Ethylene lithium complexes

An alternate ethynylating reagent is the lithium acetylide-ethylene-diamine complex which is available commercially. This reagent in dimethyl sulfoxide solution has been used to ethynylate 11 j -hydroxyestrone and its 3-methyl ether. 

An ethynylation reagent obtained by decomposition of lithium aluminum hydride in ethers saturated with acetylene gives a satisfactory yield of (64), Best results are obtained with the lithium acetylide-ethylene diamine complex in dioxane-ethylenediamine-dimethylacetamide. Ethynylation of (63) with lithium acetylide in pure ethylenediamine gives (64) in 95% yield. 

It is clear from these experiments that the presence of ethylene catalyses the fixation of nitrogen in lithium complexes. This assisted complexation was also observed with methyl-substituted ethylene and butadiene. It is a characteristic property of lithium-alkene complexes, as experiments performed with other lithium complexes have so far not yielded such ternary complexes. If one can easily anticipate that the fractional positive charge on the lithium in LiC2H4 and Li(C2H4)2 facilitates the coordination of N2 with, presumably, a a-donation to lithium, and possibly, to a weaker extent, p-donation from the metal, it is difficult to rationalize why LiC2H2 and LiC2H4 behave so differently with respect to nitrogen, for instance. 

Sodium acetylides are the most common reagents, but lithium, magnesium and other metallic acetylides have also been used. A particularly convenient reagent is lithium acetylide-ethylene diamine complex. Alternatively, the substrate may be treated with the alkyne itself in the presence of a base, so that the acetylide is generated in situ. 1,4-Diols can be prepared by treatment of aldehyde with dimetalloacetylenes. 

Longer-chain alkyl halides may not be commercially available, but they are readily made in one step from the corresponding alcohols (Larock, 1999), as are tosylates and mesylates. Similarly, longer-chain terminal alkynes are not commercially available, but can be readily made by reaction of alkyl halides with lithium acetylide-ethylene diamine complex in dry... 

An improved synthesis of 2 -azido-2 -deoxyuridine has been desoibed, in which 2,2-anhydrouridine is treated with tlw lithium azide-tetramelhyl ethylene diamine complex, generated in situ ... 

Tsuchida, E., Ohno, H., Tsunemi, K., and Kobayashi, N., Lithium ionic conductivities in poly(methacrylic acid)-poly(ethylene oxide) complex containing lithium perchlorate. Solid State Ionics, II, 227-233 (1983). 

Crassous, Abadie, and Schue have studied ethylene polymerizations where the initiator is n-butyl-lithium complexed with tetraethylethylenediamine (TEEDA). As with TMEDA, the addition of TEEDA to the reaction mixture caused an increase in rate to a limiting value. An interesting difference between the kinetic behaviour of the two bases is that the propagation is first order in TEEDA it was suggested that steric hindrance prevents the aggregation of TEEDA-complexed RLi into unreactive dimers. 

As a representative example, the solid state structure of the corresponding ethylene-bridged complex is shown in Scheme 2.2 and exhibits the special role of one lithium counter ion that stabilizes the helicate in concert with two molecules of water as a template. Later, bisimine-bridged ligands were also used to examine this class of coordination compounds. In this case, the helicates can be formed by simply mixing a diamine, 2,3-dihydroxybenzaldehyde, a source of titanium(IV) ions, and an alkali metal carbonate as a base. This procedure in principle resembles a hierarchical process with an initial imine condensation followed by helicate self-assembly, although the order of events cannot be predicted definitively. 

The polarity of the Li—C bond is so much increased by co-ordination with TMED that the TMED n-butyl-lithium complex adds ethylene under moderate pressure giving polymers. Reaction in the presence of benzene gives phenyl-ended telomers ... 

The initial trigger for studying this was that Kato and Ohno were members of the Polymer Nano Organization, a Scientific Research Priority Research of MEXT that was headed by Prof. Toyoki Kunitake from 1996 to 1998. At that time, Kato had built various supramolecular hydrogen-bonded liquid crystals [150-152]. Among them was one that had an oxyethylene chain [153], In the past, Ohno had studied polymer electrolyte, poly (ethylene oxide), complexed with lithium salts. The combination of these two concepts, i.e., lithium salt liquid crystals having oxyethylene chains, should lead to liquid electrolytes having ion channels that anisotropically carry ions. 

