Lithium Aluminium Hydride
Lithium Aluminium Hydride
CAS: 16853-85-3
Molecular Formula: LiAlH4
Lithium Aluminium Hydride - Names and Identifiers
Lithium Aluminium Hydride - Physico-chemical Properties
| Molecular Formula | LiAlH4 |
| Molar Mass | 37.954298 |
| Density | 0.97g/mLat 20°C |
| Melting Point | 125°C (dec.)(lit.) |
| Boling Point | 0°C |
| Flash Point | 99°F |
| Water Solubility | Reacts |
| Appearance | tablets (~0.5 g each) |
| Specific Gravity | 0.917 |
| Color | White to light gray |
| Odor | Odorless solid |
| Exposure Limit | TLV-TWA 2 mg(Al)/m3 (ACGIH). |
| Merck | 14,350 |
| Storage Condition | Store below +30°C. |
| Stability | Stable. Reacts violently with water, liberating hydrogen. Incompatible with strong oxidizing agents, alcohols, acids. |
| Sensitive | Air & Moisture Sensitive |
Lithium Aluminium Hydride - Risk and Safety
| Risk Codes | R15 - Contact with water liberates extremely flammable gases R34 - Causes burns R14/15 - R11 - Highly Flammable R36/37 - Irritating to eyes and respiratory system. R19 - May form explosive peroxides R40 - Limited evidence of a carcinogenic effect R10 - Flammable R67 - Vapors may cause drowsiness and dizziness R66 - Repeated exposure may cause skin dryness or cracking R22 - Harmful if swallowed R12 - Extremely Flammable R35 - Causes severe burns R37 - Irritating to the respiratory system R65 - Harmful: May cause lung damage if swallowed R48/20 - R63 - Possible risk of harm to the unborn child R36/38 - Irritating to eyes and skin. R61 - May cause harm to the unborn child R60 - May impair fertility |
| Safety Description | S43 - In case of fire use ... (there follows the type of fire-fighting equipment to be used.) S7/8 - S6A - S45 - In case of accident or if you feel unwell, seek medical advice immediately (show the label whenever possible.) S43B - S36/37/39 - Wear suitable protective clothing, gloves and eye/face protection. S33 - Take precautionary measures against static discharges. S26 - In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. S16 - Keep away from sources of ignition. S24/25 - Avoid contact with skin and eyes. S27 - Take off immediately all contaminated clothing. S29 - Do not empty into drains. S62 - If swallowed, do not induce vomitting; seek medical advice immediately and show this container or label. S53 - Avoid exposure - obtain special instructions before use. |
| UN IDs | UN 3399 4.3/PG 1 |
| WGK Germany | 2 |
| RTECS | BD0100000 |
| FLUKA BRAND F CODES | 10-21 |
| TSCA | Yes |
| HS Code | 2850 00 20 |
| Hazard Class | 4.3 |
| Packing Group | I |
| Toxicity | TLV-TWA (ACGIH) 2 mg (Al)/m3 |
Lithium Aluminium Hydride - Reference Information
| NIST chemical information | Information provided by: webbook.nist.gov (external link) |
| EPA chemical information | Information provided by: ofmpub.epa.gov (external link) |
| Introduction | Lithium aluminum hydride is a commonly used reducing reagent in organic chemistry, which can reduce a variety of functional group compounds; it can also act on double-bond and triple-bond compounds Realize the aluminum hydride reaction; lithium aluminum hydride can also participate in the reaction as a base. Lithium aluminum hydride has strong hydrogen transfer ability, which can reduce aldehydes, ketones, esters, lactones, carboxylic acids, acid anhydrides and epoxides to alcohols, or convert amides, imine ions, nitriles and aliphatic nitro compounds into corresponding amines. In addition, the super-strong reducing ability of lithium aluminum hydride makes it possible to act on other functional groups, such as reducing halogenated alkanes to alkanes. In this type of reaction, the activity of halogenates from large to small is iodinated, brominated and chlorinated. The solid and solution of lithium aluminum hydride are highly flammable and must be isolated from air and moisture, and it is best stored in a nitrogen atmosphere. |
| Physical and chemical properties | Lithium aluminum hydride has a 0.917 specific gravity, is stable in dry air, hydrolyzes in humid air and causes combustion. It can be dissolved in organic solvents such as ether and tetrahydrofuran. Aldehydes, ketones, acids, anhydrides, esters, quinones, acid chlorides, etc. can be reduced to alcohols, nitriles can be reduced to primary amines, and halogenated hydrocarbons can be reduced to hydrocarbons. But usually the carbon-carbon double bond cannot be hydrogenated. |
