Phenylsodium

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Phenylsodium
Phenylsodium.svg
Phenylsodium-3D-balls.png
Phenylsodium-3D-vdW.png
Names
IUPAC name
Sodium benzenide
Other names
Sodium benzenide, Sodium phenyl, sodiobenzene
Identifiers
3D model (JSmol)
AbbreviationsNaPh, PhNa
ChemSpider
PubChem CID
UNII
  • InChI=1S/C6H5.Na/c1-2-4-6-5-3-1;/h1-5H;/q-1;+1
    Key: KSMWLICLECSXMI-UHFFFAOYSA-N
  • [Na]C1=CC=CC=C1
Properties
C6H5Na
Molar mass 100.096 g·mol−1
AppearanceYellowish-white powder [1]
Reacts
Solubility Insoluble in hydrocarbons, reacts with ether
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
Corrosive, pyrophoric in air
Related compounds
Related compounds
Phenyllithium, Phenylcopper, Phenylcobalt
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

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. [2]

Contents

Synthesis

The existence of phenylsodium was originally proposed by August Kekulé after observing the formation of sodium benzoate in the reaction of bromobenzene with sodium under carbon dioxide.

Transmetalation

In the original synthesis, diphenylmercury and sodium was shown to yield a suspension of phenylsodium:

(C6H5)2Hg + 3 Na → 2 C6H5Na + NaHg

The Shorigen reaction is also used in the generation of phenylsodium, where an alkyl sodium compound is treated with benzene: [3]

RNa + C6H6 → RH + C6H5Na

The method can also result in the addition of a second sodium. This dimetallation occurs in the meta and para positions. The use of certain alkyl sodium compounds such as n-amyl sodium is known to greatly increase this dimetallation effect. [4]

Metal-halogen exchange

A common route to phenylsodium utilizes powdered sodium with bromobenzene:

C6H5Br + 2 Na → C6H5Na + NaBr

The yield of this method is lowered by the formation of diphenyl due to phenylsodium reacting with aryl halide starting material [5]

Lithium exchange

A more modern synthesis involves the reaction of phenyllithium and NaOtBu: [6]

C6H5Li + NaOtBu → C6H5Na + LiOtBu

Properties and structure

Structure of the phenylsodium-PMDTA adduct, hydrogen atoms omitted for clarity. Phenylsodium-PMDTA adduct.svg
Structure of the phenylsodium-PMDTA adduct, hydrogen atoms omitted for clarity.

The first syntheses of phenylsodium which employed the organomercury route seemed to yield a light brown powder. [7] It was discovered by Wilhelm Schlenk that this product was contaminated by a sodium amalgum. Centrifugation allowed for the isolation of pure phenylsodium which appears as a yellowish-white amorphous powder which readily bursts into flames. [1]

Like phenyllithium, adducts of the compound with PMDTA have been crystallized. While phenyllithium forms a monomeric adduct with PMDTA, phenylsodium exists as a dimer, reflecting the larger radium of sodium. [6]

Complexes of phenylsodium and magnesium alkoxides, especially magnesium 2-ethoxyethoxide Mg(OCH2CH2OEt)2, are soluble in benzene. The complex is formed by the reaction:

NaPh + Mg(OCH2CH2OEt)2 → Na2MgPh2(OCH2CH2OEt)2

Although the phenylsodium is complexed, it maintains its phenylation and metalation ability. Additionally, the complex is highly stable in benzene retaining its reactivity after a month of storage. [8]

Phenyllithium can also be used to modify the properties of phenylsodium. Ordinarily, phenylsodium reacts violently with diethyl ether, but Georg Wittig showed that by synthesizing PhNa with PhLi in ether, the complex (C6H5Li)(C6H5Na)n was formed. The phenylsodium component of the complex reacts before the phenyllithium, making it an effective compound to stabilize the highly reactive sodium compound. This complex could be isolated as solid crystals which were soluble in ether and remained stable in solution at room temperature for several days. Phenyllithium is able to stabilize phenylsodium in a ratio as high as 1:24 Li:Na, although this produces an insoluble mass which could be still used for reactions. [2]

Reactions

Reactions involving phenylsodium were employed as early as the mid 19th century, although before 1903. Typically phenylsodium is prepared in situ analogous to methods used for Grignard reagents. The work of Acree provides a number of examples of reactions involving the compound. [9]

Cross-coupling

The reaction with ethyl bromide produces ethyl benzene:

NaPh + BrEt → PhEt + NaBr

An analogous reaction also occurs in the preparation of phenylsodium to produce diphenyl:

NaPh + PhBr → Ph-Ph + NaBr

Reaction of benzyl chloride and phenylsodium results in diphenylmethane and (E)-stilbene. Diphenylmethane is the expected product from the substitution of chloride. The formation of stilbene is implicates radical intermediates like those proposed in the Wurtz-Fittig reaction mechanism.

