Shaanxi BLOOM Tech Co., Ltd. is one of the most experienced manufacturers and suppliers of lithium aluminum hydride solution cas 16853-85-3 in China. Welcome to wholesale bulk high quality lithium aluminum hydride solution cas 16853-85-3 for sale here from our factory. Good service and reasonable price are available.
The chemical formula of Lithium Aluminum Hydride Solution (LAH) is LiAlH ₄, which is an inorganic compound composed of lithium (Li), aluminum (Al), and hydrogen (H). In its structure, aluminum atoms are surrounded by four hydrogen atoms, forming a tetrahedral configuration, while lithium ions are bound to [AlH ₄] ⁻ anions through ionic bonds. This unique structure endows LAH with extremely high reactivity.
It exhibits good solubility in polar non proton solvents, which is due to the interaction ability between solvent molecules and LAH. Polar non proton solvents stabilize LAH ion pairs through solvation, thereby promoting dissolution. This solution can reduce esters, carboxylic acids, acyl chlorides, aldehydes, ketones, etc. to their corresponding alcohols. For example, ethyl acetate is reduced to ethanol in LAH/THF solution. Nitro compounds, nitriles, and amides can be reduced to amines. For example, nitrobenzene is reduced to aniline. Under specific conditions, LAH can selectively reduce certain functional groups without affecting other parts.
|
We can ship under the real name! Lithium Aluminum Hydride, CAS 16853-85-3 HS code: 2850009090
Explanation for the real name shipping: |
 |
|
Chemical Formula |
AlH4Li |
|
Exact Mass |
38 |
|
Molecular Weight |
38 |
|
m/z |
38 (100.0%), 37 (8.2%) |
|
Elemental Analysis |
Al, 71.09; H, 10.62; Li, 18.29 |
|
|
|
Lithium Aluminum Hydride Solution (LiAlH ₄) is a highly effective reducing agent in organic synthesis, and its preparation requires strict adherence to key principles such as inert environment, low temperature control, and solvent selection.
Chemical Essence and Fundamental Properties
Molecular Structure and Reaction Activity
LiAlH ₄ is composed of lithium ions (Li ⁺) and tetrahedral [AlH ₄] ⁻ anions. Aluminum atoms are covalently bonded to four hydrogen atoms to form a high-energy hydrogen carrier. Its strong reducibility originates from the polarity of aluminum hydrogen bonds (with a electronegativity difference of Δ χ=1.5), which allows hydrogen atoms to carry some negative charges and easily attack positively charged centers such as carbonyl carbons. Experiments have shown that LiAlH ₄ has a reduction efficiency of over 98% for esters, carboxylic acids, and acyl chlorides, which is much higher than that of sodium borohydride (NaBH ₄) isothermal and reducing agents.
Physical state and solubility
Pure LiAlH ₄ is a white crystalline powder, while commercial products appear gray due to the presence of trace amounts of elemental aluminum (0.5% -2%). Its density is 0.917 g/cm ³ and its melting point is 190 ° C (before decomposition). The solubility data is as follows:
Ether: 25-30 g/100g (25 ° C), optimal solvent
Tetrahydrofuran (THF): 13 g/100g, commonly used in industry
Dimethoxyethane (DME): partially dissolved (5-8 g/100g)
Dioxane: Almost insoluble (0.1 g/100g)
The solvent polarity (ε) and electron donating ability (DN) are key factors affecting solubility. Ether (ε=4.3, DN=20.0) forms coordination bonds with Li ⁺ through lone pair electrons of oxygen atoms, stabilizing ion pairs; However, the solubility of dioxane (ε=2.2, DN=15.1) is significantly reduced due to insufficient polarity.
Solution preparation technology
Classical chemical synthesis method
Lithium hydride aluminum chloride route
Reaction equation: 4LiH+AlCl3 → (C ₂ H ₅) ₂ O → LiAlH ₄+3LiCl
Operation steps:
Pre treatment: Under nitrogen protection, vacuum dry lithium hydride (LiH) powder at 120 ° C for 2 hours to remove surface adsorbed water.
Solvent selection: Use anhydrous ether (moisture<50 ppm) as the reaction medium, with a boiling point (34.6 ° C) that facilitates subsequent distillation recovery.
Reaction control: Slowly add AlCl3 to the LiH suspension and maintain the temperature at -10 ° C to 0 ° C. The exothermic reaction needs to be controlled by an ice salt bath.
Post treatment: Filter to remove LiCl precipitate, concentrate the filtrate to a LiAlH ₄ concentration of 2M, and store in a polyethylene bottle.
Yield optimization: By adding 0.5% tetraisopropyl titanate (Ti (OiPr) ₄) as a catalyst, the yield can be increased from 82% to 91%.
