Sodium cation complexes acetone

In the case of cationic complexes with unsaturated macrocycles two molecules of nucleophile, such as ammonia, amines and alkoxides, add to carbon atoms of two inline groups. For example, the reaction of [Ni(Bzo[16]octaeneN4)](C104)2 (Table 106) with sodium methoxide or ethoxide yields the compounds (395),2860 while with secondary amines and diamines complexes of type (396) are obtained.28 1 The reaction of (396) with acetone at room temperature yields complex (397) where the enolate anion of acetone, MeC(0)CH2, replaces the diethylamide group (Scheme 58). 2862 The addition of molecules such as bis(2-hydroxyethyl)methylamine and bis(2-hydroxyethyl) sulfide, HOCH2CH2YCH2CH2OH (Y = NMe, S) results in the formation of derivatives which possess one more coordination site just above the plane of the macrocyclic donors (398).2863... 

Protection of C—C double bonds. The olefinic ligand of this cationic complex can be exchanged when heated above 20° with an excess of certain other olefins. Nicholas has used this property for protection of C—C double bonds, since the olefins can be regenerated by treatment of the complex with sodium iodide in acetone. The method is particularly useful for selective protection of dienes and polyenes. For example, the complex of norbomadiene undergoes electrophilic additions without isomerization to nortricyclane derivatives (equation I). The complex coordinates selectively with the less substituted and/or... 

Analogously, the reaction of rhenate pentacarbonyl anion [Re(CO)5] as its sodium salt, with cyclopropenylium cations [C3Ph3]X (X = BF4, PF6) in THF, at -80 °C, afforded the octahedral n-coordinated pentacarbonyl ( /-l,2,3-triphenylcyclopropenyl)rhenium complex in 60-73% yield (equation 195)26 269. The l3C NMR (acetone-, .) spectrum dis-... 

More recently, cationic intermediates have been observed in the Heck reactions of arene diazonium salts catalyzed by triolefinic macrocycle Pd(0) complexes [17,59], o-iodophenols and enoates to form new lactones [60], and o-iodophenols with olefins (the oxa-Heck reaction) [61 ]. In the first case ions were formed by oxidation of the analyte at the capillary, or by association of [NH4] or Na". In the two other cases ionization occurred through the more typical loss of a halide ligand. The oxa-Heck reaction provides a good example of how these experiments are typically performed and the type of information that can be obtained. The oxyarylations of olefins were performed in acetone, catalyzed by palladium, and required the presence of sodium carbonate as base. Samples from the reaction mixtures were diluted with acetonitrile and analyzed by ESI(+)-MS. Loss of iodide after oxidative addition of o-iodophenol to palladium afforded positively-charged intermediates. Species consistent with oxidative addition, such as [Pd(PPh3)2(C6H50)], and the formation of palladacycles of the type seen in Scheme 8 were observed. Based on this, a mechanism for the reaction was proposed (Scheme 8). 

The use of modifiers occasionally improves the extraction process. Water as extractant can be modified with organic solvents such as methanol, acetone or acetonitrile in low proportions (< 5%) in order to decrease its dielectric constant — and hence its polarity — without the need for a drastic temperature increase [37]. Also, an acid or base can be used to alter the pH in those cases where it significantly influences the extraetion yield [29,46]. On the other hand, surfactants facilitate the extraction of non-polar compounds by formation of micelles [47]. Modifiers are less frequently used with extractants other than water. One example is the addition of sodium acetate to methanol to extract organotins (OTs) the additive increases the efficiency in two ways, namely (a) acetate ion by complexing OTs and (b) sodium ion through cation exchange of OTs sorbed to the clay fraction of sediments [21]. 

Table IV also includes some values determined in methanol as the solvent these are very much higher (and, hence, also more accurate) than those in water, because the polyol competes with methanol, rather than with water, for outer-sphere positions on the cation. These figures explain why carbohydrates are soluble in methanol or ethanol containing high concentrations of calcium chloride, or even potassium acetate, and in such systems as lithium chloride in 2-methoxyethanol. ° Sugar derivatives that are soluble in non-hydroxylic solvents form complexes with cations in those solvents even more readily for example, methyl 2,3-0-isopropylidene-4-0-methyl-) -L-rhamnopyranoside (24) (but not its a anomer) will form a complex with sodium iodide in acetone, the Na" " ion coordinating to 0-1,0-2, and 0-3. In aqueous solution, the concentration of this complex would be negligible.

An anion complex, the hexaazidochromate(III), [Cr (N3)6] ", was isolated as the violet crystalline tetrabutylammonium salt. The complex is acetone soluble and decomposes at 255°C as with other azido complexes with large organic cations, no impact sensitivity was noted. To make it, chromium chloride hexahydrate was digested in 1 N sulfuric acid for 1 hr with excess dry sodium azide and then precipitated with a tetrabutylammonium salt [139]. 

The complex hexaazidoferrate(III), [Fe (N3)6] ", forms stable salts with large organic cations. These compounds are soluble in polar organic solvents, such as acetone, nitrobenzene, dimethylformamide, and pyridine contact with water aquates the complex. Isolated were the tris-(trimethylbenzylammonium) salt, MP 107°C, the tris-(p-nitrobenzylpyridinium) salt, MP 112°C and the sodium bis-(tetramethylammonium) salt, MP 270°C with deflagration [155]. 

---