Copper recrystallization temperature

Additions of cadmium (0.05—1.3%) to copper raise the recrystallization temperature and improve the mechanical properties, especially in cold-worked conditions, with relatively Htde reduction in conductivity. Copper containing 0.07% cadmium is used in automotive cooling fins, heavy-duty radiators, motor commutators, and electric terminals. 

Effect of Thermal History. Many of the impurities present in commercial copper are in concentrations above the soHd solubihty at low (eg, 300°C) temperatures. Other impurities oxidize in oxygen-bearing copper to form stable oxides at lower temperatures. Hence, because the recrystallization kinetics are influenced primarily by solute atoms in the crystal lattice, the recrystallization temperature is extremely dependent on the thermal treatment prior to cold deformation. 

Minor additions of arsenic (0.02—0.5%) to copper (qv) and copper alloys (qv) raise the recrystallization temperature and improve corrosion resistance. In some brass alloys, small amounts of arsenic inhibit dezincification (22), and minimize season cracking. 

The pentafluorophenylcopper tetramer is usually analytically pure as isolated and melts at 200° with decomposition. If any significant decomposition occurs during the final drying, the product can be purified by dissolution in ether, filtration to remove copper metal, and precipitation by addition of hexane. It can also be recrystallized from benzene. When kept in a sealed container under nitrogen at room temperature, pentafluorophenyl copper tetramer appears to be stable for reasonable periods. It can be stored indefinitely at -78° under an atmosphere of carbon dioxide. 

DBpD was prepared by slowly heating a mixture of o-chlorophenol (480 mmoles), potassium carbonate (240 mmoles), and purified copper powder (50 mmoles) in a 500-ml Erlenmeyer flask to 160°-180°C and maintaining this temperature for 6 hours. DBpD, which sublimed to the walls of the flask as it was formed, was recovered by scraping and was recrystallized from absolute ethanol (14% yield white needles, mp 119°-120°C reported 120°-122°C (7) elemental analyses—calcd. C = 78.26, H = 4.34, found C = 77.98, H = 4.48). 

As an additional example of high practical significance, we refer here to copper depKJsits when used in microelectronics, mirrors, and other optical applications. Those deposits have been observed to soften in time even when stored at room temperature for only 4 to 6 weeks. Also, mirrors and other precision objects made of copper will undergo surface deformation after a few months. This type of degradation can be counterbalanced by a suitable metal overcoating. Another, not always practical way is heat treatment to about 300°C. These phenomena are the direct results of microstructural instabilities, often referred to as recrystallization in the copper. It is worth stressing that recrystallization is not limited to copper (5). 

A reactor was charged with 500 ml of acetone, 4-bromophenylacetylene (225 mmol), copper chloride (14 mmol), and N, N, N, A -tetramethylethylenediamine (14 mmol) and stirred for 1 hour at ambient temperature while bubbling in oxygen. The mixture was then concentrated, precipitated in 5% hydrochloric acid, and a light-yellow solid isolated. The solid was recrystallized in CHCI3, dried, and 39.8 g of product isolated as a light-yellow solid product, mp = 264-265°C. 

A reactor was charged with the step 3 product (88 mmol), p-toluidine (88 mmol), and copper chloride (22 mmol) and then stirred for 5 hours at 200°C. It was cooled to ambient temperature and then dissolved in CHCI3 and washed several times with 5% hydrochloric acid, water, and then dried with MgSOzt- Thereafter the mixture was concentrated, the residue purified by recrystallization in ethyl acetate, and... 

To the reaction mixture 450 g. of zinc dust (Note 2) is added in portions of about 10 g. with vigorous stirring. The rate of addition is regulated so that the temperature never rises above 6o°. After the addition is complete (Note 3), the mixture is refluxed for two to three hours on a hot plate until the unreacted zinc dust collects in balls. The hot solution is then poured through a fine copper sieve, with stirring, into 30 1. of ice water. The crude product which separates is contaminated with zinc (Note 4). On recrystallization from 1500 cc. of 95 per cent ethyl alcohol, 360-390 g. of 2,4-dimethyl-3-acetyl-5-carbethoxypyrrole (m.p. 143-1440) is obtained (55-60 per cent of the theoretical amount based on the ethyl acetoacetate used) (Note 5). A second recrystallization may be necessary to secure a perfectly white product, but the product of the first recrystallization is sufficiently pure for conversion to kryptopyrrole. 

An aqueous solution (lOmL) of copper(II) acetate monohydrate (2.2mmol) was added to a methanolic solution (40mL) of H3L (1 mmol). The solution was allowed to stand for several hours at room temperature. The crude complex precipitated was collected by suction filtration and dried. Yield 90%. The complex was recrystallized from hot methanol-dimethylformamide (1 1) to give dark green crystals of formula [Cu2L(OCH3)]-DMF. Yield ca. 30%. 