Classical chemical synthesis method
Sodium aluminum displacement method (industrial grade)
Reaction pathway:
Na + Al + 2H₂ →(500°C, 100 atm)→ NaAlH₄
NaAlH₄ + LiCl → THF→ LiAlH₄ + NaCl
Process characteristics:
The high-pressure hydrogenation reaction needs to be carried out in a titanium alloy reaction vessel, with a temperature control accuracy of ± 2 ° C.
The salt displacement reaction requires the use of anhydrous THF (moisture<10 ppm) and the separation of NaCl through fractional crystallization.
The purity of industrial grade products can reach 99.5%, but the cost is 30% higher than that of chemical synthesis methods.
New catalytic routes
Naphthalene lithium titanium tetrachloride system
Reaction mechanism:
3.5g Li+32g naphthalene+0.45ml TiCl ₄ → (H ₂, 1 atm) → LiH · Ti composite
LiH·Ti + AlCl₃ →(C₂H₅)₂O→ LiAlH₄
Advantage:
The reaction temperature drops to room temperature (25 ° C), reducing energy consumption by 60%.
The titanium catalyst shortened the reaction time from 24 hours to 8 hours.
The titanium impurity in the product is less than 0.1%, and no additional purification is required.
Mechanochemical synthesis: LiH was directly reacted with AlCl3 in the solid state by high-energy ball milling (500 rpm, 2 hours), with a yield of 78%. This method is suitable for solvent-free conditions, but it needs to solve the problem of wear and contamination of ball milling tank materials (such as polytetrafluoroethylene).
Solution stability and degradation mechanism
Thermal decomposition kinetics
Lithium Aluminum Hydride Solution slowly decomposes into Li3AlH ₆ and LiH at room temperature, with a reaction order of 1.5 and an activation energy of Ea=102 kJ/mol. Transition metal impurities such as titanium and iron can increase the decomposition rate by 5 times, so high-purity raw materials (Fe<1 ppm, Ti<0.5 ppm) need to be used.
Solvent effect
Ether system: At -20 ° C, the half-life of LiAlH ₄ solution is 30 days; When heated to 25 ° C, the half-life is shortened to 7 days.
THF system: Due to the stronger coordination bond formed between the oxygen atom of THF and Li ⁺, the stability of the solution is improved, and the half-life at 25 ° C reaches 14 days.
Degradation Product Analysis
Through X-ray diffraction (XRD) and nuclear magnetic resonance (NMR) detection, the degradation products include:
Li3 AlH ₆ (hexagonal crystal system, hydrogen density reduced by 30%)
Al (OH)3 (generated when the solution is exposed to humidity>10%)
Li ₂ O (detected after long-term storage)
Synthesis of pharmaceutical intermediates: the core reducing reagent for high-end drugs
LAH solution is widely used in the synthesis of high-end drug intermediates such as anti-tumor, cardiovascular, neurological, anti-inflammatory, antiviral, etc. due to its strong reduction selectivity, few side reactions, and high purity. It is the gold standard for pharmaceutical grade reduction reagents.
Intermediate of paclitaxel: side chain reduction
Paclitaxel (a star anti-cancer drug) contains ester and amide groups in its side chain. It needs to be reduced at low temperature using LAH/THF to convert ester to alcohol, amide to amine, with a yield of 92% and an optical purity of 99%. This is a key step in the semi synthesis of paclitaxel.
Intermediate of imatinib: nitrile → primary amine
In the synthesis of imatinib (Gleevec, an anti leukemia drug), benzonitrile derivatives are reduced to primary amines by LAH with a yield of 95% and no impurities. Subsequently, they are condensed with acyl chlorides to form the target intermediate.
Intermediate of doxorubicin: carbonyl reduction
Doxorubicin (anthracycline anticancer drug) contains multiple ketone and ester groups, and requires LAH low-temperature selective reduction of the ketone group to a secondary alcohol while retaining the ester group. The regioselectivity is 98% to avoid excessive reduction and deactivation.
Atorvastatin intermediate: ester → diol
In the synthesis of atorvastatin (a lipid-lowering drug), long-chain diesters are reduced to 1,3-diol by LAH/THF reflux with a yield of 90% and chiral purity of 99.5%, which is a common key technology of statin drugs.
Intermediate of clopidogrel: amide → tertiary amine
Clopidogrel (antiplatelet drug) contains tertiary amides, which are reduced to tertiary amines by LAH with a yield of 93% and no secondary amine impurities. Subsequently, cyclization generates the thienopyridine core structure.
