Methyl lithium

Methyl lithium
IUPAC name Methyllithium Methyl lithium
Another name Lithium methanide リチウムメタニド
Identification information
CAS registration number	917-54-4
PubChem	2724049
ChemSpider	10254338
It is an address number on a day	J1.231I
EINECS	213-026-4
ChEBI	CHEBI: 51486
Beilstein	3587162
Cf. Gmelin	288
SMILES [Li]C
InChI InChI=1S/CH3.Li/h1H3; Key: DVSDBMFJEQPWNO-UHFFFAOYSA-N
Characteristic
Chemical formula	CH3Li
Molar mass	21.98 g mol-1
I can put a case, the data without the special mention for normal temperature (25 degrees Celsius), the ordinary pressure (100 kPa).

Methyl lithium (methyllithium) is an organolithium compound expressed in chemical formula CH₃Li. I sketch methyl radical with Me and am transcribed into MeLi. I form a meeting body (cluster) in out of the solution and solid state. Reactivity is very high and is used for organic composition as hydrocarbon solution and ether solution. Because I am poor at water and oxygen, it is necessary to handle it under an anhydrous anoxia condition. The normal is not prepared in a laboratory, and solution is commercially available widely.

Table of contents

Synthetic

I am composed by reacting bromomethane with metal lithium which made にけん out of diethyl ether turbid in the indicative mood.

${\displaystyle {\ce {2Li\ +CH3Br->CH3Li\ +LiBr}}}$ 

As for lithium to by-produce bromide, methyl lithium usually exists as this complex to form methyl lithium and a complex. When methyl lithium which does not include halide is necessary, a complex thing is used by chloromethane [¹]. Because the lithium chloride does not do methyl lithium and most 錯形成 and precipitates in ether solvents, pure methyl lithium is provided if I filter it and remove it.

Reaction

The nucleophilicity is high at the same time to be a strong base. The carbon atom reacts with a 求電子剤 and proton grant agent with a negative charge formally. I am used as methylator, a re-thiation agent mainly.

For example, it is become lithio when ferrocene works with methyl lithium. I react with the tetrahydrofuran used as a solvent by organic chemistry. I react with water and the alcohol intensely. Because the reaction using methyl lithium is greatly exothermic in many cases, it is necessary to perform it at low temperature.

Methyl lithium is used as a methyl anionic equivalent body. I methylate it when I react it with ketone, and the third grade alcohol is provided when I hydrolyze an intermediate.

${\displaystyle {\ce {R2C=O\ +CH3Li->R2C(CH3)\ -OLi}}}$ 

${\displaystyle {\ce {R2C(CH3)\ -OLi\ +H2O->R2C(CH3)\ -OH\ +LiOH}}}$ 

I give the product which methyl radical was introduced into when I trigger it to nonmetal halide. I exemplify a reaction with phosphorus trichloride.

${\displaystyle {\ce {2Li\ +CH3Br->CH3Li\ +LiBr}}}$ 

${\displaystyle {\ce {PCl3\ +3CH3Li->P(CH3)3\ +3LiCl}}}$ 

Generally, I can handle it more safely, and methyl magnesium halide having equal reactivity is used for the purpose mentioned above.

I can compose the transition metal complex having methyl radical using methyl lithium.

${\displaystyle {\ce {ZrCl4\ +6CH3Li->Li2Zr(CH3)6\ +4LiCl}}}$ 

Structure

From NMR spectroscopy of single-crystal X-ray crystallographic analysis and ⁶Li, ⁷Li, ¹³C, two kinds of structure is confirmed. One is a tetrameric cluster with form such as crooked キュバン, and a carbon atom and the lithium atom are located in the top of the cube each. The distance between Li - Li is 2.68Å, and this is approximately equal to the distance in Li₂ molecules in a vapor phase. The distance between the C-Li is 2.31Å. The carbon atom is combined with the lithium atom of three hydrogen atoms, three each. (CH₃Li)₄ does not have volatility, and it is indissolubility, but this depends on the chin stick interaction between the cluster in hydrocarbon solvent. Because the interaction between the cluster is held in check in the case of tetrameric (tert-C₄H₉Li)₄ of more bulky tert-butylithium by three-dimensional repulsion, I have volatility, solubility [²].

   

It is the cluster of the crooked hexahedron type that Li and C were placed in the top with a hexamer in turn each one more.

   

It is decided which cluster is easy to be formed by having solvent and additive (lithium bromide) or not. A tetramer is easy to be provided in [3], ether solvents a hexamer in hydrocarbon solvent such as benzene.

Combination

The cluster mentioned above is the compound that the electron including the atom which does not satisfy octet 則 is lacking in it. In other words, I do not have enough electrons to form 2 center 2 electronic couplings seen in a general organic compound. The hexamer has 30 electronic (valence electron), but 18 of those are used for C-H combination, and I stay, and 12 are used for clustering. Six electrons are assigned to lithium - lithium combination, and six methyl radical forms combination of η ^type 3 with a lithium atom by an electron by one each.

The C-Li-binding energy is estimated at 57 kcal/mol by the IR measurement [³].

References

1. ^ Lusch, M. J.; Phillips, M. V.; Sieloff, W. V.; Nomura, G. S.; House, H. O. (1984), "Preparation of Low-Halide Methyllithium," it is Org. Synth. 62:101, http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv7p0346, Coll. Vol. 7: 346.
2. ^ Elschenbroich, C. "Organometallics"; Wiley-VCH: Weinheim, 2006. ISBN 3527293906.
3. ^ ^{a b} Brown, T. L.; Rogers, M. T. (1957). "The Preparation and Properties of Crystalline Lithium Alkyls." J. Am. Chem. Soc. 79: 1859–1861. doi: 10.1021/ja01565a024. 

Allied item

• n-butylithium
• sec-butylithium
• tert-butylithium

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