Methyllithium
Synonym(s):Lithium methanide;MeLi
- CAS NO.:917-54-4
- Empirical Formula: CH3Li
- Molecular Weight: 21.98
- MDL number: MFCD00008253
- EINECS: 213-026-4
- SAFETY DATA SHEET (SDS)
- Update Date: 2023-08-17 13:06:49
What is Methyllithium?
Chemical properties
Methyllithium is a colorless to yellowish solution, It is insoluble in hydrocarbon solvents although propyllithium and the higher homologues are miscible in hydrocarbons. Methyllithium is soluble in diethyl ether to about 6% by weight at room temperature (with or without lithium bromide) and is a little less soluble in tetrahydrofuran. Cooling of these solutions produces clear, colorless crystals of methyllithium etherate. Methyllithium is stable to about 200°C, at which temperature it disproportionates to dilithiomethane and methane.
The Uses of Methyllithium
There are no significant industrial uses of methyllithium, but it is widely used in the laboratory in Grignard type reactions.
Methyllithium is an organolithium reagent mainly used for deprotonation and as a source of methyl anion. It is a strong base and a strong nucleophile.
The Uses of Methyllithium
Methyllithium lithium bromide complex solution (MeLi.LiBr) can be used as a methylating agent for the α-methylation of alkoxyaryl ketones.
Preparation
Methyllithium is produced industrially by the reaction of methyl chloride or methyl bromide with lithium metal dispersion in diethyl ether. The reaction with methyl chloride yields a solution of methyllithium and a precipitate of lithium chloride which may be readily separated. When methyl bromide is used, the lithium bromide byproduct remains in solution and complexes with the methyllithium. This reduces the reactivity of the methyllithium and, in certain cases, affects its usefulness. On the other hand, the less reactive complex is more stable in diethyl ether. Methyllithium produced from methyl chloride contains only about 0.3 % lithium chloride in a 5 % solution in diethyl ether. It is more reactive than the lithium bromide complex, but decomposes at the rate of 1 % of the contained methyllithium per year (that is 5.00 % solution goes to 4.95 %) at room temperature. The decomposition by ether cleavage results in methane and ethylene formation which increases the pressure in the container on long storage. Methyllithium can be prepared easily in tetrahydrofuran but it has a half-life of only about 2 days at room temperature due to solvent cleavage.
What are the applications of Application
Methyllithium solution (1.6M in diethyl ether) has been used for the asymmetric allylic alkylation (AAA) of allylic electrophiles in the presence of a chiral copper catalyst. This protocol leads to the C-C bond formation of tertiary and quaternary stereogenic centers with high enantioselectivity. It can also be used for the synthesis of (?)-salsolidine by reacting with 6,7-dimethoxy-3,4-dihydroisoquinoline in the presence of (?)-sparteine as a chiral ligand.
Definition
ChEBI: Methyllithium is an alkyllithium compound and a one-carbon compound.
Hazard
Flammable, dangerous fire and explosionrisk, self-ignites in air.
Properties of Methyllithium
Melting point: | 70-71℃ |
Boiling point: | 88℃ |
Density | 0.85 g/mL at 20 °C |
vapor density | 3 (vs air) |
Flash point: | 5 °F |
storage temp. | 2-8°C |
form | Solution |
Specific Gravity | 0.83 |
color | Colorless to yellow |
Water Solubility | Reacts with water. |
Sensitive | Air & Moisture Sensitive |
Hydrolytic Sensitivity | 9: reacts extremely rapidly with atmospheric moisture - may be pyrophoric - glove box or sealed system required |
BRN | 3587162 |
Exposure limits | ACGIH: TWA 400 ppm; STEL 500 ppm OSHA: TWA 400 ppm(1200 mg/m3) NIOSH: IDLH 1900 ppm |
CAS DataBase Reference | 917-54-4(CAS DataBase Reference) |
EPA Substance Registry System | Lithium, methyl- (917-54-4) |
Safety information for Methyllithium
Signal word | Danger |
Pictogram(s) |
Flame Flammables GHS02 Corrosion Corrosives GHS05 Skull and Crossbones Acute Toxicity GHS06 Exclamation Mark Irritant GHS07 Health Hazard GHS08 Environment GHS09 |
GHS Hazard Statements |
H225:Flammable liquids H250:Pyrophoric liquids; Pyrorophoric solids H252:Self-heating substances and mixtures H260:Substances And Mixtures Which, In Contact With Water,Emit Flammable Gases H302:Acute toxicity,oral H303:Acute toxicity,oral H304:Aspiration hazard H311:Acute toxicity,dermal H314:Skin corrosion/irritation H315:Skin corrosion/irritation H318:Serious eye damage/eye irritation H335:Specific target organ toxicity, single exposure;Respiratory tract irritation H336:Specific target organ toxicity,single exposure; Narcotic effects H401:Hazardous to the aquatic environment, acute hazard H411:Hazardous to the aquatic environment, long-term hazard |
Precautionary Statement Codes |
P210:Keep away from heat/sparks/open flames/hot surfaces. — No smoking. P222:Do not allow contact with air. P223:Keep away from any possible contact with water, because of violent reaction and possible flash fire. P261:Avoid breathing dust/fume/gas/mist/vapours/spray. P280:Wear protective gloves/protective clothing/eye protection/face protection. P231+P232:Handle under inert gas. Protect from moisture. P309:IF exposed or if you feel unwell: P310:Immediately call a POISON CENTER or doctor/physician. P303+P361+P353:IF ON SKIN (or hair): Remove/Take off Immediately all contaminated clothing. Rinse SKIN with water/shower. P305+P351+P338:IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continuerinsing. P370+P378:In case of fire: Use … for extinction. P405:Store locked up. P422:Store contents under … P402+P404:Store in a dry place. Store in a closed container. |
Computed Descriptors for Methyllithium
Abamectin manufacturer
Sanpra Synthesis Private Limited
JSK Chemicals
Ortin Laboratories Limited
Organo Metallics
HYCHEM LABORATORIES
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