Phenyllithium

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Phenyllithium
Phenyllithium.svg
Phenyllithium-chain-from-xtal-Mercury-3D-balls.png
Names
Systematic IUPAC name
Phenyllithium [1]
Other names
Lithiobenzene [2]
Identifiers
3D model (JSmol)
AbbreviationsLiPh, PhLi
506502
ChEBI
ChemSpider
ECHA InfoCard 100.008.838 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 209-720-1
2849
MeSH phenyllithium
PubChem CID
  • InChI=1S/C6H5.Li/c1-2-4-6-5-3-1;/h1-5H; X mark.svgN
    Key: NHKJPPKXDNZFBJ-UHFFFAOYSA-N X mark.svgN
  • [Li]c1ccccc1
Properties
LiC
6
H
5
Molar mass 84.045 g mol−1
AppearanceColorless crystals
Density 828 mg cm−3
Boiling point 140 to 143 °C (284 to 289 °F; 413 to 416 K)
Reacts
Thermochemistry
48.3-52.5 kJ mol−1
Hazards
GHS labelling:
GHS-pictogram-flamme.svg GHS-pictogram-acid.svg GHS-pictogram-exclam.svg
Danger
H226, H250, H261, H302, H312, H314, H332
P210, P222, P231+P232, P233, P240, P241, P242, P243, P260, P261, P264, P270, P271, P280, P301+P312, P301+P330+P331, P302+P334, P302+P352, P303+P361+P353, P304+P312, P304+P340, P305+P351+P338, P310, P312, P321, P322, P330, P363, P370+P378, P402+P404, P403+P235, P405, P422, P501
Safety data sheet (SDS) External MSDS
Related compounds
Related compounds
phenylcopper, phenylsodium, phenylcobalt
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
X mark.svgN  verify  (what is  Yes check.svgYX mark.svgN ?)

Phenyllithium is an organometallic agent with the empirical formula C6H5Li. It is most commonly used as a metalating agent in organic syntheses and a substitute for Grignard reagents for introducing phenyl groups in organic syntheses. [3] Crystalline phenyllithium is colorless; however, solutions of phenyllithium are various shades of brown or red depending on the solvent used and the impurities present in the solute. [4]

Contents

Preparation

Phenyllithium was first produced by the reaction of lithium metal with diphenylmercury: [5]

(C6Η5)2Ηg + 2Li → 2C6Η5Li + Ηg

Reaction of a phenyl halide with lithium metal produces phenyllithium:

X-Ph + 2Li → Ph-Li + LiX

Phenyllithium can also be synthesized with a metal-halogen exchange reaction:

n-BuLi + X-Ph → n-BuX + Ph-Li

The predominant method of producing phenyllithium today are the latter two syntheses.

Reactions

The primary use of PhLi is to facilitate formation of carbon-carbon bonds by nucleophilic addition and substitution reactions:

PhLi + R2C=O → PhR2COLi

2-Phenylpyridine is prepared by the reaction of phenyl lithium with pyridine, a process that entails an addition-elimination pathway: [6]

C6H5Li + C5H5N → C6H5-C5H4N + LiH

Structure and properties

Ball-and-stick model for the unsolvated phenyllithium crystal "ladder" Phenyllithium-chain-from-xtal-Mercury-3D-balls.png
Ball-and-stick model for the unsolvated phenyl­lithium crystal "ladder"

Phenyllithium is an organolithium compound that forms monoclinic crystals. Solid phenyl­lithium can be described as consisting of dimeric Li2Ph2 subunits. The Li atoms and the ipso carbons of the phenyl rings form a planar four-membered ring. The plane of the phenyl groups are perpendicular to the plane of this Li2C2 ring. Additional strong inter­molecular bonding occurs between these phenyllithium dimers and the π-electrons of the phenyl groups in the adjacent dimers, resulting in an infinite polymeric ladder structure. [7]

Stick model (ethyl groups omitted for clarity) of a phenyllithium etherate tetramer crystal Phenyllithium-etherate-tetramer-from-xtal-Mercury-3D-sticks.png
Stick model (ethyl groups omitted for clarity) of a phenyl­lithium etherate tetramer crystal

In solution, it takes a variety of structures dependent on the organic solvent. In tetrahydrofuran, it equilibrates between monomer and dimer states. In ether, as it is commonly sold, phenyllithium exists as a tetramer. Four Li atoms and four ipso carbon centers occupy alter­nating vertices of a distorted cube. Phenyl groups are at the faces of the tetrahedron and bind to three of the nearest Li atoms.

The C–Li bond lengths are an average of 2.33 Å. An ether molecule binds to each of the Li sites through its oxygen atom. In the presence of LiBr, a byproduct of directly reacting lithium with a phenyl halide, the [(PhLi•Et2O)4] complex instead becomes [(PhLi•Et2O)3•LiBr]. The Li atom of LiBr occupies one of the lithium sites in the cubane-type cluster and Br atom sits in an adjacent carbon site. [8]

Related Research Articles

<span class="mw-page-title-main">Gilman reagent</span> Class of chemical compounds

A Gilman reagent is a diorganocopper compound with the formula Li[CuR2], where R is an alkyl or aryl. They are colorless solids.

