with an aryl halide (Ullmann reaction), for example ... 

Place 50 g. of o-chloronitrobenzene and 75 g. of clean dry sand in a 250 ml. flask equipped with a mechanical stirrer. Heat the mixture in an oil or fusible metal bath to 215-225° and add, during 40 minutes, 50 g. of copper bronze or, better, of activated copper bronze (Section 11,50, 4) (1), Maintain the temperature at 215-225° for a further 90 minutes and stir continuously. Pour the hot mixture into a Pyrex beaker containing 125 g. of sand and stir until small lumps are formed if the reaction mixture is allowed to cool in the flask, it will set to a hard mass, which can only be removed by breaking the flask. Break up the small lumps by powdering in a mortar, and boil them for 10 minutes with two 400 ml. 

The experimental conditions for conducting the above reaction in the presence of dimethylformamide as a solvent are as follows. In a 250 ml. three-necked flask, equipped with a reflux condenser and a tantalum wire Hershberg-type stirrer, place 20 g. of o-chloronitrobenzene and 100 ml. of diinethylform-amide (dried over anhydrous calcium sulphate). Heat the solution to reflux and add 20 g. of activated copper bronze in one portion. Heat under reflux for 4 hours, add another 20 g. portion of copper powder, and continue refluxing for a second 4-hour period. Allow to cool, pour the reaction mixture into 2 litres of water, and filter with suction. Extract the solids with three 200 ml. portions of boiling ethanol alternatively, use 300 ml. of ethanol in a Soxhlet apparatus. Isolate the 2 2- dinitrodiphenyl from the alcoholic extracts as described above the 3ueld of product, m.p. 124-125°, is 11 - 5 g. 

Gattermann (1890) found that the preparation of the cuprous halide may be avoided by making use of the fact that finely-divided copper (e.g., freshly-precipitated or reduced by hydrogen or copper bronze) acts catal3d.ically in the decomposition of solutions of diazonium salts, for example ... 

In a 1 or 1-5 htre round-bottomed flask prepare a solution of 53-5 g. of o-toluidine in 170 ml. of 48 per cent, hydrobromic acid, cool to 5° by immersion in a bath of ice and salt. Diazotise by the gradual addition of a solution of 36 -5 g. of sodium nitrite in 50 ml. of water stopper the flask after each addition and shake until all red fumes are absorbed. Keep the temperature between 5° and 10°. When the diazotisation is complete, add 2 g. of copper powder or copper bronze, attach a reflux condenser to the flask, and heat very cautiously on a water bath. Immediately evolution of gas occurs, cool the flask in crushed ice unless the... 

Dissolve 200 g. of sodium nitrite in 400 ml. of water in a 2-litre beaker provided with an efficient mechanical stirrer, and add 40 g. of copper powder (either the precipitated powder or copper bronze which has been washed with a little ether). Suspend the fluoborate in about 200 ml. of water and add it slowly to the well-stirred mixture. Add 4-5 ml. of ether from time to time to break the froth. The reaction is complete when all the diazonium compound has been added. Transfer the mixture to a large flask and steam distil until no more solid passes over (about 5 litres of distillate). Filter off" the crystalline solid in the steam distillate and dry upon filter paper in the air this o-dinitrobenzene (very pale yellow crystals) has m.p. 116° (t.c., is practically pure) and weighs 29 g. It may be recrystallised from alcohol the recrystallised solid melts at 116-5°. 

The pure pigment may be obtained by heating phthalonitrile (4 mols) and copper bronze (1 atom) at 200-220° ... 

Pb02 graphite, platinum, or Pt on copper bronze, stainless steel (316), or iron... 

Copper and Copper Alloys Seamless copper, bronze, brass, copper-nickel-aUoy, and copper-silicon-aUoy pipe and tubing are produced by extrusion. Tubing is available in outside-diameter sizes from Vi6 to 16 in and in a range of wall thicknesses varying from 0.005 in for the smallest tubing to 0.75 in for the 16-in size. Tubing is usually specified by outside diameter and wall thickness. 