The reaction of phenylsodium with benzoyl chloride yields, after hydrolysis, triphenylcarbinol. Benzophenone is proposed as an intermediate.

2NaPh + PhCOCl → Ph3CONa + NaCl

Metallation

Metallation reactions with phenylsodium proceed in the following general form:

PhNa + RH → C6H6 + RNa

The metallation is confirmed/detected by treatment of the metallated compound with carbon dioxide, affording the corresponding sodium carboxylate which can be acidified to yield the carboxylic acid:

RNa + CO2 → RCO2Na

Metallation follows a generally predictable order of reactivity. Benzene can be metallated by alkylsodium compounds resulting in phenylsodium. The phenylsodium is then able to metallate other aromatic compounds. The most commonly used reagent for metallation by phenylsodium is toluene, producing benzylsodium. Toluene can be metallated by synthesizing phenylsodium in toluene instead of benzene:

C6H5Cl + 2Na + C6H5CH3 → C6H6 + NaCl + C6H5CH2Na

The benzylsodium can then be used in a nucleophilic addition. The effectiveness of the metallation can be determined by carbonating and isolating the phenylacetic acid product.

See also

Related Research Articles

<span class="mw-page-title-main">Ether</span> Organic compounds made of alkyl/aryl groups bound to oxygen (R–O–R)

In organic chemistry, ethers are a class of compounds that contain an ether group—an oxygen atom connected to two alkyl or aryl groups. They have the general formula R−O−R′, where R and R′ represent the alkyl or aryl groups. Ethers can again be classified into two varieties: if the alkyl or aryl groups are the same on both sides of the oxygen atom, then it is a simple or symmetrical ether, whereas if they are different, the ethers are called mixed or unsymmetrical ethers. A typical example of the first group is the solvent and anaesthetic diethyl ether, commonly referred to simply as "ether". Ethers are common in organic chemistry and even more prevalent in biochemistry, as they are common linkages in carbohydrates and lignin.

<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.

In organic chemistry, an aryl halide is an aromatic compound in which one or more hydrogen atoms, directly bonded to an aromatic ring are replaced by a halide. The haloarene are different from haloalkanes because they exhibit many differences in methods of preparation and properties. The most important members are the aryl chlorides, but the class of compounds is so broad that there are many derivatives and applications.

<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 widely used in the synthesis of organic and organometallic compounds. 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.

The Hiyama coupling is a palladium-catalyzed cross-coupling reaction of organosilanes with organic halides used in organic chemistry to form carbon–carbon bonds. This reaction was discovered in 1988 by Tamejiro Hiyama and Yasuo Hatanaka as a method to form carbon-carbon bonds synthetically with chemo- and regioselectivity. The Hiyama coupling has been applied to the synthesis of various natural products.

<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 Corey–House synthesis is an organic reaction that involves the reaction of a lithium diorganylcuprate with an organic halide or pseudohalide to form a new alkane, as well as an ill-defined organocopper species and lithium (pseudo)halide as byproducts.

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

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. 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.

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

Iodobenzene is an organoiodine compound consisting of a benzene ring substituted with one iodine atom. It is useful as a synthetic intermediate in organic chemistry. It is a volatile colorless liquid, although aged samples appear yellowish.

<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 toward 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">Organocadmium chemistry</span>

Organocadmium chemistry describes the physical properties, synthesis, reactions, and use of organocadmium compounds, which are organometallic compounds containing a carbon to cadmium chemical bond. Cadmium shares group 12 with zinc and mercury and their corresponding chemistries have much in common. The synthetic utility of organocadmium compounds is limited.

<span class="mw-page-title-main">Bis(benzene)chromium</span> Chemical compound

Bis(benzene)chromium is the organometallic compound with the formula Cr(η6-C6H6)2. It is sometimes called dibenzenechromium. The compound played an important role in the development of sandwich compounds in organometallic chemistry and is the prototypical complex containing two arene ligands.

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

Phenylmagnesium bromide, with the simplified formula C
6
H
5
MgBr
, is a magnesium-containing organometallic compound. It is commercially available as a solution in diethyl ether or tetrahydrofuran (THF). Phenylmagnesium bromide is a Grignard reagent. It is often used as a synthetic equivalent for the phenyl "Ph" synthon.

