Metal addition cation exchange

Sodium nitrite has been synthesized by a number of chemical reactions involving the reduction of sodium nitrate [7631-99-4] NaNO. These include exposure to heat, light, and ionizing radiation (2), addition of lead metal to fused sodium nitrate at 400—450°C (2), reaction of the nitrate in the presence of sodium ferrate and nitric oxide at - 400° C (2), contacting molten sodium nitrate with hydrogen (7), and electrolytic reduction of sodium nitrate in a cell having a cation-exchange membrane, rhodium-plated titanium anode, and lead cathode (8). 

Also, nylon-6 waste may be hydrolyzed in the presence of an aqueous alkali metal hydroxide or acid5 to produce an alkali metal or acid salt of 6-aminocaproic acid (ACA). The reaction of nylon-6 waste with dilute hydrochloric acid is rapid at 90- 100°C. The reaction mixture is poured into water to form a dilute aqueous solution of the ACA salt. Filtration is used to remove undissolved impurities such as pigments, additives, and fillers followed by treatment of the acid solution with a strong cation exchange resin. A sulfonic acid cationic exchanger absorbs ACA salt and pure ACA is eluted with ammonium hydroxide to form a dilute aqueous solution. Pure ACA is obtained by crystallization of die solution. 

Removal of inorganic interferences, particularly the removal of bromide interference in seawater by fivefold dilution of the sample, the removal of nitrate by addition of sulfamic acid, and the removal of metals by passage through Amberlite IR 120 cation exchange resin. 

Treatment of lithium enolate species, such as 7, with a variety of metal halide species produces enolates with different reactivities in particular, diethylaluminum(IH) and copper(I) species have been found to profoundly alter stereodifferentiation in reactions of iron acyl enolates (see Section D.1.3.4.2.5.1.). It has not been established whether complex formation or discrete ti ansmetalation occurs usually, a temperature increase from — 78 °C to — 42 °C is required for maximum effect, suggesting that cation exchange is responsible. In some cases, such additives exert an influence at —78 °C13, and this has been attributed to simple Lewis acid-type interactions with the substrate instead of transmetalation of the enolate species. For simplicity, when such additives are allowed to react with enolate species at temperatures of — 42 =C and above prior to the addition of other reagents, the process shall be referred to as transmetalation. 

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