• Nuclear Engineering and Technology
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• v.53 no.8
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• pp.2570-2575
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• 2021

The exchange behaviors of hydrogen isotopes between protonated lithium metal compounds and deuterated water or tritiated water were investigated. The various protonated lithium metal compounds were prepared by acid treatment of lithium metal compounds with different crystal structures and metal compositions. The protonated lithium metal compounds could more effectively reduce the deuterium concentration in water compared with the corresponding pristine lithium metal compounds. The H⁺ in the protonated lithium metal compounds was speculated to be more readily exchangeable with hydrons in the aqueous solution compared with Li⁺ in the pristine lithium metal compounds, and the exchanged heavier isotopes were speculated to be more stably retained in the crystal structure compared with the light protons. When the tritiated water (157.7 kBq/kg) was reacted with the protonated lithium metal compounds, the protonated lithium manganese nickel cobalt oxide was found to adsorb and retain twice as much tritium (163.9 Bq/g) as the protonated lithium manganese oxide (69.9 Bq/g) and the protonated lithium cobalt oxide (75.1 Bq/g) in the equilibrium state.

• Bulletin of the Korean Chemical Society
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• v.22 no.4
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• pp.367-371
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• 2001

Lithium inserted into artificial carbon has been synthesized as a function of the Li concentration. The characteristics of these prepared compounds were determined from the studies using X-ray diffraction(XRD), solid nuclear magnetic resonance (NM R) spectrophotometric and differential scanning calorimeter(DSC) analysis. X-ray diffraction showed that lower stage intercalation compounds were formed with increasing Li concentration. In the case of the AG3, most compounds formed were of the stage 1 structure. Pure stage 1 structural defects of artificial graphite were not observed. 7Li-NMR data showed that bands are shifted toward higher frequencies with increasing lithium concentration; this is because non-occupied electron shells of Li increased in charge carrier density. Line widths of the Li inserted carbon compounds decreased slowly because of nonhomogeneous local magnetic order and the random electron spin direction for located Li between graphene layers. The enthalpy and entropy changes of the compounds can be obtained from the differential scanning calorimetric analysis results. From these results, it was found that exothermic and endothermic reactions of lithium inserted into artificial carbon are related to the thermal stability of lithium between artificial carbon graphene layers.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.227-227
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• 2010

The intercalation chemistry of graphite presents an attractive route to obtain few-layered graphene platelets based on the expanded interlayer spacing. We report that the lithium can be intercalated into the graphite in a controllable manner by adjusting the variables such as temperature, pressure, and reaction time. From the X-ray diffraction experiments, the lithium-graphite intercalaltion compounds (Li-GICs) can be produced as the first stage compounds ($LiC_6$), the second-stage compounds ($LiC_{12}$), and the mixtures, which is most likely to be dependent on the temperature and reaction time. Since these Li-GICs are expected to facilitate the exfoliation of graphite, we investigated the feasibility of Li-GICs as a effective precursors for the generation of single-or few-layered graphite nano-platelets.

• Bulletin of the Korean Chemical Society
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• v.22 no.5
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• pp.481-487
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• 2001

Surface films formed prior to bulk reduction of lithium have been studied at gold, platinum, and copper electrodes in rigorously dried propylene carbonate solutions using electrochemical quartz crystal microbalance (EQCM) and secondary ion mass spectrometry experiments. The results indicate that the passive film formation takes place at a potential as positive as about 2.0 V vs. Li/Li+ , and the passive film thus formed in this potential region is thicker than a monolayer. Quantitative analysis of the EQCM results indicates that electrogenerated lithium reacts with solvent molecules to produce a passive film consisting of lithium carbonate and other compounds of larger molecular weights. The presence of lithium carbonate is verified by SIMS, whereas the lithium compounds of low molecular weights, including lithium hydroxide and oxide, are not detected. Further lithium reduction takes place underneath the passive film at potentials lower than 1.2 V with a voltammetric current peak at about 0.6 V.

• Journal of the Korean Chemical Society
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• v.22 no.4
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• pp.259-267
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• 1978

In order to find out the selective reducing characteristics of lithium borohydride, borane, and borane-lithium chloride (1 : 0.1) in the reduction of carbonyl compounds, five representative equimolar mixtures of carbonyl compounds were chosen; benzaldehyde-acetophenone, benzaldehyde-2-heptanone, 2-heptanone-benzophenone, acetophenone-benzophenone, and 2-heptanone-acetophenone, and reacted with limited amount of lithium borohydride, borane or borane-lithium chloride (1 : 0.1) in tetrahydrofuran (THF) at $0^{\circ}$. Borane-lithium chloride (1 : 0.1) showed the excellent selectivity, however, lithium borohydride and borane also exhibited good selectivity except for the 2-heptanone-acetophenone.

