Copper exchange with

Butyrolactone reacts rapidly and reversibly with ammonia or an amine forming 4-hydroxybutyramides (175), which dissociate to the starting materials when heated. At high temperatures and pressures the hydroxybutyramides slowly and irreversibly dehydrate to pyrroHdinones (176). A copper-exchanged Y-2eohte (177) or magnesium siUcate (178) is said to accelerate this dehydration. 

A flow diagram for the system is shown in Figure 5. Feed gas is dried, and ammonia and sulfur compounds are removed to prevent the irreversible buildup of insoluble salts in the system. Water and soHds formed by trace ammonia and sulfur compounds are removed in the solvent maintenance section (96). The pretreated carbon monoxide feed gas enters the absorber where it is selectively absorbed by a countercurrent flow of solvent to form a carbon monoxide complex with the active copper salt. The carbon monoxide-rich solution flows from the bottom of the absorber to a flash vessel where physically absorbed gas species such as hydrogen, nitrogen, and methane are removed. The solution is then sent to the stripper where the carbon monoxide is released from the complex by heating and pressure reduction to about 0.15 MPa (1.5 atm). The solvent is stripped of residual carbon monoxide, heat-exchanged with the stripper feed, and pumped to the top of the absorber to complete the cycle. 

Corrosion. Copper and selected copper aHoys perform admirably in many hostile environments. Copper aHoys with the appropriate corrosion resistance characteristics are recommended for atmospheric exposure (architectural and builder s hardware), for use in fresh water supply (plumbing lines and fittings), in marine appHcations (desalination equipment and biofouling avoidance), for industrial and chemical plant equipment (heat exchangers and condensers), and for electrical/electronic appHcations (coimectors and semiconductor package lead-frames) (30) (see Packaging). 

The price of the compounds of copper varies with the price of the metal and the grade of the product. Average Commodities Exchange (COMEX)... 

The U-tube exchanger with copper tubes, cast-iron header, and other parts of carbon steel is used for water and steam services in office buildings, schools, hospitals, hotels, etc. Nonferrous tube sheets and admiralty or 90-10 copper-nickel tubes are the most frequently used substitute materials. These standard exchangers are available from a number of manufacturers at costs far below those of custom-built process-industry equipment. 

Figure 20-9 shows the negative effect of uninsulated heating elements on corrosion protection. In a 250-liter tank, an electric tube heating element with a 0.05-m surface area was screwed into the upper third without electrical separation, and in the lower third a tinned copper tube heat exchanger with a 0.61 -m surface area was built in. The Cu heat exchanger was short-circuited for measurements, as required. For cathodic protection, a potential-controlled protection system with impressed current anodes was installed between the two heating elements. The measurements were carried out with two different samples of water with different conductivities. 

Ammonia NH3 Corrosion of copper and zinc alloys by formation of complex soluble ion Cation exchange with hydrogen zeolite, chlorination, deaeration, mixed-bed demineralization... 

Copper (Cu) is deposited in boilers either by direct exchange with iron or by the hydrogen reduction of copper oxide during the corrosion of steel. 

Next, reductive amination (step 4 in scheme 1) was exchanged with copper catalyzed palladium coupling (step 2 in scheme 1). Atomic absorption analysis for palladium in RWJ-26240 samples prepared by scheme 2 indicated that the level of palladium was reduced to an acceptable level. This improvement may be due to the two reduction steps subsequent to the use of palladium in scheme 2.177 The final major modification to the reaction scheme was the substitution of NaBH4 for NaBH3CN. The yield of product (60%) was determined by HPLC (Method 2). Reductive alkylation with formalin/NaBH4 afforded a pharmaceutically acceptable drug substance. 

Commercial sodium zeolite sample (13X pellets, 1/16 ) was ion exchanged with a 0.015M copper(II) acetate solution at room temperature for 1 hour. After drying, the sample was ceramized at high temperature (1. ramp up to 800°C at 10°C/min 2. dwell... 

A number of pyridazines have been prepared by standard condensations of enediones with hydrazine but a general synthesis of the intermediate enediones is notable. This involved iodine-copper exchange of an iodoenone 3, followed by reaction of the resulting cuprate with acid chlorides. However, only a few of these enediones were actually converted into pyridazines <06OL1941>. 

In a similar reaction, Knochel and co-workers synthesized allylpyrimidine 63 through a magnesium-iodine exchange with iodopyrimidine 62, followed by copper (I) promoted coupling with allylbromide . 

Special consideration should be paid to metal complexes such as azomethine pigments (Sec. 2.10). At high temperatures, the yellow copper complex with the chemical constitution 10, incorporated in PVC, will exchange its chelated copper atoms with the metal atoms present in the application medium. Stabilizers containing barium/cadmium or lead produce yellow shades, while dibutyl tin thiogly-colate or other tin compounds produce a brilliant medium red. Color change is slow at low temperatures, but at 160°C the effect is rapid [108],... 

Finally, zinc-copper exchange by treatment of FG-RZnI with Me2Cu(CN)Li2 provides copper species that add smoothly to various alkynes and which can also be used to perform cyclization reactions (Scheme 2.48) [98]. 

Chlorpyrifos is stable to hydrolysis in the pH range of 5-6 (Mortland and Raman, 1967). However, in the presence of a Cu(lf) salt (i.e., cupric chloride) or when present as the exchangeable Cu(II) cation in montmorillonite clays, chlorpyrifos is completely hydrolyzed via first-order kinetics in <24 h at 20 °C. It was suggested that chlorpyrifos decomposition in the presence of Cu(II) was a result of coordination of molecules to the copper atom with subsequent cleavage of the side chain containing the phosphorus atom forming 3,5,6-trichloro-2-pyridinol and 0,0-ethyl-0-phosphorothioate (Mortland and Raman, 1967). 

Tunley, T. H. Birch, C. P. The recovery of copper from sulphate leach liquors by liquid ion exchange with LIX64N, National Institute of Metallurgy, Johannesburg, South Africa, Report No. 140904. 

While the mechanisms of these reactions have not been investigated in detail, it is likely that an intermediate copper(I) alkynyl is formed, which undergoes an alkynyl-halide exchange with the metal halide, resulting in the formation of the transition metal cr-alkynyl complex and a Cu(I) halide, which completes the catalytic cycle (Scheme l), ... 

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