Lithium special

Breslow supported this suggestion by demonstrating that the cycloaddition can be further accelerated by adding anti cliaotropic salts such as lithium chloride, whereas chaotropic salts such as guanidium chloride led to a retardation " "" ". On the basis of these experiments Breslow excluded all other possible explanations for the special effect of water on the Diels-Alder reaction " . 

Common catalyst compositions contain oxides or ionic forms of platinum, nickel, copper, cobalt, or palladium which are often present as mixtures of more than one metal. Metal hydrides, such as lithium aluminum hydride [16853-85-3] or sodium borohydride [16940-66-2] can also be used to reduce aldehydes. Depending on additional functionahties that may be present in the aldehyde molecule, specialized reducing reagents such as trimethoxyalurninum hydride or alkylboranes (less reactive and more selective) may be used. Other less industrially significant reduction procedures such as the Clemmensen reduction or the modified Wolff-Kishner reduction exist as well. 

Because of the special stabiHty of the hexafluoroarsenate ion, there are a number of appHcations of hexafluoroarsenates. For example, onium hexafluoroarsenates (33) have been described as photoinitiators in the hardening of epoxy resins (qv). Lithium hexafluoroarsenate [29935-35-1] has been used as an electrolyte in lithium batteries (qv). Hexafluoroarsenates, especially alkaH and alkaline-earth metal salts or substituted ammonium salts, have been reported (34) to be effective as herbicides (qv). Potassium hexafluoroarsenate [17029-22-0] has been reported (35) to be particularly effective against prickly pear. However, environmental and regulatory concerns have severely limited these appHcations. 

Economic Aspects. Lithium metal is available commercially in ingots, special shapes, shot, and dispersions. Ingots are sold in 0.11-, 0.23-, 0.45-, and 0.91-kg sizes. Special shapes include foil, wire, and rod. Lithium is available in hermetically sealed copper cartridges and in sealed copper tubes for use in treating molten copper and copper-base alloys. Shot is sold in 1.19—4.76 mm (16—4 mesh) sizes. Lithium dispersions (30% in mineral oil) of 10—50-p.m particle size are used primarily in organic chemical reactions. Dispersions in other solvents and of other size fractions can be suppHed. 

The molten carbonate fuel ceU uses eutectic blends of Hthium and potassium carbonates as the electrolyte. A special grade of Hthium carbonate is used in treatment of affective mental (mood) disorders, including clinical depression and bipolar disorders. Lithium has also been evaluated in treatment of schizophrenia, schizoaffective disorders, alcoholism, and periodic aggressive behavior (56). 

Lithium ion is commonly ingested at dosages of 0.5 g/d of lithium carbonate for treatment of bipolar disorders. However, ingestion of higher concentrations (5 g/d of LiCl) can be fatal. As of this writing, lithium ion has not been related to industrial disease. However, lithium hydroxide, either dHectly or formed by hydrolysis of other salts, can cause caustic bums, and skin contact with lithium haHdes can result in skin dehydration. Organolithium compounds are often pyrophoric and requHe special handling (53). 

Resoles are usually those phenolics made under alkaline conditions with an excess of aldehyde. The name denotes a phenol alcohol, which is the dominant species in most resoles. The most common catalyst is sodium hydroxide, though lithium, potassium, magnesium, calcium, strontium, and barium hydroxides or oxides are also frequently used. Amine catalysis is also common. Occasionally, a Lewis acid salt, such as zinc acetate or tin chloride will be used to achieve some special property. Due to inclusion of excess aldehyde, resoles are capable of curing without addition of methylene donors. Although cure accelerators are available, it is common to cure resoles by application of heat alone. 

This reaction does not need any special handling and the reduction conditions commonly used witli lithium aluminum hydride (see chapter 2) are equally applicable with lithium aluminum deuteride. 

The bromination of 4,5-j -dihydrocortisone acetate in buffered acetic acid does not proceed very cleanly (<70%) and, in an attempt to improve this step in the cortisone synthesis, Holysz ° investigated the use of dimethylformamide (DMF) as a solvent for bromination. Improved yields were obtained (although in retrospect the homogeneity and structural assignments of some products seem questionable.) It was also observed that the combination of certain metal halides, particularly lithium chloride and bromide in hot DMF was specially effective in dehydrobromination of 4-bromodihydrocortisone acetate. Other amide solvents such as dimethylacetamide (DMA) and A-formylpiperidine can be used in place of DMF. It became apparent later that this method of dehydrobromination is also prone to produce isomeric unsaturated ketones. When applied to 2,4-dibromo-3-ketones, a substantial amount of the A -isomer is formed. 

