Lithium perchlorate solutions

Lithium perchlorate solutions are thermally unstable and show explosion risks, especially in ethers [50, 51],... 

A warning was given that the 5 molar solution in ether used as a solvent for Diels-Alder reactions would lead to explosions [1], Such a reaction of dimethyl acetylene-dicarboxylate and cyclooctatetraene in this solvent exploded very violently on heating. The cyclooctatetraene was blamed, with no supporting evidence [2]. It would appear desirable to find the detonability limits of any reaction mixture before any attempt is made to scale up. Initial studies have not shown detonability in any lithium perchlorate solution in an organic solvent, while adiabatic calorimetry showed exothermicity only above 150°C. Further testing is recommended [4]. A safe alternative to lithium perchlorate/ether as a solvent for Diels-Alder reactions is proposed [3]. 

Pistoia investigated the electroinitiated polymerisation of styrene in propylene carbonate-lithium perchlorate solutions at 25°C. Mechanistic evidence was obtained for the formation of perchloric acid at the anode and the cationic nature of the process thus proved. The kinetic analysis yielded a kp value of 0.5 M sec . Although no comparisons can be made between this result and previous ones in other solvents, the presence of lithium perchlorate was here a source of homocorgugation for the acid produced and thus the cause of considerable deactivation of its initiating power. As in previous cases, this was not recognised by the author. A simflar study by Pistoia and Scro-sati in dimethylsulphate gave an insoluble polymer at the anode and the nature or the initiator was not elucidated, but it did not seem to be perchloric acid. The cationic properties of this process was however proved... 

The cyclocondensation of x-aminoaldehydes 17 and 6 (see p 2931) with Danishefsky s diene 1 can be efficiently catalyzed by 0.5 M lithium perchlorate in diethyl ether with typical predominance of. jyM-pyrones 43 for monoprotected aldehydes and twm -pyrones 44 for Ar,N-diprotected7S. Similarly, diene 42 reacts with x-aminoaldehyde 17k to provide anti-AA, almost exclusively, when catalyzed by a 3.0 M lithium perchlorate solution. 

Grieco et al. and Ghosez et al. [25] have recently reported that lithium trifluorometha-nesulfonimide (LiNTf2) in acetone or diethyl ether is a safe alternative to lithium perchlorate solutions for effecting Diels-Alder and hetero-Diels-Alder reactions. In addition, the lithium salt of tetrakis(polyfluoroalkoxy)alu-minate (LiAl(OC(Ph)(CF3)2)4) was described, a new hydrocarbon-soluble catalyst, for carbon-carbon bond-forming reactions like the... 

Triethylsilane in 3M ethereal Lithium Perchlorate solution effects the reduction of secondary allylic alcohols and acetates (eq 18). The combination of triethylsilane and Titanium(IV) Chloride is a particularly effective reagent pair for the selective reduction of acetals. Treatment of ( )-frontalin with this pair gives an 82% yield of tetrahydropyran products with a cis. trans ratio of 99 1 (eq 19). This exactly complements the 1 99 product ratio of the same products obtained with Diisobutylaluminum Hydride. ... 

In the improvement of DNPDOH (2,2-dinitro-1,3-propanediol) [66], used sodium nitrite was reduced from 4 times to the equal amount, the amounts of sodium persulfate and potassium ferricyanide were adjusted, which reduced the impact of carbon emission pollution on the environment, and the cost of synthesis was reduced. The synthesis yield was 68 % after improvement, and lower than the production cost is much lower than that of silver nitration method. Major improvement in electrochemical synthesis of DNPOH is that In the first step, sodium hydroxide solution was added to an aqueous solution of 2-nitropropanol after 45 min of stirring at room temperature, lithium perchlorate solution and sodium nitrite solution were added to prepare the deprotonated 2-nitropropanol solution in the second step, deprotonated 2-nitro-propanol solution is added into the working electrode chamber and the reference electrode chamber of the electrolytic cell, and electrolytic reaction is continued for about 1 h under nitrogen for 20 min. Finally DNPOH will be obtained with a yield of about 40 %. The reaction mechanism is ... 

There is as yet no consolidated opinion as to the optimum electrolyte for lithium-sulfiir batteries. Experiments with solid polymer electrolyte are described, but aprotic electrolyte in a Celgard-type separator commonly used in lithium ion batteries is applied more frequently. A large number of electrolytes has been studied that differ both in solvents and the lithium salt. The greatest acceptance was gained by lithium imide solutions in dioxolane (or in a mixture of dioxolane and dimethoxyethane) and also lithium perchlorate solutions in sulfone. Dissolution of polysulfides in electrolyfe is accompanied by a noticeable increase in viscosity and specific resistance of electrolyte. It is the great complexity of the composition of the electrochemical system and that of the processes occurring therein that prevent as yet commercialization of lithium-sulfiir electrolytes. 

Depending on their specific compositions and the procedures by which they are produced, protein polymers may be soluble or insoluble in aqueous solution. The BetaSilk and ProNectin polymers are insoluble in water. Prom a lyophilized powder they can be dissolved in concentrated chaotropic solvents such as aqueous formic acid or lithium halide salt solutions. For example, SLP3 is soluble in 88% formic acid at 10 w t% or greater. If the formic acid is either diluted by addition of water or if its pH is neutralized, SLP3 will precipitate. SLPF is soluble in 4.5 M lithium perchlorate solution at 1 w t%. Once dissolved the solution can be diluted wadi water or phosphate buffer to 0.1 w t% or less. It will remain in solution temporarily depending on its concentration (O.OI wa% solution will precipitate in about 8 hours). 

Gnanaraj et al. (2003) measured both pressure and temperature rises during the decomposition reactions of electrolyte solutions for Li-ion batteries in a commercial ARC calorimeter in the temperature range 40-350 °C. Among other results, an explosion was observed with lithium perchlorate solution near 220 °C. 

Some workers have tried to correlate the Raman spectra of lithium perchlorate solutions with macroscopic (conductance and viscosity) measurements [229,230,237,238]. In 1,2-dimethoxyethane and 2-methoxyethanol, Raman spectroscopy shows that the solvation of the lithium ion is accomplished through the ethereal oxygen atom in both solvents and there is a good qualitative correlation between the degree of ionic pairing demonstrated by the conductance measurements and that revealed by the Vi(A,) envelope of the perchlorate anion. 

Figure 18.41 Molar conductivity of 1 molar lithium perchlorate solutions, in mixtures of (a) PC + DME and (b) PC + THE (From Matsuda in Ref. 1.)...

Splitting of waves which results in separation of a one-electron step has also been observed for aliphatic nitro compounds [28]. Thus, for example, a one-electron polarographic wave was observed for the potassium salt of dinitromethane in an unbuffered solution of lithium perchlorate (Fig. 2). To enable observation of a one-electron wave in solutions of nitroform it is sufficient to add 4% (by volume) of di-methylformamide or acetonitrile to its salt in lithium perchlorate solution as supporting electrolyte (Fig. 2). 

Fig. 2, Polarogtams fot potassium salts (5 10" mole /liter) of dinitiomethane (2) and nltrofcvm (3 and 4) with aqueous 0.1 N lithium perchlorate solution as suppcsting electrolyte. 3) With addition of di-methylfamamide 1) supporting electrol3rte.

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