Bases halides

The boronic acid 2 is first converted to an activated species 8 containing a tetravalent boron center by reaction with a base. Halides or triflates (OTf = trilluoromethanesulfonate) are used as coupling partners R-X for the boronic acids. In many cases the rate-limiting step is the oxidative addition. With respect to the leaving group X, the rate decreases in the order ... 

Jayaraman, S., Haggie, P., Wachter, R. M., Remington, S. J. and Verkman, A. S. (2000). Mechanism and cellular applications of a green fluorescent protein-based halide sensor. J. Biol. Chem. 275, 6047-50. 

BR with narrow MMDs (Mw/Mn > 3.5) and a low solution viscosity can also be obtained by the use of a multi-component catalyst system which comprises the following six components (1) Nd-salt, (2) additive for the improvement of Nd-solubility, (3) aluminum-based halide donor, (4) alumoxane, (5) aluminum (hydrido) alkyl, and (6) diene. The solubility of the Nd-salt is improved by acetylacetone, tetrahydrofuran, pyridine, N,N-dimethylformamide, thiophene, diphenylether, triethylamine, organo-phosphoric compounds and mono- or bivalent alcohols (component 2). The catalyst components are prereacted for at least 30 seconds at 20 - 80 °C. Catalyst aging is preferably performed in the presence of a small amount of diene [397,398 ]. As the additives employed for the increase of the solubility of Nd salts exhibit electron-donating properties it can be equally well speculated that poisoning of selective catalyst sites favors the formation of polymers with a low PDI. 

Nakazawa and Tanaka described a potentiometric titration of salts of organic bases in non-aqueous solvents with the addition of bismuth nitrate [16], The base halide or hydrohalide (0.7 mequiv.) is dissolved in 40 mL of anhydrous acetic acid, and then 40 mL of 1,4-dioxane and 2.5 mL of 5% Bi(N03)3 solution in acetic acid are added. The Bi(N03)3 prevents interference by the halide. The solution is titrated to a potentiometric endpoint with 0.1 M HC104 (a blank titration is also carried out). Results of purity assays of acetylcholine chloride and other compounds were tabulated, and it was found that the coefficient of variation was 0.18%. 

Alkyl halide Base Alkene Conjugate acid of base Halide... 

It is a remarkable feature that the experimental data obtained in Na+-based halides had led Smirnov to the conclusion that the minimum complexation ability takes place in chloride melts [81], but it is not so for potassium- and caesium-based halides. Therefore, the stability of alkali metal cation-halide ion is dependent not only on the anion properties but also on those of the cation. In the potassium and caesium halides this reason shifts the minimum of the complexation ability to the bromide melts, which makes these media more acidic than the corresponding chlorides and iodides. 

Galietta. L.J.V. Haggle. P.M. Verkman. A.S. Green fluorescent protein-based halide indicators with improved chloride and iodide affinities. FEBS Lett. 2001, 499 (3). 220-224. 

It has been found that oxide solubilities (pP) are related to eation radius. For Na- and K-based halide melts, a plot for solubility products expressed in molar fractions is described by the following equation ... 

The Mannich reaction-based halide-promoted cyclization of [ C]methylene iminium ions, generated in situ from H CH0 and appropriate 3,4-doubly or triply unsaturated butylamines (Overman reaction) offers an alternate access to C4-functionalized [ C]-piperidines and tetrahydro[ C]pyridines, as illustrated in Figure 5.48. The observed... 

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