Metal impurities removal from reagents

MEK, 2-butanone, methyl ethyl ketone MEMO, 2-methoxyethoxymethylchloride Mercurochrome, mercury dibromofluorescein MES, 2-(7V-morpholino)-ethanesulfonic acid MESNA, Na 2-mercaptoethanesulfonate Metal impurities, by complexation by ion exchange resins by precipitation removal by extraction removal from reagents removal of lead removal of iron Methylarenes... 

The serious disadvantage of the use of the reactions of the chlorinated silica with organometallic compounds is caused by the high sensitivity of the Grignard reagent and organolithium compounds to the action of water, side reactions with the participation of surface siloxane bonds, and problems of removing metallic impurities from the surface of modified matrices. The difficulties mentioned explain why this approach to the synthesis of surface chemical compounds with Si-C bonds finds limited application. 

The extremely high reactivity of alkali metal solutions calls for the utmost care in their handling. They must not be exposed to the air indeed, solutions such as potassium in hexamethylphosphoric-triamide are pyrophoric. Moisture and other adsorbed impurities have to be meticulously removed from all surfaces that come in contact with these reagents. A relatively simple technique to achieve this goal is described elsewhere1415. 

Although precipitation constitutes the concluding part of the hydrometallurgical process flowsheet, the process is also put to use as a purification step in order to separate impurities. The different methods of precipitation are shown in Figure 5.25. The crystallization process is probably the simplest method to remove metals from solutions as compounds. No reagents are added, and the process simply involves the complete dissolution of the metal salt at a suitable temperature and pressure to obtain as high a metal content as possible. As the temperature is raised or lowered, depending on the particular system, the solubility of the metal salt in solution is exceeded and the salt precipitates or crystallizes... 

Sohd-phase scavengers can also be used both for removal of excess reagents and trace impurities, such as metal residues, for example palladium from cross-coupling reactions. A range of resins is available to remove a variety of metal residues, usually involving binding to a thiol or amino group. 

Citrate buffer and saline (MCB) solutions were preelectrolyzed for 24 h at — 1100 mV versus SCE to remove metal ion impurities. Acetonitrile (MCB) was redistilled and stored over molecular sieves. DTPA (Aldrich), triethylamine (Aldrich), and isobutylchloroformate (Sigma) were of the highest available purity. HSA (essentially globulin free) and rabbit IgG specific for HSA (Sigma) were obtained in the lyophilized form. Indium was obtained as anhydrous, ultrapure InCls (Alfa Products). All solutions were prepared from distilled/deionized HgO of at least 10 ft resistivity. Protein A from Staphylococcus aureus (SPA, Enzyme Center) was employed as an immunoadsorbent. It was obtained as a 10% (w/v) suspension with a 1.47 mg/ml binding capacity for immune complexes. 2-mercaptoethanol, sodium dodecyl sulfate, and acrylamide reagents were all of electrophoretic grade (Bio-Rad). 

Organic reagent removes impurities/metals from the pregnant leach solution according to reaction 7. RH is aldoxime or ketoxime (or a mixture). 

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