Lithium chloride is an inorganic substance with the molecular formula of LiCl and molecular weight of 42.39.It's whitecrystal, deliquescence.Salty, soluble in water, ethanolacetone, pyridine and other organic solvents.It belongs to low toxicity, but has strong irritation and corrosion effects on eyes and mucous membranes.
Lithium chloride is a white crystal, easily soluble in water, with a solubility of 67g/100ml water under standard conditions.It is also soluble in ethanolacetone、pyridineetc.Organic solvent, but insoluble inEtherTherefore, if chlorine halogenated hydrocarbon is used to precipitate lithium chloride in ether during the preparation of alkyl lithium, free alkyl lithium reagent can be obtained（lithium bromide，Lithium iodideIt forms an adduct with alkyl lithium and acts as a stabilizer).[1]The melting point of lithium chloride is 605 ℃, the boiling point is 1350 ℃, and the lattice energy is 853 kJ/mol.
chemical property
The aqueous solution is neutral or slightly alkaline.electrolysisLithium chloride Metal lithium andchlorine。[2]Lithium metal can also be deposited from pyridine solution of anhydrous lithium chloride.[3]
Lithium chloride can form various hydrates from LiCl-HtwoThe phase diagram of O clearly shows that its hydrate has LiCl · HtwoO、LiCl·2HtwoO、LiCl·3HtwoO、LiCl·5HtwoO, etc.The amount of crystallization water depends on the crystallization temperature. The lower the temperature, the higher the degree of hydration.
Li can form coordination ion with ammonia [Li (NHthree)four]Therefore, the solubility of ammonia in lithium chloride solution is much higher than that in water.Like other ionic chlorides, lithium chloride can also provide chloride ion and lithium ion in aqueous solution, and precipitate insoluble chloride or lithium salt with some other ions, such as silver chloride:
LiCl + AgNOthree→ AgCl↓ + LiNOthree
Solubility
Lithium chloride isSodium chloride type structureThe chemical bond is not a typical ionic bond, so it can be dissolved in many organic solvents, and can form adducts with ethanol, methanol, and amines with different compositions.This property can be used to separate lithium chloride from alkali metal chloride.
Influenced by the smaller ion radius and higher hydration energy of lithium, the solubility of lithium chloride is much higher than that of other congener chlorides (83g/100mL, 20 ℃).Its aqueous solution is alkaline.
Lithium chloride solubility table (H2O)
0℃
10℃
20℃
30℃
40℃
50℃
60℃
70℃
80℃
90℃
100℃
69.2g
74.5g
83.5g
86.2g
89.8g
98.4g
112g
121g
128g
Preparation method
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Evaporate LiCl aqueous solution to obtain LiCl · 2HtwoO crystallization, anhydrous salt can be obtained when the temperature is higher than 98 ℃, but when heated until the crystallization water is completely removed, part of HCl will be hydrolyzed at the same time, making the product alkaline[3]。Pure anhydrous LiCl (pH of aqueous solution=6~7) needs to be dehydrated by decompressionfourCl co heating, heating to 200 ℃ in dry HCl airflow or drying with pure nitrogen spray under oxygen free conditions.LiCl·2HtwoO or anhydrous salt is easy to absorb moisture in the air and become water droplets.
In industry, it mainly consists oflithia mica、spodumeneAnd the salt brine after extracting NaCl and KCl.Usually, LitwoCOthreeOr LiOH and hydrochloric acid.Anhydrous LiCl produced by some reagent plants is often a block obtained by hot filtration when evaporating LiCl aqueous solution to 100-110 ℃, and its water content is 3% - 5%.The reaction equation is:
LitwoCOthree+ 2HCI → 2LiCl + HtwoO + COtwo↑[4]
Calculate chemical data
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1. Reference value for drainage parameter calculation (XlogP): None
PreparationLithium metalRaw materials.Flux (such as the production of titanium and aluminum) for electrolytic metal production, used as welding agent for aluminum, dehumidifying agent for air conditioners and special cement raw materials, as well as flame, and in battery industryLithium manganese batteryElectrolyte, etc.[6]Anhydrous LiCl is mainly used for electrolytic preparation of lithium and aluminumfluxandFluxAnd moisture absorption (dehumidification) agent in non freezing air conditioners.
Lithium metal can be prepared by electrolysis of LiCl/KCl mixed molten salt at 600 ℃.Lithium metal in industry is produced by this method.Lithium chloride is also used as a moisture remover in the air conditioning system, a good flux (such as the production of titanium and aluminum), a precipitator for RNA, and an additive in Still reaction when electrolyzing metals or preparing powders.
Lithium chloride can be mixed withN. N-Dimethylformamide(DMF) is prepared into solutions of different concentrations as solvents for dissolving polymers.It is commonly used as eluent for GPC to measure molecular weight.[7]
Security risk
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In the 1940s, lithium chloride was used as a substitute for table salt, but it was later found that lithium chloride was toxic to the body, so the application was stopped.Lithium salt will act oncentral nervous systemSimilar lithium carbonate is used to treat mental diseases.