<span class="mw-page-title-main">Organolithium reagent</span> Chemical compounds containing C–Li bonds

In organometallic chemistry, organolithium reagents are chemical compounds that contain carbon–lithium (C–Li) bonds. These reagents are important in organic synthesis, and are frequently used to transfer the organic group or the lithium atom to the substrates in synthetic steps, through nucleophilic addition or simple deprotonation. Organolithium reagents are used in industry as an initiator for anionic polymerization, which leads to the production of various elastomers. They have also been applied in asymmetric synthesis in the pharmaceutical industry. Due to the large difference in electronegativity between the carbon atom and the lithium atom, the C−Li bond is highly ionic. Owing to the polar nature of the C−Li bond, organolithium reagents are good nucleophiles and strong bases. For laboratory organic synthesis, many organolithium reagents are commercially available in solution form. These reagents are highly reactive, and are sometimes pyrophoric.

<span class="mw-page-title-main">Enolate</span> Organic anion formed by deprotonating a carbonyl (>C=O) compound

In organic chemistry, enolates are organic anions derived from the deprotonation of carbonyl compounds. Rarely isolated, they are widely used as reagents in the synthesis of organic compounds.

<span class="mw-page-title-main">Triphenylphosphine</span> Chemical compound

Triphenylphosphine (IUPAC name: triphenylphosphane) is a common organophosphorus compound with the formula P(C6H5)3 and often abbreviated to PPh3 or Ph3P. It is versatile compound that is widely used as a reagent in organic synthesis and as a ligand for transition metal complexes, including ones that serve as catalysts in organometallic chemistry. PPh3 exists as relatively air stable, colorless crystals at room temperature. It dissolves in non-polar organic solvents such as benzene and diethyl ether.

Metalation is a chemical reaction that forms a bond to a metal. This reaction usually refers to the replacement of a halogen atom in an organic molecule with a metal atom, resulting in an organometallic compound. In the laboratory, metalation is commonly used to activate organic molecules during the formation of C—X bonds, which are necessary for the synthesis of many organic molecules.

<i>n</i>-Butyllithium Chemical compound

n-Butyllithium C4H9Li (abbreviated n-BuLi) is an organolithium reagent. It is widely used as a polymerization initiator in the production of elastomers such as polybutadiene or styrene-butadiene-styrene (SBS). Also, it is broadly employed as a strong base (superbase) in the synthesis of organic compounds as in the pharmaceutical industry.

The Reformatsky reaction is an organic reaction which condenses aldehydes or ketones with α-halo esters using metallic zinc to form β-hydroxy-esters:

The Shapiro reaction or tosylhydrazone decomposition is an organic reaction in which a ketone or aldehyde is converted to an alkene through an intermediate hydrazone in the presence of 2 equivalents of organolithium reagent. The reaction was discovered by Robert H. Shapiro in 1967. The Shapiro reaction was used in the Nicolaou Taxol total synthesis. This reaction is very similar to the Bamford–Stevens reaction, which also involves the basic decomposition of tosyl hydrazones.

<span class="mw-page-title-main">Grignard reagent</span> Organometallic compounds used in organic synthesis

Grignard reagents or Grignard compounds are chemical compounds with the general formula R−Mg−X, where X is a halogen and R is an organic group, normally an alkyl or aryl. Two typical examples are methylmagnesium chloride Cl−Mg−CH3 and phenylmagnesium bromide (C6H5)−Mg−Br. They are a subclass of the organomagnesium compounds.

<span class="mw-page-title-main">Methyllithium</span> Chemical compound

Methyllithium is the simplest organolithium reagent, with the empirical formula CH3Li. This s-block organometallic compound adopts an oligomeric structure both in solution and in the solid state. This highly reactive compound, invariably used in solution with an ether as the solvent, is a reagent in organic synthesis as well as organometallic chemistry. Operations involving methyllithium require anhydrous conditions, because the compound is highly reactive towards water. Oxygen and carbon dioxide are also incompatible with MeLi. Methyllithium is usually not prepared, but purchased as a solution in various ethers.

<span class="mw-page-title-main">Organozinc chemistry</span>

Organozinc chemistry is the study of the physical properties, synthesis, and reactions of organozinc compounds, which are organometallic compounds that contain carbon (C) to zinc (Zn) chemical bonds.

<span class="mw-page-title-main">Organocopper chemistry</span> Compound with carbon to copper bonds

Organocopper chemistry is the study of the physical properties, reactions, and synthesis of organocopper compounds, which are organometallic compounds containing a carbon to copper chemical bond. They are reagents in organic chemistry.

<i>sec</i>-Butyllithium Chemical compound

sec-Butyllithium is an organometallic compound with the formula CH3CHLiCH2CH3, abbreviated sec-BuLi or s-BuLi. This chiral organolithium reagent is used as a source of sec-butyl carbanion in organic synthesis.

