Lithium structures

The polymerization of 1,4-butadiene and related conjugated dienes in polar media was discussed earlier. The major focus of this part of the review will be devoted to the polymerization of 1,3-butadiene and iso-prene in hydrocarbon media, with emphasis on the allylic lithium structure and reactivity. 

As part of an ongoing effort to extend the scope of this methodology, we investigated the influence of both the a,/3-unsaturated aldehyde structure and the organo-lithium structure on the formation of the tandem product. Aliphatic a,/3-unsaturated aldehydes as well as aliphatic lithium reagents failed to afford the tandem reaction,... 

The next sections describe three reactor studies with emphasis on the lithium-structure compatibility. HYLIFE is a liquid metal wall (LMW) ICF reactor considered here for electricity production. It has also been adapted to fissile fuel production ( 5). The Tandem Mirror Reactor (TMR) Cauldron Blanket Module is an MCF concept designed to produce hydrogen. The TMR Heat Pipe Blanket Module is designed to produce either hydrogen or electricity. All three studies emphasize materials compatibility with lithium. Tritium recovery techniques and two aspects of lead-lithium liquids are also discussed. 

Lithium-Structure Compatibility. One of the critical chemistry problems of HYLIFE is the compatibility of structural alloys with the molten liquid of the jet array. Two candidate liquid metals are lithium and Pbg3Lij 7. High-Z metal (such as lead from target debris) will enter the liquid metal and may affect the compatibility. The structural alloy selected in the HYLIFE study is Cr-1 Mo, a ferritic steel. The carbides usually present in this steel are M3C (cementite) and M2C, where M is primarily Fe. Both of these carbides are unstable in lithium. M3C is usually present as platelets within pearlite, the eutectoid structure in pearlitic steel. The most common microstructure for the 2 4 Cr-1 Mo steel is large grains of ferrite with small islands of pearlite. M2C is present as a fine spray of precipitate within large ferrite grains. Lithium... 

My friends thought I d gone crazy — leaving the respected field of experimental physical organic chemistry for such computational fantasies. Who could believe such weird results While easy to understand now, the ionic bonding of lithium compounds follows structural principles different from covalent bonding. But it was not apparent in 1975 that lithium structures shouldn t conform to van t Hoff s rules. 

Lawson, D.F. Hergenrother, W.L. Kerns, M.J. Tertiary Amines Containing Side-chain Organo-lithium Structures and Method for the Preparation Thereof. U.S. Patent 5,912,343, Jun 15, 1999 Bridgestone. 

Similarly to the lithium structures, the coordination number of the central ion gradually decreases from ten in NaLa(S04)2 to eight in the isostructural compounds NaEr(S04) and a-NaTm(S04)2. 

TMEDA, which was determined by single-crystal X-ray structural analysis as a monomeric chelate enolate lithium structure [60]. Hydrolysis of the isolated intermediate 36 afforded its corresponding gc/M-bis(trimethylsilyl) cyclopentenones derivative 38 containing a stable enol moiety in a quantitative yield. No double-acylated product was obtained even when two equivalents of ArCOCl were used. 

Give the structure of an ester that will yield a mixture contain mg equimolar amounts of 1 propanol and 2 propanol on reduction with lithium aluminum hydride... 

Mescaline a hallucinogenic amine obtained from the peyote cactus has been synthesized in two steps from 3 4 5 trimethoxybenzyl bromide The first step is nucleophilic substitution by sodium cyanide The second step is a lithium aluminum hydnde reduction What is the structure of mescaline" ... 

In each of the following reactions an amine or a lithium amide derivative reacts with an aryl halide Give the structure of the expected product and specify the mechanism by which it is formed... 

An effect which is frequently encountered in oxide catalysts is that of promoters on the activity. An example of this is the small addition of lidrium oxide, Li20 which promotes, or increases, the catalytic activity of dre alkaline earth oxide BaO. Although little is known about the exact role of lithium on the surface structure of BaO, it would seem plausible that this effect is due to the introduction of more oxygen vacancies on the surface. This effect is well known in the chemistry of solid oxides. For example, the addition of lithium oxide to nickel oxide, in which a solid solution is formed, causes an increase in the concentration of dre major point defect which is the Ni + ion. Since the valency of dre cation in dre alkaline earth oxides can only take the value two the incorporation of lithium oxide in solid solution can only lead to oxygen vacaircy formation. Schematic equations for the two processes are... 

No fewer than 14 pure metals have densities se4.5 Mg (see Table 10.1). Of these, titanium, aluminium and magnesium are in common use as structural materials. Beryllium is difficult to work and is toxic, but it is used in moderate quantities for heat shields and structural members in rockets. Lithium is used as an alloying element in aluminium to lower its density and save weight on airframes. Yttrium has an excellent set of properties and, although scarce, may eventually find applications in the nuclear-powered aircraft project. But the majority are unsuitable for structural use because they are chemically reactive or have low melting points." ... 

Good results are obtained with oxide-coated valve metals as anode materials. These electrically conducting ceramic coatings of p-conducting spinel-ferrite (e.g., cobalt, nickel and lithium ferrites) have very low consumption rates. Lithium ferrite has proved particularly effective because it possesses excellent adhesion on titanium and niobium [26]. In addition, doping the perovskite structure with monovalent lithium ions provides good electrical conductivity for anodic reactions. Anodes produced in this way are distributed under the trade name Lida [27]. The consumption rate in seawater is given as 10 g A ar and in fresh water is... 

EXAFS is a nondestructive, element-specific spectroscopic technique with application to all elements from lithium to uranium. It is employed as a direct probe of the atomic environment of an X-ray absorbing element and provides chemical bonding information. Although EXAFS is primarily used to determine the local structure of bulk solids (e.g., crystalline and amorphous materials), solid surfaces, and interfaces, its use is not limited to the solid state. As a structural tool, EXAFS complements the familiar X-ray diffraction technique, which is applicable only to crystalline solids. EXAFS provides an atomic-scale perspective about the X-ray absorbing element in terms of the numbers, types, and interatomic distances of neighboring atoms. 

Polymers containing 90-98% of a c 5-1,4-structure can be produced using Ziegler-Natta catalyst systems based on titanium, cobalt or nickel compounds in conjuction with reducing agents such as aluminium alkyls or alkyl halides. Useful rubbers may also be obtained by using lithium alkyl catalysts but in which the cis content is as low as 44%. 

Polystyrene produced by free-radical polymerisation techniques is part syndio-tactic and part atactic in structure and therefore amorphous. In 1955 Natta and his co-workers reported the preparation of substantially isotactic polystyrene using aluminium alkyl-titanium halide catalyst complexes. Similar systems were also patented by Ziegler at about the same time. The use of n-butyl-lithium as a catalyst has been described. Whereas at room temperature atactic polymers are produced, polymerisation at -30°C leads to isotactic polymer, with a narrow molecular weight distribution. 

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