Ptienanthran-9-carboxyllc acid (2). A solution of o-aminophenylclnnamic add 1 (1.45 g, 6 rrml) In HCl (3.3 mL) and water (100 mL] was diazotized witti NaNOj (0.7 g, 10 mmol) In water (40 mL). To the diazonium salt was added copper bronze (1.0 g), the mocture was heated on a water bath to complete the reaction The while solid was filtered, dissolved in ammonia, filtered from insoluble material and the iHlrate was acidified. Crystallization from AcOH gave 0.5 g of 2 (40%), mp 2SO-ZS2 C... 

To the diazotized solution is added 35 g. (0.55 mole) of copper bronze (Note 2) which has been washed with ether. The stirrer is replaced by a long, efficient reflux condenser. A bath of ice water is prepared for cooling the flask when the reaction becomes... 

Reduced copper powder and various grades of copper bronze were used with practically the same results. 

Flexible metallic media are especially suitable for handling corrosive liquors and for high-temperature filtration. They have good durability and are inert to physical changes. Metallic media are fabricated in the form of screens, wire windings, or woven fabrics of steel, copper, bronze, nickel and different alloys. Perforated sheets and screens are used for coarse separation, as supports for filter cloths or as... 

Perfluoroalkylation can be accomplished via direct reaction of peifluoroalkyl halides and copper with aromatic substrates [232, 233, 234, 235, 236] Thus, perfluoroalkyl iodides or bromides react with functionalized benzenes m DMSO m the presence of copper bronze to give the corresponding perfluoroalkylated products directly in moderate to good yields [233] (equation 157) Mixtures of ortho, meta, and para isomers are obtained [232, 233], The use of acetic anhydride as solvent gives similar results [234, 235], Similarly, the direct reaction of perfluoroalkyl iodides and pyrroles with copper metal regiospecifically gives the 2-perfluoroalkylpyrroles [236] (equation 158). 

Ullman condensation of m-trifluoromethylaniline (13) with o-iodobenzoic acid in the presence of copper-bronze affords flu-fenamic acid (14). An analogous reaction of o-chlorobenzolc acid with 2,3-dimethylaniline (15) gives mefenamic acid (16) meclofenamic acid (18) is obtained by Ullman condensation employing 2,6-dlchloro-3-methylaniline (17). 

Phenoxyacetophenone A mixture consisting of 906 grams (6.66 mols) of m-hydroxy-acetophenone, 4,500 grams (26.6 mols) of bromobenzene, 996 grams (7.2 mols) of anhydrous potassium carbonate, and 300 grams of copper bronze was heated under reflux with... 

Natur Kupfer C is a good catalyst, but ordinary copper bronze may be used. 

Elimination of sulfur from methyl dibenzo[/),/]thiepin-10-carboxylatcs 15 (R2 = Me) can be achieved in moderate yields (39-55%) upon refluxing in diethyl phthalate in the presence of copper bronze.60 For the dibenzo[A,/]thiepin-10-carboxylic acids 15 (R2 = H), the loss of sulfur is accompanied by decarboxylation. Thus, treatment of these acids with copper bronze in refluxing quinoline for four hours gives the corresponding phenanthrenes 16 (R3 = H) in moderate yield (50%). However, the exposure time to high temperatures influences the product formation. Thus, the decarboxyiated dibenzothiepins are obtained after refluxing for only five minutes.60... 

When tribenzo[/>,with copper bronze and diethyl phthalate at 315°C for five hours, triphenylene (18) is obtained in 72% yield.4 Reductive desulfurization of 17 with Raney nickel in ethanol at room temperature gives l,l 2M -terphenyl (19) in 68% yield 4... 

Dibenzothiazepines lose sulfur on brief heating in diethyl phthalate in the presence of copper bronze to give phenanthridines 5.59 [Pg.335]

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