<span class="mw-page-title-main">Diphenyl diselenide</span> Chemical compound

Diphenyl diselenide is the chemical compound with the formula (C6H5)2Se2, abbreviated Ph2Se2. This yellow-coloured solid is the oxidized derivative of benzeneselenol. It is used as a source of the PhSe unit in organic synthesis.

<span class="mw-page-title-main">Organotitanium chemistry</span>

Organotitanium chemistry is the science of organotitanium compounds describing their physical properties, synthesis, and reactions. Organotitanium compounds in organometallic chemistry contain carbon-titanium chemical bonds. They are reagents in organic chemistry and are involved in major industrial processes.

<span class="mw-page-title-main">Lithium bis(trimethylsilyl)amide</span> Chemical compound

Lithium bis(trimethylsilyl)amide is a lithiated organosilicon compound with the formula LiN(Si(CH3)3)2. It is commonly abbreviated as LiHMDS or Li(HMDS) (lithium hexamethyldisilazide - a reference to its conjugate acid HMDS) and is primarily used as a strong non-nucleophilic base and as a ligand. Like many lithium reagents, it has a tendency to aggregate and will form a cyclic trimer in the absence of coordinating species.

Organomanganese chemistry is the chemistry of organometallic compounds containing a carbon to manganese chemical bond. In a 2009 review, Cahiez et al. argued that as manganese is cheap and benign, organomanganese compounds have potential as chemical reagents, although currently they are not widely used as such despite extensive research.

<span class="mw-page-title-main">Organobismuth chemistry</span>

Organobismuth chemistry is the chemistry of organometallic compounds containing a carbon to bismuth chemical bond. Applications are few. The main bismuth oxidation states are Bi(III) and Bi(V) as in all higher group 15 elements. The energy of a bond to carbon in this group decreases in the order P > As > Sb > Bi. The first reported use of bismuth in organic chemistry was in oxidation of alcohols by Frederick Challenger in 1934 (using Ph3Bi(OH)2). Knowledge about methylated species of bismuth in environmental and biological media is limited.

<span class="mw-page-title-main">Phenylsodium</span> Chemical compound

Phenylsodium C6H5Na is an organosodium compound. Solid phenylsodium was first isolated by Nef in 1903. Although the behavior of phenylsodium and phenyl magnesium bromide are similar, the organosodium compound is very rarely used.

In organometallic chemistry, metal–halogen exchange is a fundamental reaction that converts an organic halide into an organometallic product. The reaction commonly involves the use of electropositive metals and organochlorides, bromides, and iodides. Particularly well-developed is the use of metal–halogen exchange for the preparation of organolithium compounds.

References

  1. "phenyllithium (CHEBI:51470)". Chemical Entities of Biological Interest (ChEBI). Cambridge, UK: European Bioinformatics Institute. 2009-01-22. Main. Retrieved 2013-06-01.
  2. Typically used to describe substituted derivatives. See, e.g., Katsutoshi Kobayashi; Soichi Sato; Horn, Ernst; Naomichi Furukawa (1998), "First isolation and characterization of sulfenium cation salts stabilized by the coordination of two nitrogen atoms," Tetrahedron Letters, 39: 17, pp. 2593-2596. ISSN 0040-4039. DOI 10.1016/S0040-4039(98)00277-9.
  3. Wietelmann, U.; Bauer, R. J. "Lithium and Lithium Compounds". Ullmann's Encyclopedia of Industrial Chemistry . Weinheim: Wiley-VCH. doi:10.1002/14356007.a15_393. ISBN   978-3527306732.
  4. Gilman, H.; Zoellner, E. A.; Selby, W. M. (1932). "An Improved Procedure for the Preparation of Organolithium Compounds". Journal of the American Chemical Society . 54 (5): 1957–1962. doi:10.1021/ja01344a033.
  5. Green, D. P.; Zuev, D. (2008). "Phenyllithium". Encyclopedia of Reagents for Organic Synthesis. Wiley and Sons. doi:10.1002/047084289X.rp076.pub2. ISBN   978-0471936237.
  6. Evans, J. C. W.; Allen, C. F. H. "2-Phenylpyridine" Organic Syntheses (1938), vol. 18, p. 70 doi : 10.15227/orgsyn.018.0070
  7. Dinnebier, R. E.; Behrens, U.; Olbrich, F. (1998). "Lewis Base-Free Phenyllithium: Determination of the Solid-State Structure by Synchrotron Powder Diffraction". Journal of the American Chemical Society . 120 (7): 1430–1433. doi:10.1021/ja972816e.
  8. Hope, H.; Power, P. P. (1983). "Isolation and Crystal Structures of the Halide-Free and Halide-Rich Phenyllithium Etherate Complexes [(PhLi•Et2O)4] and [(PhLi•Et2O)3•LiBr]". Journal of the American Chemical Society. 105 (16): 5320–5324. doi:10.1021/ja00354a022.