K+C Na

Figure 9.41 Comparison of Raman spectra of AHMo50i6(H20)H20m A = (a) NH4+ (b) K+ (c) Na+ and (d) compound spectrum in aqueous solutions. (Reproduced from A. Fadini and F-M. Schnepel, Vibrational Spectroscopy Methods and Applications, Ellis Horwood, Chichester, 1989.)...

Tbe mass-transfer coefficients k c and /cf by definition are equal to tbe ratios of tbe molal mass flux Na to tbe concentration driving forces p — Pi) and (Ci — c) respectively. An alternative expression for tbe rate of transfer in dilute systems is given by... 

G. Pitselis, P. Petrolekas, and C.G. Vayenas, Electrochemical Promotion of NH3 decomposition over Fe catalyst films interfaced with K+ and Na+ conductors, Ionics 3, 110-117(1997). 

These chemically reactive phases are prepared by slow cooling of melts with the appropriate composition under an inert atmosphere or vacuum. Equilibrium is slow to be attained at the low temperatures necessary to prevent dissociation at 6.9°C Na2K dissociates into a (solid solution of K in Na) and liquid (60/40 Na/K). The KjCs and K7CSJ phases are even less stable and result from cooling mixtures of the elements of the desired stoichiometry to — 100°C in a metal beaker under argon. ... 

Hydride reduction of 4-fert-butylcyclohexanone 3 shows a preference for axial addition [axial additioniequatorial addition = 91-88.5 9-11.5 (LiAIH ) [16,17, 50, 51] or 87-86 13-14 (NaBH )] [50, 52]. Addition of acetyhde anion, Na(Li or K) C=CH, also showed a similar axial preference [14, 15, 53]. 

UB Sleytr, H Bayley, M Sara, A Breitwieser, S Ktipcti, C Mader, S Weigert, PM Unger, P Messner, B Jahn-Schmid, B Schuster, D Pum, K Douglas, NA Clark, IT Moore, TA Win-ningham, S Levy, I Prithsen, J Pankovc, P Beale, HP Gillis, DA Choutov, KP Martin. FEMS Microbiol Rev 20 151-175, 1997. 

More severe conditions, 35 ml of 35% methanolic KOH added to 10 mL extract in EtOAc and shaken for 20 min at 50°C, are necessary for the total conversion of bixin, an ester of a carotenoid acid, to norbixin in snacks. Since saponification yields the norbixin salt (K or Na, depending on the alkali) that is soluble in the aqueous phase, the pH should be decreased to 3.5 or even lower to allow extraction of the protonated norbixin by EtOAc and diethyl ether. ... 

Figure 1.140. The dependence of concentration of K+, Na, Ca + and HaSiOa in equilibrium with common alteration minerals (K-feldspar, Na-feldspar, quartz) with temperature (Shikazono, 1988b). Thermochemical data used for the calculations are from Helgeson (1969). Calculation method is given in Shikazono (1978a). Chloride concentration in hydrothermal solution is assumed to be 1 mol/kg H2O. A-B Na+ concentration in solution in equilibrium with low albite and adularia. C-D K+ concentration in solution in equilibrium with low albite and adularia. E-F H4Si04 concentration in solution in equilibrium with quartz. G-H Ca " " concentration in solution in equilibrium with low albite and anorthite.

Transfer hydrogenolysis of benzyl acetate was studied on Pd/C at room temperature using different formate salts.244 Hydrogen-donating abilities were found to depend on the counterion K+ > NH4 + > Na+ > Li+ > H+. Formate ion is the active species in this reaction. Adsorption of the formate ion on the Pd metal surface leads to dissociative chemisorption resulting in the formation of PdH- and C02. The kinetic isotope effect proves that the dissociative chemisorption of formate is the rate-limiting step. The adsorption and the surface reaction of benzyl acetate occurs very rapidly. 

The alternation of temperature in a hydrothermal reaction was demonstrated to be crucial in changing the crystal phases or morphologies of nanomaterials. In the case of K2Cr207, when the reaction temperature was increased to 180 °C, K-OMS-2 microspheres consisting of nanoneedles were synthesized in contrast to the nanoduster arrays composed of tetragonal prism nanorods synthesized at 120 °C (Figure 8.1a-c). In the case of Na2Cr207, when the reaction temperature was 100 °C, Na-OMS-2 phase was formed. However, when the reaction temperature was... 

Information on structure and bonding in alkali metal species with group 14, 15, and 16 ligands has been mainly focused on lithium derivatives the heavier analogs have been dealt with to a much-reduced extent. As mentioned in a 2004 review article,11 a search in the Cambridge Structural Database (CSD) revealed 778 structures with an Li-C bond, but only 197 with an Na-C, 235 with a K-C, 57 with an Rb-C, and just 31 with a Cs-C bond. 

Interestingly, more structures with a K-C than Na-C bond are known, despite the increasing reactivity of the compounds as descending the group of alkali metals. As frequently observed, K, Rb, and Cs compounds display somewhat similar chemistry, which typically differs from that of the lithium analogs. Sodium, in many instances, adopts a chemistry that resembles more that of lithium than the heavier congeners, most likely a function of the ionic size. 

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