• Bulletin of the Korean Chemical Society
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• v.30 no.7
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• pp.1588-1592
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• 2009

Lithium cyanoaluminum hydride (LCAH) was prepared by the metal cation exchange reaction of sodium cyanoaluminum hydride with lithium chloride in tetrahydrofuran. The reducing characteristics of LCAH were explored systematically by the reaction with selected organic compounds containing representative functional groups under the standardized conditions (tetrahydrofuran, 0 ${^{\circ}C}$). The reducing ability of LCAH was also compared with of the sodium derivative, sodium cyanoaluminum hydride (SCAH). Generally, the reducing behavior of LCAH resembles that of SCAH closely, but the reactivity of LCAH toward representative organic functional groups appeared to be stronger than that of SCAH. Thus, the regent reduces carbonyl compounds, epoxides, amides, nitriles, disulfides, carboxylic acids and their acyl derivatives to the corresponding alcohols or amines, at a relatively faster rate than that of SCAH. The cyano substitution, a strong election-withdrawing group, diminishes the reducing power of the parent metal aluminum hydrides and hence effects the alteration of their reducing characteristics.

• Bulletin of the Korean Chemical Society
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• v.14 no.6
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• pp.743-749
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• 1993

The approximate rates and stoichiometry of the reaction of excess lithium tris(dihexylamino)aluminum hydride(LTDHA) with selected organic compounds containing representative functional groups under the standardized conditions (tetrahydrofuran, 0$^{\circ}$C) were studied in order to define the reducing characteristics of the reagent for selective reductions. The reducing ability of LTDHA was also compared with those of the parent lithium aluminum hydride(LAH), lithium tris(diethylamino)aluminum hydride(LTDEA), and lithium tris(dibutylamino)aluminum hydride(LTDBA). In general, the reactivity toward organic functionalities is in order of $LAH{\gg}LTDEA{\geq}LTDBA>LTDHA$. LTDHA shows a unique reducing characteristics. Thus, the reagent reduces aldehydes, ketones, esters, epoxides, and tertiary amides readily. Anthraquinone is cleanly reduced to 9,10-dihydro-9,10-anthracenediol without hydrogen evolution, whereas p-benzoquinone in inert to LTDHA. In addition to that, disulfides are also readily reduced to thiols without hydrogen evolution. However, carboxylic acids, anhydrides, nitriles, and primary amides are reduced slowly. Especially, this reagent reduces aromatic nitriles to the corresponding aldehydes in good yields.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.395-398
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• 1998

Lithium insertion has been studied in a number of vanadium oxides with special regard to their application as the active materials in rechargeable lithium cells. Very high stoichiometric energy densities for lithium insertion are found for several of these materials. Some vanadium oxides, e.g. V$_2$ $O_{5}$ and V$_{6}$ $O_{13}$, are now being used in commercially developed rechargeable Li batteries. Another material which is receiving remarkable attention for this kind of cells is LiV$_3$ $O_{8}$. In variety of ternary lithium-vanadium oxides, the lithium content can be varied between certain limits without major changes in the vanadium oxygen lattice. In our worts, the oxides which do net form these thermodynamically stable bronzes can still accommodate large amounts of lithium at ambient temperature, forming kinetically stable insertion compounds. These compounds owe their existence to the whereas lithium is easily introduced into these open structures. The oxides investigated are rather poor electronic conductors; the conductivity decrease with increase in the lithium content. Improvements in the electrode fabrication technique are needed to alleviate this Problem.oblem.

• Bulletin of the Korean Chemical Society
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• v.17 no.4
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• pp.380-384
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• 1996

Lithium trimethylalkynylaluminates, prepared conveniently by reacting trimethylaluminum with lithium alkynide, readily react with aldehydes and ketones to give the corresponding propargyl alcohols in 70-95% yields. The reaction is highly chemoselective; thus many other functional groups such as amides, nitriles, epoxides and halogen compounds are inert under the reaction conditions. The reagents also show an excellent 1,2-regiospecificity in the reactions with cyclic or acyclic α,β-unsaturated carbonyl compounds.

• Bulletin of the Korean Chemical Society
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• v.18 no.8
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• pp.890-895
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• 1997

The approximate rates and stoichiometry of the reaction of excess lithium tripiperidinoaluminum hydride (LTPDA), an alicyclic aminoaluminum hydride, with selected organic compounds containing representative functional groups under the standardized conditions (tetrahydrofuran, 25°) were examined in order to define the reducing characteristics of the reagent for selective reductions. The reducing ability of LTPDA was also compared with those of the parent lithium aluminum hydride (LAH) and lithium tris(diethylamino)aluminum hydride (LTDEA), a representative aliphatic aminoaluminum hydride. In general, the reactivity of LTPDA toward organic functionalities is weaker than LTDEA and much weaker than LAH. LTPDA shows a unique reducing characteristics. Thus, benzyl alcohol, phenol and thiols evolve a quantitative amount of hydrogen rapidly. The rate of hydrogen evolution of primary, secondary and tertiary alcohols is distinctive. LTPDA reduces aldehydes, ketones, esters, acid chlorides and epoxides readily to the corresponding alcohols. Quinones, such as p-benzoquinone and anthraquinone, are reduced to the corresponding diols without hydrogen evolution. Tertiary amides and nitriles are also reduced readily to the corresponding amines. The reagent reduces nitro compounds and azobenzene to the amine stages. Disulfides are reduced to thiols, and sulfoxides and sulfones are converted to sulfides. Additionally, the reagent appears to be a good partial reducing agent to convert primary carboxamides into the corresponding aldehydes.