Simplest examples are prepared by the cyclic oligomerization of ethylene oxide. They act as complexing agents which solubilize alkali metal ions in non-polar solvents, complex alkaline earth cations, transition metal cations and ammonium cations, e.g. 12—crown —4 is specific for the lithium cation. Used in phase-transfer chemistry. ... 

Poly(ethylene oxide) associates in solution with certain electrolytes (48—52). For example, high molecular weight species of poly(ethylene oxide) readily dissolve in methanol that contains 0.5 wt % KI, although the resin does not remain in methanol solution at room temperature. This salting-in effect has been attributed to ion binding, which prevents coagulation in the nonsolvent. Complexes with electrolytes, in particular lithium salts, have received widespread attention on account of the potential for using these materials in a polymeric battery. The performance of soHd electrolytes based on poly(ethylene oxide) in terms of ion transport and conductivity has been discussed (53—58). The use of complexes of poly(ethylene oxide) in analytical chemistry has also been reviewed (59). 

A second type of soHd ionic conductors based around polyether compounds such as poly(ethylene oxide) [25322-68-3] (PEO) has been discovered (24) and characterized. These materials foUow equations 23—31 as opposed to the electronically conducting polyacetylene [26571-64-2] and polyaniline type materials. The polyethers can complex and stabilize lithium ions in organic media. They also dissolve salts such as LiClO to produce conducting soHd solutions. The use of these materials in rechargeable lithium batteries has been proposed (25). 

A second class of important electrolytes for rechargeable lithium batteries are soHd electrolytes. Of particular importance is the class known as soHd polymer electrolytes (SPEs). SPEs are polymers capable of forming complexes with lithium salts to yield ionic conductivity. The best known of the SPEs are the lithium salt complexes of poly(ethylene oxide) [25322-68-3] (PEO), —(CH2CH20) —, and poly(propylene oxide) [25322-69-4] (PPO) (11—13). Whereas a number of experimental battery systems have been constmcted using PEO and PPO electrolytes, these systems have not exhibited suitable conductivities at or near room temperature. Advances in the 1980s included a new class of SPE based on polyphosphazene complexes suggesting that room temperature SPE batteries may be achievable (14,15). 

Some instances of incomplete debromination of 5,6-dibromo compounds may be due to the presence of 5j5,6a-isomer of wrong stereochemistry for anti-coplanar elimination. The higher temperature afforded by replacing acetone with refluxing cyclohexanone has proved advantageous in some cases. There is evidence that both the zinc and lithium aluminum hydride reductions of vicinal dihalides also proceed faster with diaxial isomers (ref. 266, cf. ref. 215, p. 136, ref. 265). The chromous reduction of vicinal dihalides appears to involve free radical intermediates produced by one electron transfer, and is not stereospecific but favors tra 5-elimination in the case of vic-di-bromides. Chromous ion complexed with ethylene diamine is more reactive than the uncomplexed ion in reduction of -substituted halides and epoxides to olefins. ... 

A rather complex fused isoindoline (87) has been found to show good anorectic activity. This substance differs from other anorectic agents by not being a p-phenethylamine analogue. Preparation of this compound starts by reaction of a substituted benzoyl-benzoic acid (82) with ethylene diamine. The product (84) can be rationalized as being the aminal from the initially obtained monoamide 83. This is then subjected to reduction with lithium aluminum hydride... 

Lithium polymer electrolytes formed by dissolving a lithium salt LiX (where X is preferably a large soft anion) in poly(ethylene oxide) PEO can find useful application as separators in lithium rechargeable polymer batteries.Thin films must be used due to the relatively high ionic resistivity of these polymers. For example, the lithium-ion conductivity of PEO—Li salt complexes at 100 °C is still only about Viooth the conductivity of a typical aqueous solution. 

A new development in silsesquioxane ehemistry is the eombination of sil-sesquioxanes with cyclopentadienyl-type ligands. Reeently, several synthetie routes leading to silsesquioxane-tethered fluorene ligands have been developed. The scenario is illustrated in Seheme 47. A straightforward aeeess to the new ligand 140 involves the 1 1 reaction of 2 with 9-triethoxysilylmethylfluorene. Alternatively, the chloromethyl-substituted c/oxo-silsesquioxane derivative 141 can be prepared first and treated subsequently with lithium fluorenide to afford 140. Compound 141 has been used as starting material for the preparation of the trimethylsilyl and tri-methylstannyl derivatives 142 and 143, respeetively, as well as the novel zirconoeene complex 144. When activated with MAO (methylalumoxane), 144 yields an active ethylene polymerization system. 

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