To a solution of 1.14 g of 3-methyl-trans-4a-cisoid-4a,5a-cis-5a-l,4a,5,5a,10b,10c-hexahydro-7-dioxino[5,4-a]cyclopenta[b]benzofuranyl-methanol in 10 ml of dimethoxyethane cooled in an ice bath was added 0.43 ml of anhydrous pyridine and 0.38 ml ofthionyl chloride, and the mixture was stirred for 3 hours at room temperature. After addition of ether to the reaction mixture, the precipitate was filtered, and water was added to the filtrate and the mixture was extracted three times with ether. The extract was washed with aqueous saturated solution of copper sulfate, water, aqueous saturated solution of sodium hydrogen carbonate and aqueous saturated solution of sodium chloride, dried, and concentrated to give 1.2 g of crude crystals. The crude crystals were recrystallized from ethyl acetate-hexane to yield 1 g of the pure titled chloride (m.p. 94-95°C, yield 83%). 

If instead of a mild Lewis base such as THF a strong Lewis base such as pyridine is used in the reaction between copper acetate and dtbp-H, one obtains yet another type of one-dimensional polymeric phosphate (Chart 16).36c Recrystallization of this water-bridged polymer in a DMSO/ THF/CH3OH mixture results in the transformation of the polymer to a more stable tetranuclear copper cluster [Cu4-(u3-OH)2(dtbp)e(py)2] in about 60% yield (Figure 3). This observation demonstrates that even simple recrystallization can bring about an interesting structural transformation at room temperature in such materials. 

Zinc is very widely used metal in a variety of environments. The strength and hardness of zinc are greater than those of tin or lead and are less than those of aluminum or copper. It is not possible to use pure zinc in applications involving applied stress due to its low creep resistance. Zinc recrystallizes rapidly after deformation at laboratory temperature and hence cannot be work-hardened at laboratory temperature. By alloying with other metals the temperature of recrystallization and the creep resistance can be increased to acceptable levels. The alloys of commercial importance are ... 

Copper(II) acetate monohydrate (0.6 g, 0.003 mole) dissolved in water (50 mL) is added to a solution of H4daen (1.0 g, 0.003 mole) in dichloromethane (50 mL), and the two phases are intimately mixed by stirring for 1.5 hours at room temperature. The dichloromethane layer first becomes deep green and then purple. The mixture is poured into a separatory funnel and the lower dichloromethane layer is collected and evaporated under reduced pressure to leave a purple gum. This gum is dissolved in a small volume of chloroform and the resulting solution is eluted with chloroform down a column of neutral activated alumina (50 g). ( Caution. Chloroform is a suspected carcinogen. It should be handled in a well-ventilated hood, with inert gloves to avoid inhalation and skin contact.) The purple fraction is collected, and removal of the solvent by evaporation under reduced pressure leaves a purple solid that is recrystallized... 

Procedure Add 20 grams of picryl chloride and 400 milliliters of ethylene dichloride to a 1-liter flask equipped with a stirrer, thermometer, and condenser. Then stir the mixture to fully dissolve the picryl chloride. Afterwards, heat the mixture to 75 Celsius. When the temperature of the mixture reaches 75 Celsius, slowly add in small portions, 8.8 grams of copper powder while rapidly stirring the picryl chloride mixture. After the addition of tire copper powder, reflux the reaction mixture at 84 Celsius for two hours. After which, remove the heat source, and allow the mixture to cool to room temperature. Then filter-off the precipitated product, wash with 400 milliliters of water, and then vacuum dry or air-dry the product. Then recrystallize the product from 100 milliliters of acetone, and then wash with 400 milliliters of water. Then vacuum dry or air-dry the product. 

A mixture of 35 g. of copper sulfate, 100 g. of sodium bromide, 30 g, of copper turnings, 33 g. of concentrated sulfuric acid, and 300 ml. of water is heated to boiling. After the color is gone from the solution, 40 g. (0.29 mole) of anthranilic acid is added and the mixture cooled to below 10°. An aqueous solution containing 22 g. (0.32 mole) of sodium nitrite is added dropwise, the temperature of the reaction mixture being held below 10°, and the mixture allowed to stand at room temperature for several hours. Filtration of the mixture gives a 90 yield of crude o-bromobenzoic acid. The pure acid, m.p. 150°, is obtained in 82% yield by recrystallization from hot water. 

The first step in any kinetic study is to identify all the products and intermediates of the reaction. Dehydration often involves several distinct steps which may be very dependent upon reaction conditions, e,g, copper sulfate pentahydrate may yield trihydrate and/or monohydrate [29,30], Metastable intermediates may be formed, e,g, amorphous magnesium carbonate produced on dehydration undergoes [18] exothermic recrystallization at higher temperatures,... 

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