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

Sodium tetraphenylborate is the organic compound with the formula NaB(C6H5)4. It is a salt, wherein the anion consists of four phenyl rings bonded to boron. This white crystalline solid is used to prepare other tetraphenylborate salts, which are often highly soluble in organic solvents. The compound is used in inorganic and organometallic chemistry as a precipitating agent for potassium, ammonium, rubidium, and cesium ions, and some organic nitrogen compounds.

(Benzene)chromium tricarbonyl is an organometallic compound with the formula Cr(C6H6)(CO)3. This yellow crystalline solid compound is soluble in common nonpolar organic solvents. The molecule adopts a geometry known as “piano stool” because of the planar arrangement of the aryl group and the presence of three CO ligands as "legs" on the chromium-bond axis.

Organosodium chemistry is the chemistry of organometallic compounds containing a carbon to sodium chemical bond. The application of organosodium compounds in chemistry is limited in part due to competition from organolithium compounds, which are commercially available and exhibit more convenient reactivity.

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

n-Butylsodium CH3CH2CH2CH2Na is an organometallic compound with the idealized formula NaC4H9. Like other simple organosodium compounds, it is polymeric and highly basic. In contrast to n-butyllithium, n-butylsodium is only of specialized academic interest.

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

Pentaphenylantimony is an organoantimony compound containing five phenyl groups attached to one antimony atom. It has formula Sb(C6H5)5 (or SbPh5).

An arsinide, arsanide, dihydridoarsenate(1−) or arsanyl compound is a chemical derivative of arsine, where one hydrogen atom is replaced with a metal or cation. The arsinide ion has formula AsH−2. It can be considered as a ligand with name arsenido or arsanido. Researchers are unenthusiastic about studying arsanyl compounds, because of the toxic chemicals, and their instability. The IUPAC names are arsanide and dihydridoarsenate(1−). For the ligand the name is arsanido. The neutral −AsH2 group is termed arsanyl.

References

  1. 1 2 Schlenk, W.; Holtz, Johanna (January 1917). "Über die einfachsten metallorganischen Alkaliverbindungen". Berichte der Deutschen Chemischen Gesellschaft. 50 (1): 262–274. doi:10.1002/cber.19170500142.
  2. 1 2 Seyferth, Dietmar (January 2006). "Alkyl and Aryl Derivatives of the Alkali Metals: Useful Synthetic Reagents as Strong Bases and Potent Nucleophiles. 1. Conversion of Organic Halides to Organoalkali-Metal Compounds". Organometallics. 25 (1): 13. doi: 10.1021/om058054a .
  3. Schorigin, Paul (May 1908). "Synthesen mittels Natrium und Halogenalkylen". Berichte der Deutschen Chemischen Gesellschaft. 41 (2): 2114. doi:10.1002/cber.190804102208.
  4. Bryce-Smith, D.; Turner, E. E. (1953). "177. Organometallic Compounds of the Alkali Metals. Part II. The Metallation and Dimetallation of Benzene". Journal of the Chemical Society (Resumed): 861–863. doi:10.1039/jr9530000861.
  5. Jenkins, William W. (June 1942). "A Study on the Preparation of Phenyl Sodium". Master's Theses (225).
  6. 1 2 Schümann, Uwe; Behrens, Ulrich; Weiss, Erwin (April 1989). "Synthese und Struktur von Bis[μ-phenyl(pentamethyldiethylentriamin)natrium], einem Phenylnatrium-Solvat". Angewandte Chemie. 101 (4): 481–482. Bibcode:1989AngCh.101..481S. doi:10.1002/ange.19891010420.
  7. Acree, S. F. (August 1903). "On Sodium Phenyl and the Action of Sodium on Ketones (report on work by John Ulric Nef)". Journal of the American Chemical Society. 25 (8): 588–609. doi:10.1021/ja02010a026.
  8. Screttas, Constantinos G.; Micha-Screttas, Maria (June 1984). "Hydrocarbon-soluble organoalkali-metal reagents. Preparation of aryl derivatives". Organometallics. 3 (6): 904–907. doi:10.1021/om00084a014.
  9. Acree, Solomon, F (1903). On Sodium Phenyl and the Action of Sodium on Ketones. Easton, PA: Press of the Chemical Publishing Co. pp. 1–23.{{cite book}}: CS1 maint: multiple names: authors list (link)