Lithium salts reactions with

Although ethereal solutions of methyl lithium may be prepared by the reaction of lithium wire with either methyl iodide or methyl bromide in ether solution, the molar equivalent of lithium iodide or lithium bromide formed in these reactions remains in solution and forms, in part, a complex with the methyllithium. Certain of the ethereal solutions of methyl 1ithium currently marketed by several suppliers including Alfa Products, Morton/Thiokol, Inc., Aldrich Chemical Company, and Lithium Corporation of America, Inc., have been prepared from methyl bromide and contain a full molar equivalent of lithium bromide. In several applications such as the use of methyllithium to prepare lithium dimethyl cuprate or the use of methyllithium in 1,2-dimethyoxyethane to prepare lithium enolates from enol acetates or triraethyl silyl enol ethers, the presence of this lithium salt interferes with the titration and use of methyllithium. There is also evidence which indicates that the stereochemistry observed during addition of methyllithium to carbonyl compounds may be influenced significantly by the presence of a lithium salt in the reaction solution. For these reasons it is often desirable to have ethereal solutions... 

Some reports on the synthesis of [2.2.3]cyclazines seem to be worthy of note. A 10% yield of 2,3-diaza[2.2.3]cyclazine (242) was formed in the reaction of the lithium salt (241) with benzonitrile. The 3,5-bis(dehydro-2-azaindolizine) (243) has been discussed as an intermediate (80TL4193). 

A unique approach in nonaqueous electrochemistry which may be applicable to several fields, especially for batteries, was recently presented by Koch et al. (private communication). They showed that it is possible to use solid matrices based on lithium salts contaminated with organic solvents as electrolyte systems. These systems demonstrate several advantages over liquid systems based on the same solvents and salts as solutions. Their electrochemical windows are larger, especially in the anodic direction (oxidation reactions), and it appears that their reactivity toward active electrodes (e.g., Li, Li—C) is much lower than that of the liquid electrolyte systems. 

Synthesis.— The condensation of acetonitrile with ethyl thionoformate by means of butyl-lithium has been reported to yield thioformylacetonitrile (1) after subsequent treatment of the intermediate lithium salt (2) with hydrochloric acid. The thioaldehyde could not be isolated, but it was reasonably stable in solution in the tautomeric enethiol form (3), and was characterized as its stable S-methyl derivative (4). Several new, stable thioaldehydes, (5) and (6), have been synthesized by solvolysis of the VUsmeier salts (7) and (8) with aqueous sodium hydrogen sulphide. Some deuteriated analogues of (6) were similarly prepared from the corresponding salts (9). The thioaldehydes (10) were isolated as amorphous solids from the cycloaddition reaction of l,2-dithiole-3-thione with propiolic acid or its... 

Below -30°C salts precipitate from the solution and the reaction stops, probably because the pieces of lithium are covered with salt, [f the temperature is increased, the salts dissolve and the gloss on the lithium re-appears. 

C. The mixture was cooled to -70°C and the allene (0.22 mol) was added in 5-10 min while maintaining the temperature between -60 and -70°C. After stirring for an additional 30 min at -60°C the solution was ready for further conversions. In the raetallation with ethyllithium the salts initially present had disappeared almost completely after this period. During the lithiation with commercial butyl-lithium the reaction mixture was continuously homogeneous. The solution of the lithiated allenes should be kept below -60°C and used within a few hours. 

Stereoselectivities of 99% are also obtained by Mukaiyama type aldol reactions (cf. p. 58) of the titanium enolate of Masamune s chired a-silyloxy ketone with aldehydes. An excess of titanium reagent (s 2 mol) must be used to prevent interference by the lithium salt formed, when the titanium enolate is generated via the lithium enolate (C. Siegel, 1989). The mechanism and the stereochemistry are the same as with the boron enolate. 

Manufacture. Lithium fluoride is manufactured by the reaction of lithium carbonate or lithium hydroxide with dilute hydrofluoric acid. If the lithium carbonate is converted to the soluble bicarbonate, insolubles can be removed by filtration and a purer lithium fluoride can be made on addition of hydrofluoric acid (12). High purity material can also be made from other soluble lithium salts such as the chloride or nitrate with hydrofluoric acid or ammonium bifluoride (13). 

The metallic salts of trifluoromethanesulfonic acid can be prepared by reaction of the acid with the corresponding hydroxide or carbonate or by reaction of sulfonyl fluoride with the corresponding hydroxide. The salts are hydroscopic but can be dehydrated at 100°C under vacuum. The sodium salt has a melting point of 248°C and decomposes at 425°C. The lithium salt of trifluoromethanesulfonic acid [33454-82-9] CF SO Li, commonly called lithium triflate, is used as a battery electrolyte in primary lithium batteries because solutions of it exhibit high electrical conductivity, and because of the compound s low toxicity and excellent chemical stabiUty. It melts at 423°C and decomposes at 430°C. It is quite soluble in polar organic solvents and water. Table 2 shows the electrical conductivities of lithium triflate in comparison with other lithium electrolytes which are much more toxic (24). 

Reactions of the Hydroxyl Group. The hydroxyl proton of hydroxybenzaldehydes is acidic and reacts with alkahes to form salts. The lithium, sodium, potassium, and copper salts of sahcylaldehyde exist as chelates. The cobalt salt is the most simple oxygen-carrying synthetic chelate compound (33). The stabiUty constants of numerous sahcylaldehyde—metal ion coordination compounds have been measured (34). Both sahcylaldehyde and 4-hydroxybenzaldehyde are readily converted to the corresponding anisaldehyde by reaction with a methyl hahde, methyl sulfate (35—37), or methyl carbonate (38). The reaction shown produces -anisaldehyde [123-11-5] in 93.3% yield. Other ethers can also be made by the use of the appropriate reagent. 

Reaction with Carbon Nucleophiles. Unactivated a2iddines react with the lithium salts of malonates or p-keto esters in the presence of lithium salts to yield 3-substituted pyttohdinones (56—59), where R = alkyl and aryl, and R = alkoxyl, alkyl, and aryl. 

A novel method for preparing amino heterocycles is illustrated by the preparation of 2-amino-5-methylthiophene (159). In this approach vinyl azides act as NH2 equivalents in reaction with aromatic or heteroaromatic lithium derivatives (82TL699). A further variant for the preparation of amino heterocycles is by azide reduction the latter compounds are obtained by reaction of lithio derivatives with p- toluenesulfonyl azide and decomposition of the resulting lithium salt with tetrasodium pyrophosphate (Scheme 66) (82JOC3177). 

The methylhydrazone of acetophenone (112) underwent ready reaction with n-butyl-lithium giving the dianion (113) reaction with acid derivatives such acid chlorides or esters resulted in pyrazole (114) formation whereas with aldehydes, pyrazolines were obtained (76SC5). With dichloromethyleneiminium salts (115), 5-dimethylaminopyrazoles... 

---