Metal ations

Starting Material Metal- ation Meth- od0 Alkylation d.r.c 2/3 (6S/6R)... 

R1 Metal- ation Method Alkylation Agent (R2X) Yield (%) Md (c, solvent)d Yield (%) ... 

Active dissolution Passivity due to form- due, for example of metal. ation of an insoluble to O2 evolution... 

Most of ions do not interfere to the determination of P(V) or As(V). Big access of colored transition metals can be tolerated by using those metals solution as reference solution. It was already shown that high selectivity of the proposed method with respect to metal ions gave the opportunity to determine phosphoms in a number of nonferrous (brass, bronze) and ferrous alloys without preliminai y sepai ation. 

The method of stripping voltammetry (SV) is one of the most perspective methods in concentration range of thallium(I) determination of 10 -10 M. Achievement of high sensitivity of thallium(I) determination needs carrying out its additional concentration and sepai ation from other metals which ai e close by electrochemical properties. For these purposes it is offered to use a method of coprecipitation with collector. The combination of SV and a method of coprecipitation on a collector have shown that minimum detectable concentration can be decreased by 2-3 orders of magnitude. 

Method of Rh(III) - Ru(III) separation and isolation them from rai e and nonferrous metals based on formation of different charged complexes with varied stability has been proposed. Possibility of sepai ation of Ru(III), Rh(III), Pd(II), Pt(II) by water-soluble extractants from concentrated thiocyanate solutions has been displayed. Accelerated procedures of extraction-photometric determination of Rh(III), Ru(III) in solutions and waste products, which ai e chai acterized by high selectivity, availability, usage of non-toxic extractants have been worked out. 

The diffusion coefficients of cations in metal oxides are usually measured through the use of radioactive isotopes. Because of the friable nature of oxides it is exU emely difficult to use the sectioning technique employed for metal samples. The need for this can be avoided by the application of radioisotopes which emit radiation having a well established absorption law in matter. Isotopes which emit y radiation are very useful when the cation has a relatively high diffusion coefficient because of the long-range peneU ation of y rays. The absorption law is... 

In this chapter, we will review the effects of shock-wave deform.ation on material response after the completion of the shock cycle. The techniques and design parameters necessary to implement successful shock-recovery experiments in metallic and brittle solids will be discussed. The influence of shock parameters, including peak pressure and pulse duration, loading-rate effects, and the Bauschinger effect (in some shock-loaded materials) on postshock structure/property material behavior will be detailed. 

As first demonstrated by Stork,the metal enolate formed by metal-ammoni reduction of a conjugated enone or a ketol acetate can be alkylated in liquic ammonia. The reductive alkylation reaction is synthetically useful since ii permits alkylation of a ketone at the a-position other than the one at whicf thermodynamically controlled enolate salt formation occurs. Direct methyl-ation of 5a-androstan-17-ol-3-one occurs at C-2 whereas reductive methyl-... 

The largest industrial use of LiC2H is in the production of vitamin A, where it effects ethynyl-ation of methyl vinyl ketone to produce a key tertiary carbinol intermediate. The acetylides and dicarbides of the other alkali metals are prepared similarly. It is not always necessary to prepare this type of compound in liquid ammonia and, indeed, further substitution to give the bright red perlithiopropyne Li4C3 can be effected in hexane under reflux ... 

Ausfuhr,/. export(ation) elimination. ausfUhrbar, a. practicable, feasible exportable. Ausfuhrbewilligung, /. export license. ausfUhren, v.t. carry out, perform, execute amplify, explain clean, purge evacuate excrete export lead out erect Metal.) assay. 

Heimann and Vogtle [38] synthesized triesters of glycerol with different ether carboxylic acids with a short alkyl chain. They have found that these hydrophilic lipids, in contrast with the fatty acid glycerol triesters, give complex-ation with alkali and alkali earth metal cations in an analogy of crown ethers. 

For example, the sensitive imidoyl chloride moiety at the C-3 position of the pyrazinone scaffold is known to vmdergo Stille reactions with a variety of tetraaryltin reagents, generating the corresponding 3-substituted pyrazi-nones (Scheme 10) [26]. Furthermore, the transition-metal-catalyzed stannyl-ation at the C-3 position is also documented in the hterature, in view of cross-couphng with a variety of alkyl and (hetero)aryl hahdes [26]. However, this strategy is completely restricted to the C-3 position, while the Cl atom of C-5 position was found to be inert under these conditions. 

Using the above preformed catalysts, ethylene can be hydroaminated by primary and secondary amines under much lower pressures (3-55 atm) than those required for the reactions catalyzed by alkali metals (800-1200 atm). The example of N-ethyl-ation of piperidine has been described in full details in Organic Syntheses (Eq. 4.14) [120]. 

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