| application | lithium aluminum hydride is an inorganic metal compound, which is used as a reducing agent in medicine, perfume, pesticide, dye and other fine organic synthesis. |
| preparation | weigh 241.43g of aluminum chloride hexahydrate and 42.41g of lithium chloride, add water to dissolve, add a certain amount of sodium carbonate to dissolve liquid, after precipitation is complete, stand for suction filtration, after solid drying, calcination at 500-600 ℃ for 4 hours to obtain oxidized substance, and the oxide is in an autoclave, caH2 was added as catalyst, and solid hydrogenation was carried out at 180 ℃ and 20kg/cm2 hydrogen pressure for 4-5 hours to obtain aluminum-lithium mixed substance. Add catalyst naphthalene and TiCl4 to the organic solvent tetrahydrofuran, and pass hydrogen to hydrogenate for 4-5 hours at normal temperature and pressure to obtain lithium aluminum tetrahydride product. |
| quenching method | lithium aluminum hydride, the powder is very fine, wear a mask! Pay attention to the used weighing paper and steel spoon! At the end of the reaction, add solvent with methanol to destroy excessive lithium tetrahydroaluminum and wash with dilute hydrochloric acid, but emulsified, many flocculent solids are difficult to filter out with diatomite, and then washed with dilute sodium bicarbonate is also emulsified. 1. A better method is to quench with water at low temperature to generate colloidal particles, filter, and then wash with solvent several times, combine organic phases, wash, dry, and concentrate. 2. Quenching with water at low temperature, then adding a large amount of magnesium sulfate to form small particles, and filtering is much easier. If the reaction is small, you can try it. 3. After the reaction is completed, measure and add water, add magnesium sulfate to dry, and filter! 4. It is best to quench with NaOH solution, and then filter and desolam. It is assumed that the LiAlH4 dosage for the reaction is 1g. After the reaction is completed, cool the reaction mixture to -10~0 ℃, stir, and slowly add 1 mL of water to quench the reaction. After that, add 1 mL of 10% NaOH solution slowly. Filter out the resulting solid, wash it several times with a reaction solvent, and concentrate the filtrate under reduced pressure to obtain the product. If necessary, the solids can be soaked and washed with ethanol or methanol, concentrated and recovered more products (most of which contain inorganic salts at this time). Generally, the solid is suspended in the reaction solvent and is very easy to filter. Sometimes in the process of adding water, the reactants are relatively viscous, and some reaction solvents can be added to dilute them. Note: When adding water, the reaction is severe, a large amount of heat is released and gas is generated, so it must be added slowly. The order of water and NaOH should not be reversed, otherwise it may increase the adsorption of the product and affect the yield. |
| Use | Used as a reagent and reducing agent for the determination of carbonyl groups, and also used in the preparation of hydrides, silanes, boranes, etc. Used as a polymerization catalyst, reducing agent, jet engine fuel, and also used to synthesize drugs. Aldehydes, ketones, acids, anhydrides, esters, lactones, quinones, acid chlorides, etc. can be reduced to alcohols, nitriles can be reduced to primary amines, and halogenated hydrocarbons can be reduced to hydrocarbons. But usually the carbon-carbon double bond cannot be hydrogenated. Use: extremely strong reducing agent. Widely used in medicine, spices, pesticides and other fine organic synthesis. Lithium aluminum hydride is mainly used as a reducing agent in medicine, perfume, pesticide, dye and fine organic synthesis Used as a reducing agent in medicine, perfume, pesticide, dye and other fine organic synthesis |
| category | articles burning in contact with water |
| toxicity classification | poisoning |
| explosive hazard characteristics | blastable when mixed with oxidant |
| flammability hazard characteristics | high temperature, water, acid, oxidant release hydrogen combustible |
| storage and transportation characteristics | warehouse ventilation and low temperature drying; separate from oxidant and strong acid |
| fire extinguishing agent | dry powder, dry sand, stone powder |
| occupational standard | TWA 2 mg (AL)/m3 |
| toxic substance data | information provided by: pubchem.ncbi.nlm.nih.gov (external link) |
Last Update：2024-04-09 21:04:16
