lithium bromide[7], is a kind ofInorganic, molecular formula is LiBr[7], white cubic crystal system crystal or granular powder, extremely soluble in water, soluble inethanolandEther, slightly soluble in pyridine, soluble in methanol, acetone, ethylene glycol and other organic solvents.It is an efficient water vapor absorbent and air humidity regulator.It can be used as absorption refrigerant in organic chemistryHydrogen chlorideRemoverfibreFluffing agentHypnoticandsedativeIt is also used in photographic industry, analytical chemical reagent and someHigh energy batteryElectrolytes in.[1]
Chinese name
lithium bromide[2]
Foreign name
Lithium bromide[1]
chemical formula
LiBr[2]
molecular weight
eighty-six point eight five[2]
CAS login number
7550-35-8[2]
EINECS login number
231-439-8[2]
Water solubility
Extremely soluble in water, soluble inethanolandEther
Appearance
White cubic crystal system crystal or granular powder
Character is white cubeCrystal systemCrystalline or granular powder.Density 3.464g/cmthree, melting point 442-547 º C, boiling point 1265 º C.[2]Easily soluble in water, with a solubility of 254g/100ml water (90 ℃);Soluble in ethanol and ether;Slightly soluble inpyridine；Soluble inmethanol、acetone、glycolIsoorganicsolvent。[3]It has strong water absorption and is very soluble in water, and can form a series of hydrates: LiBr · HtwoO、LiBr·2HtwoO、LiBr·3HtwoO。It is dihydrate at normal temperature, which is white crystal. It loses 1 molecular crystal water at 44 ℃, and becomes anhydrous when it is higher than 160 ℃.Its aqueous solution is neutral or slightly alkaline.It is extremely corrosive to general metals.The main measures to prevent corrosion are first to maintain a high vacuum to isolate oxygen, and then to addCorrosion inhibitorAnd keep the solution temperature below 120 ℃.Hot concentrated solution can dissolvecellulose。Strengthen the heat in the air, significantly decompose, release bromine and generate a small amount of lithium carbonate and lithium oxide, which are alkaline.It can strongly corrode glass, porcelain and platinum when melting.LiBr · nNH is generated by reacting with gaseous ammoniathree。[3]
Calculate chemical data
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1. Reference value for drainage parameter calculation (XlogP): None[2]
11. Determine the number of atomic structure centers: 0[2]
12. Number of uncertain atomic structure centers: 0[2]
13. Determine the number of chemical bond structure centers: 0[2]
14. Number of uncertain chemical bond structure centers: 0[2]
15. Number of covalent bond units: 2[2]
Ecological data
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Generally, it is not harmful to water. Do not discharge materials into the surrounding environment without government permission.[2]
chemical property
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Stable in nature, not easy to deteriorate and decompose in the atmosphere.Can form a series ofAdditive compound, such as monoammonium lithium bromide, diammonium lithium bromide, triammonium lithium bromide, and tetraammonium lithium bromide.This product can also be used withBuli It forms a stable complex, which is very stable in ether, so it is often usedBromobutaneSynthesis of butyl lithium.At the same time, lithium bromide is also associated withCupric bromide, high mercury bromide, high mercury iodideHigh mercury cyanide、Strontium bromideIt can form soluble salt.Lithium bromide has a strong effect on steel in the airCorrosionHowever, corrosion inhibitor is added in vacuum state, which basically does not corrode metal.[4]
toxicity
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Large dose of lithium bromide will inhibitcentral nervous systemLong term inhalation may cause skin rash and central nervous system disorder.[5]
synthetic method
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1. Neutralization method
Lithium hydroxideAndHydrobromic acidconductNeutralization reactionThe reaction solution is decolorized, filtered, concentrated, filtered, concentrated, crystallized, and separated to produce lithium bromide granular powder.The reaction equation is as follows:[2]
LiOH + HBr = LiBr + HtwoO[2]
2. Ferric bromide process
Iron filings are reacted with bromine to form iron bromide, and lithium bromide is prepared by the reaction of lithium carbonate and iron bromide.This process is complicated and easy to cause loss of lithium bromide and reduce the yield.[2]
3. Dissolve pure lithium carbonate in hydrobromic acid solution, evaporate to dryness, and remove COtwoAnd water to obtain lithium bromide.[2]
If special pure lithium bromide is to be preparedcrystalRemove most impurities several times.The specific operation is as follows: hydrobromic acid is added to LiBr solution to precipitate lithium bromide.Inject nitrogen and heat the above solution andprecipitateTo remove excessacid。The precipitate is filtered out under nitrogen atmosphere.Recrystallization is carried out by using lithium bromide with large difference in solubility in water at different temperatures and repeated for 4-5 times.Finally, in a platinum container,nitrogenKeep at 160 ℃ for more than 7 days in the atmosphere, and seal such refined lithium bromide in glass tube for storage.[2]
4. First, prepare lithium carbonate into a 55% - 60% solution, then slowly add 45% hydrobromic acid with a slight excess under heating and constant stirring for reaction:[2]
LitwoCOthree+ 2HBr = 2LiBr + COtwo+ HtwoO[2]
After the reaction, filter out the insoluble matter, heat and concentrate the filtrate until a small amount of crystallization occurs, stop heating, cool and crystallize, after crystallization is complete, separate the mother liquor, dry and dehydrate to obtain the finished product.Mother liquor can be re concentrated and crystallized.[2]
application
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54%-55%lithium bromide It can be used as absorption refrigerant, large-scale refrigeration system, water vapor absorbent, air temperature regulator, absorption refrigerant, hydrogen chloride remover, desiccant, etc.[2]
It is also used in photographic industry, analytical chemistry and someHigh energy batteryElectrolytes andChemical Reagents。It can be used for photography and battery.[2]
Storage method
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1. It shall be stored in a ventilated and dry warehouse.[2]
2. The package shall be sealed and damp proof.Rain and sunlight shall be prevented during transportation.[2]
2. Lithium bromide in watersolubilityIt decreases with the decrease of temperature.[6]
3、steamThe partial pressure is very small.It is better than that of water at room temperatureSaturated vapor pressureIt is much smaller, has strong hygroscopicity, andLithium bromide aqueous solutionIt has the ability to absorb water vapor whose temperature is much lower than that of lithium bromideAbsorption refrigeratorOne of the mechanisms.[6]
4. The specific heat capacity is small.This means that the heat added to the solution during the occurrence is relatively small, and in addition, the evaporation latent heat of water is relatively large, which will make the unit have a higher thermal coefficient.[6]
5. The density is larger than water, the viscosity is larger, and the surface tension is larger.[6]