A rather special procedure for the preparation of 21-hydroxy-20-ketopreg-nanes starts with the 17a-ethoxyethynyl-17 -hydroxy steroids described earlier. Free radical addition of ethanethiol to the triple bond, followed by acid-catalyzed hydrolysis and dehydration gives the 20-thioenol ether 21-aldehyde. This can be reduced with lithium aluminum hydride to the C-21 alcohol and then hydrolyzed to the C-20 ketone in the presence of mercuric chloride. The overall yield, without isolation of intermediates, is in the order of 50% ... 

The small size of lithium frequently confers special properties on its compounds and for this reason the element is sometimes termed anomalous . For example, it is miscible with Na only above 380° and is immiscible with molten K, Rb and Cs, whereas all other pairs of alkali metals are miscible with each other in all proportions. (The ternary alloy containing 12% Na, 47% K and 41% Cs has the lowest known mp, —78°C, of any metallic system.) Li shows many similarities to Mg. This so-called diagonal relationship stems from the similarity in ionic size of the two elements / (Li ) 76pm, / (Mg ) 72pm, compared with / (Na ) 102pm. Thus, as first noted by Arfvedson in establishing lithium as a new element, LiOH and LiiCOs are much less soluble than the corresponding... 

The poor efficiencies of coal-fired power plants in 1896 (2.6 percent on average compared with over forty percent one hundred years later) prompted W. W. Jacques to invent the high temperature (500°C to 600°C [900°F to 1100°F]) fuel cell, and then build a lOO-cell battery to produce electricity from coal combustion. The battery operated intermittently for six months, but with diminishing performance, the carbon dioxide generated and present in the air reacted with and consumed its molten potassium hydroxide electrolyte. In 1910, E. Bauer substituted molten salts (e.g., carbonates, silicates, and borates) and used molten silver as the oxygen electrode. Numerous molten salt batteiy systems have since evolved to handle peak loads in electric power plants, and for electric vehicle propulsion. Of particular note is the sodium and nickel chloride couple in a molten chloroalumi-nate salt electrolyte for electric vehicle propulsion. One special feature is the use of a semi-permeable aluminum oxide ceramic separator to prevent lithium ions from diffusing to the sodium electrode, but still allow the opposing flow of sodium ions. 

Refrigerant temperatures greater than 32°F suggest the steam jet or lithium bromide absorption system. Between 30°F and —40°F, the ammonia-water absorption or a mechanical compression system is indicated. At less than —40°F, a mechanical compression is used, except in special desiccant situations. The economics of temperature level selection will depend on utility (steam, power) costs at the point of installation and the type of pay-out required, because in some tonnage ranges, the various systems are competitive based on first costs. 

Removal of the carbonate ring from 7 (Scheme 1) and further functional group manipulations lead to allylic alcohol 8 which can be dissected, as shown, via a retro-Shapiro reaction to give vinyl-lithium 9 and aldehyde 10 as precursors. Vinyllithium 9 can be derived from sulfonyl hydrazone 11, which in turn can be traced back to unsaturated compounds 13 and 14 via a retro-Diels-Alder reaction. In keeping with the Diels-Alder theme, the cyclohexene aldehyde 10 can be traced to compounds 16 and 17 via sequential retrosynthetic manipulations which defined compounds 12 and 15 as possible key intermediates. In both Diels-Alder reactions, the regiochemical outcome is important, and special considerations had to be taken into account for the desired outcome to. prevail. These and other regio- and stereochemical issues will be discussed in more detail in the following section. 

For the preparation of samples for X-ray fluorescence spectroscopy, lithium metaborate is the preferred flux because lithium does not give rise to interfering X-ray emissions. The fusion may be carried out in platinum crucibles or in crucibles made from specially prepared graphite these graphite crucibles can also be used for the vacuum fusion of metal samples for the analysis of occluded gases. 

The quality and quantity of sites which are capable of reversible lithium accommodation depend in a complex manner on the crystallinity, the texture, the (mi-cro)structure, and the (micro)morphology of the carbonaceous host material [7, 19, 22, 40-57]. The type of carbon determines the current/potential characteristics of the electrochemical intercalation reaction and also potential side-reactions. Carbonaceous materials suitable for lithium intercalation are commercially available in many types and qualities [19, 43, 58-61], Many exotic carbons have been specially synthesized on a laboratory scale by pyrolysis of various precursors, e.g., carbons with a remarkably high lithium storage capacity (see Secs. 

---