917-54-4 Usage
Description
Methyllithium, an organolithium reagent, is a colorless to yellowish solution that is insoluble in hydrocarbon solvents but soluble in diethyl ether and tetrahydrofuran. It is a strong base and a strong nucleophile, mainly used for deprotonation and as a source of methyl anion. It is stable up to 200°C, at which temperature it disproportionates to dilithiomethane and methane.
Uses
Used in Laboratory Applications:
Methyllithium is widely used in the laboratory for Grignard type reactions, which are a class of chemical reactions that involve the formation of carbon-carbon bonds.
Used in Organic Synthesis:
Methyllithium is used as a methylating agent for the α-methylation of alkoxyaryl ketones, a process that involves the addition of a methyl group to the α-carbon of the ketone.
Used in Asymmetric Allylic Alkylation:
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.
Used in Pharmaceutical Synthesis:
Methyllithium can be used for the synthesis of complex organic compounds, such as (?)-salsolidine, by reacting with 6,7-dimethoxy-3,4-dihydroisoquinoline in the presence of (?)-sparteine as a chiral ligand. This application is particularly relevant in the pharmaceutical industry for the production of drugs with specific stereochemistry.
Although there are no significant industrial uses of methyllithium, its applications in laboratory settings and organic synthesis make it a valuable reagent in the field of chemistry.
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.
Hazard
Flammable, dangerous fire and explosionrisk, self-ignites in air.
Check Digit Verification of cas no
The CAS Registry Mumber 917-54-4 includes 6 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 3 digits, 9,1 and 7 respectively; the second part has 2 digits, 5 and 4 respectively.
Calculate Digit Verification of CAS Registry Number 917-54:
(5*9)+(4*1)+(3*7)+(2*5)+(1*4)=84
84 % 10 = 4
So 917-54-4 is a valid CAS Registry Number.
InChI:InChI=1/CH3.Li/h1H3;/rCH3Li/c1-2/h1H3
917-54-4Relevant articles and documents
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Mueller,Ludsteck
, (1955)
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Di- and Tri-valent Complexes of Ytterbium via Novel Metal Oxidation
Watson, Patricia L.
, p. 652 - 653 (1980)
Oxidation of Yb metal by iodopentamethylcyclopentadiene (IC5Me5) afforded Li and Li sequentially in the presence of LiI; analogous anionic chloride complexes, the new divalent complex Yb(C5Me5)2, and methyl derivatives of both d
Synthesis of 8-alkylthio- and 8-selanyl-3-tert-butylpyrazolo[5,1-c][1,2,4]triazines
Ivanov, Sergey M.,Minyaev, Mikhail E.,Mironovich, Lyudmila M.
, p. 666 - 676 (2020)
Interaction of 8-lithio-3-tert-butyl-4-oxopyrazolo[5,1-c][1,2,4]triazin-1-ide with elemental sulfur or selenium in THF with further in situ alkylation at –97 °C followed by warming to room temperature furnished a series of 3-tert-butyl-8-X-pyrazolo[5,1-c][1,2,4]triazin-4(6H)-ones (X = n-BuS, n-BuSe, MeSe, PhCH2S) in good yields. 8,8'-Diselanediylbis(3-tert-butylpyrazolo[5,1-c][1,2,4]triazin-4(1H)-one) was also isolated as a by-product in these reactions. One-pot interaction of the n-BuSe substituted derivative with diborane/boron trifluoride led to reduction of the 1,2,4-triazine core and partial elimination of the alkylselanyl moiety. The structures of the synthesized products were established on the basis of IR, 1H, 13C, 2D HMBC 1H–77Se NMR and high resolution mass spectra, as well as X-ray single crystal diffraction analyses. Two of the prepared compounds were also tested for antimicrobial and antifungal activities.
A new strategy for the synthesis of organosilicon compounds of cyclopropane derivatives
Gholizadeh, Saeed,Safa, Kazem D.,Pesyan, Nader Noroozi
, p. 245 - 251 (2020/11/10)
The one-pot reaction of tetra-substituted cyclopropyl benzyl bromide with tris(trimethylsilyl)methyllithium (TsiLi) and carbon disulfide resulted in 3-(4-((((trimethylsilyl)ethynyl)thio)methyl)phenyl)cyclopropane-1,1,2,2-tetracarbonitrile (3) and 3-(4-((trimethylsilyl)methyl)phenyl)cyclopropane-1,2-dicarbonitrile (4) in excellent yield. The reaction in the absence of carbon disulfide yielded 3-(4-(2,2,2-tris(trimethylsilyl)ethyl)phenyl)cyclopropane-1,1,2,2-tetracarbonitrile (5) in excellent yield at 08C to room temperature. All structures were characterised by IR, 1H NMR, and 13C NMR spectroscopies. The reaction mechanisms are discussed.
Functionalized α-bromocyclopropylmagnesium bromides: Generation and some reactions
Bolesov,Solov'eva,Baird
, p. 1580 - 1589 (2014/02/14)
Functional derivatives of gem-dibromocyclopropanes (ethers and esters of gemdibromocyclopropylmethanol, 2,2-dibromocyclopropanecarboxylic acids and their esters) undergo partial hydrodebromination at the treatment with isopropyl magnesium bromide (3-6 mol-equiv) in THF and then in methanol at -60°C affording the corresponding monobromides in 64-95% yields. The addition of nonsolvated magnesium bromide to the reaction mixture results in the considerable reduction of the amount of the Grignard reagent (from 6 to 3 mol-equiv). This allows achieving the partial hydrodebromination of 2,2-dibromocyclopropanecarboxylic acids. Pleiades Publishing, Ltd., 2013.
