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Rieke metals

Investigation of the configurational stability of allylmetals 2a, prepared by means of Rieke metals from geometrically pure l-chloro-2-decenes 1 a in THF, showed that the (Z)- and (ZT)-lithium, -sodium, and -potassium derivatives preserve the configuration of the precursors to a preparatively useful extent below — 90°C, — 50°C, and >0°C, respectively. For the pairs of 3,7-dimethyl-2,6-octadienyl derivatives (Z)- and ( )-2b, which differ less in their thermodynamic stability, the respective temperatures are — 60 °C, — 40 °C and >0°C124. [Pg.230]

Another classic system - metallic Li and naphthalene (or biphenyl) as electron-carrier - is also prepared in N N.N. N -tetramethylethylenediamine (tmeda) and toluene mixture by US treatment. This system serves for obtaining highly active Rieke metals [708],... [Pg.292]

The majority of synthetic approaches to binary carbonyls involve car-bonylation of solutions of metal salts in the presence of a suitable reduc-tant (Figure 3.11). Nickel and iron are the only metals that will react readily with CO, and even iron requires the use of high temperatures (420 K) and pressures (100 atm). Some other metals (Mo, W, Co, Ru) in highly activated form ( Rieke metals ) will also react with CO under higher temperatures and pressures. [Pg.53]

University of Nebraska and Rieke Metals, Inc., Lincoln, Nebraska... [Pg.53]

Rieke metal has broad application in organic synthesis that requires an active metal of low valence, such as the McMurry Coupling (Cr) and the Reformatsky Reaction (Zn). [Pg.2389]

Other references related to the Rieke metal are cited in the literature. " ... [Pg.2390]

Finely divided, highly reactive, Rieke metal powders are normally prepared by reducing metal halides with potassium metal in refluxing tetra-hydrofuran. This clearly represents a laboratory safety hazard but sonication can produce these same powders under much milder conditions using the less reactive lithium metal at ambient temperatures [12]. Thus the preparation of Rieke copper, which normally requires an 8 h reflux with potassium in THF, can be achieved in less than 40 min at room temperature with sonication (Scheme 10.3). [Pg.337]

I A new method was introduced for the preparation of highly reactive, finely dispersed metals by reduction of their halides with the aid of alkali metals. These metals are named Rieke metals (such as Rieke magnesium. Mg, Rieke zinc, Zn, etc.) after the inventor of the process [53-56]. Their reactivity is extremely high and reactions have been made possible which were simply unthinkable before. [Pg.97]

Rieke Magnesium. Rieke metals are highly reactive metal powders prepared by reduction of the corresponding halide by potassium in a suitable solvent. The first publication in this field by Rieke and co-workers appeared in 1972 [38]. For reviews see [39]. [Pg.174]

The activated zinc will also react rapidly with a-chloroesters in THF. However, the yields are not as high and generally are in the 70-80% range. The Reformatsky reagent can be prepared separately and then added dropwise to the carbonyl compound at room temperature. In addition, the Reformatsky reagent in THF or diethyl ether can be purchased from Rieke Metals, LLC. The shelf life of the Reformatsky reagent is limited and slowly decomposes over a period of 10-20 days even if it is stored in a refrigerator. The best results are obtained if it is used as soon as possible. [Pg.53]

A three-necked flask, fitted with a reflux condenser and septa, was purged with Ar for 15 min. The Rieke zinc/THF slurry (purchased from Rieke Metals, LLC,... [Pg.111]

The chemical modification of cross-linked polymers has received considerable interest since the discovery of Merrifield resin and its use in peptide synthesis. Cross-linked polystyrene resins have been mainstays in solid-phase synthesis and organic synthesis. Few successful examples of functionalizing cross-linked polystyrene resins have been reported, as the insoluble cross-linked polymers are particularly resistant to reagents. Rieke metals have been found to be an effective tool for the fimctionalization of cross-linked polymers. [Pg.386]

The parent tetrakis(2-methoxyphenyl)ethene can be prepared in 73% yield firom 2,2 -dimethoxybenzophenone (Rieke Metals, Inc., Lincoln, Nebraska) in the same way, except the McMurry reduction is typically complete within 10-11 h. [Pg.192]

Polythiophene Sensors (8,49, 50). In order to gain information concerning the type of interaction between polymer sensing material and analyte vapor, we have performed preliminary studies with a non-doped regioregular poly(3-hexylthiophene) (Rieke Metals Inc.) sensor, since the conformation of polythiophene chains is known to be potentially sensitive to external stimuli which are frequently accompanied by measurable changes in their Vis/UV spectra (60). [Pg.202]


See other pages where Rieke metals is mentioned: [Pg.231]    [Pg.240]    [Pg.95]    [Pg.131]    [Pg.385]    [Pg.87]    [Pg.53]    [Pg.527]    [Pg.539]    [Pg.260]    [Pg.55]    [Pg.177]    [Pg.727]    [Pg.2034]    [Pg.2388]    [Pg.2388]    [Pg.2390]    [Pg.1]    [Pg.11]    [Pg.14]    [Pg.17]    [Pg.108]    [Pg.287]    [Pg.2019]    [Pg.160]   
See also in sourсe #XX -- [ Pg.240 ]

See also in sourсe #XX -- [ Pg.240 ]




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