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HomeProduct name listMethyllithium

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
Methyllithium Structural

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.
Methyllithium

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)
ghs
Flame
Flammables
GHS02
ghs
Corrosion
Corrosives
GHS05
ghs
Skull and Crossbones
Acute Toxicity
GHS06
ghs
Exclamation Mark
Irritant
GHS07
ghs
Health Hazard
GHS08
ghs
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

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