Fluoxetine intermediate: ketone → secondary alcohol
In the synthesis of fluoxetine (a antidepressant drug), acetophenone derivatives are reduced by LAH to chiral secondary alcohols with a yield of 94% and an ee value of 98%, making it a classic case of chiral drug synthesis.
Gabapentin intermediate: nitrile → primary amine
In the synthesis of gabapentin (an antiepileptic drug), cyclohexylnitrile is reduced by LAH to cyclohexylmethylamine with a yield of 92% and a purity of 99%. It is then condensed with acetic acid to produce the target drug.
Ibuprofen intermediate: carboxylic acid → alcohol
In the synthesis of ibuprofen (a nonsteroidal anti-inflammatory drug), isobutyl benzoic acid is reduced to isobutyl benzyl alcohol via LAH with a yield of 90%, followed by oxidation and acylation to produce ibuprofen.
Intermediate of oseltamivir: ester → alcohol
In the synthesis of oseltamivir (Tamiflu, an anti influenza drug), the multi substituted cyclohexene ester is selectively reduced to alcohol by LAH, with a yield of 91% and a stereoselectivity of 97%, which is a key step in the total synthesis.
Safety operation standards
Personal Protective Equipment (PPE)
+
-
Respiratory protection: NIOSH certified air supplied respirator (APF=1000) equipped with organic vapor filter canister.
Skin protection: Butyl rubber gloves (thickness 0.7mm, penetration time>480 minutes), chemical resistant clothing (Tychem 2000 material).
Eye protection: Full face mask (compliant with ANSI Z87.1 standard).
Operating Environment Control
+
-
Inert atmosphere: Protect with nitrogen (O ₂<1 ppm, H ₂ O<0.1 ppm) or argon (purity 99.999%).
Temperature monitoring: The reaction system is equipped with a platinum resistance thermometer (accuracy ± 0.1 ° C), which automatically triggers the cooling system when the temperature exceeds the limit.
Solvent purification: Use molecular sieve (4A type) and metallic sodium reflux treatment to reduce the moisture content of ether to below 10 ppm.
Emergency response to leakage
+
-
Isolation: Set a 10 meter radius warning zone and prohibit the use of electronic devices.
Neutralization: Cover the leaked material with dry sand (3 times the amount of leakage) to avoid direct contact.
Collection: Transfer the adsorbed substance to a polyethylene sealed bucket and label it as "corrosive hazardous waste".
Ventilation: Turn on the explosion-proof fan and continue to exhaust for 2 hours, monitoring the hydrogen concentration (<4% LEL).
Future research directions
Studying Lithium Aluminum Hydride Solution precursors released through light or heat control, such as cage like compounds triggered by ultraviolet light decomposition, can significantly reduce operational risks. Preliminary experiments have shown that the activity retention rate of such derivatives is>90% after 6 months of storage.
Exploring ionic liquids (such as [BMIM] [BF ₄]) as solvents for LiAlH ₄ solutions, their non flammability and high boiling point (>300 ° C) can improve safety. At present, the solubility of LiAlH ₄ in [BMIM] [BF ₄] is 5 g/100g (25 ° C), but the reaction rate is reduced by 40% compared to the ether system.
By using nanotechnology techniques such as preparing LiAlH ₄ particles with a wavelength of 20-50 nm, the reaction selectivity is improved and the generation of by-products is reduced. The experiment showed that the reduction yield of nitro compounds by nano LiAlH ₄ increased from 85% to 92%.
Frequently Asked Questions
What is the solvent for lithium aluminium hydride?
+
-
LiAlH4 is a stable crystalline solid, soluble in ether solvents in which it forms an aluminium complex (solubility Et2O 39g/100ml, THF 15g/100ml, THF/toluene (70/30) 17g/100ml) and able to reduce most polar functional groups (acids, amides, ester and nitriles).
How to make lithium aluminium hydride?
+
-
Lithium Aluminum Hydride (LiAlH4) For Reduction of Carboxylic ...Lithium aluminum hydride (
or LAH) is a powerful reducing agent in organic synthesis, typically used to reduce carbonyls (like carboxylic acids, esters, and ketones) into alcohols. It is prepared industrially by reacting lithium hydride and aluminum chloride, and it requires strictly anhydrous, inert conditions to prevent dangerous, exothermic reactions with moisture.
Hot Tags: lithium aluminum hydride solution cas 16853-85-3, suppliers, manufacturers, factory, wholesale, buy, price, bulk, for sale, hydrogen bromide solution, Barium Chloride Powder CAS 10361 37 2, 3 Acetylphenylboronic acid, Trypsin Powder CAS 9002 07 7, 6 Aminocaproic Acid CAS 60 32 2, Polymerization inhibitor 510 NPAL