Isopropylmagnesium chloride

Last updated
Isopropylmagnesium chloride
IPrMgCl.png
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.012.680 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 213-947-1
PubChem CID
UNII
  • InChI=1S/C3H7.ClH.Mg/c1-3-2;;/h3H,1-2H3;1H;/q-1;;+2/p-1
    Key: IUYHWZFSGMZEOG-UHFFFAOYSA-M
  • C[CH-]C.[Mg+2].[Cl-]
Properties
C3H7ClMg
Molar mass 102.84 g·mol−1
Solubility Ethyl ether
Hazards
GHS labelling:
GHS-pictogram-flamme.svg GHS-pictogram-acid.svg
Danger
H225, H260, H314
P210, P223, P231+P232, P233, P240, P241, P242, P243, P260, P264, P280, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P310, P321, P335+P334, P363, P370+P378, P402+P404, P403+P235, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Isopropylmagnesium chloride is an organometallic compound with the general formula (CH3)2HCMgCl. This highly flammable, colorless, and moisture sensitive material is the Grignard reagent derived from isopropyl chloride. It is commercially available, usually as a solution in tetrahydrofuran.

Contents

Synthesis and reactivity

Solutions of isopropylmagnesium chloride by treating isopropyl chloride with magnesium metal in refluxing ether: [1]

(CH3)2HCCl + Mg → (CH3)2HCMgCl

This reagent is used to prepare other Grignard reagents by transmetalation. [2] An illustrative reaction involves the generation of the Grignard reagent derived from bromo-3,5-bis(trifluoromethyl)benzene: [3]

(CH3)2HCMgCl + (CF3)2C6H3Br → (CH3)2HCCl + (CF3)2C6H3MgBr

Addition of one equivalent of LiCl to isopropylmagnesium chloride gives "Turbo Grignard" solutions, named so due to the increased rate and efficiency for transmetalation reactions. [4] [5]

Isopropylmagnesium chloride is also used to prepare isopropyl compounds, such as chlorodiisopropylphosphine: [6]

PCl3 + 2 (CH3)2CHMgCl → [(CH3)2CH]2PCl + 2 MgCl2

This reaction exploits the bulky nature of the isopropyl substituent.

Turbo-Grignard reagents

As initially reported by Knochel et al., [7] lithium chloride, isopropylmagnesium chloride enhances the ability of isopropylmagnesium chloride toward transmetalation reactions. The more reactive species, a LiCl-iPrMgCl complex, is called a Turbo-Grignard reagent. These species are related to Turbo-Hauser bases, a family of magnesium amido compounds containing also LiCl. [8] "Turbo-Grignards", as they are often called, are aggregates with the formula [i-PrMgCl·LiCl]2. These species promote formation of aryl and heteroaryl Grignard reagents by halogen-magnesium exchange: [9]

fast, homogeneous: XC6H4Br + i−PrMgCl·LiCl → XC6H4MgCl·LiCl + i−PrCl + MgBrCl

The traditional method for generating the aryl Grignard reagent proceeds less predictably:

slow, heterogeneous: XC6H4Br + Mg → XC6H4MgBr

Furthermore, traditional routes to Grignard reagents has limited functional group compatibility, whereas the Turbo-Grignard method tolerates other halides, some ester groups, and nitriles.

Related Research Articles

<span class="mw-page-title-main">Grignard reaction</span> Organometallic coupling reaction

The Grignard reaction is an organometallic chemical reaction in which, according to the classical definition, carbon alkyl, allyl, vinyl, or aryl magnesium halides are added to the carbonyl groups of either an aldehyde or ketone under anhydrous conditions. This reaction is important for the formation of carbon–carbon bonds.

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. Haloarenes 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.

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 Corey–House synthesis (also called the Corey–Posner–Whitesides–House reaction and other permutations) 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.

The Schlenk equilibrium, named after its discoverer Wilhelm Schlenk, is a chemical equilibrium taking place in solutions of Grignard reagents and Hauser bases

<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.

The Negishi coupling is a widely employed transition metal catalyzed cross-coupling reaction. The reaction couples organic halides or triflates with organozinc compounds, forming carbon-carbon bonds (C-C) in the process. A palladium (0) species is generally utilized as the catalyst, though nickel is sometimes used. A variety of nickel catalysts in either Ni0 or NiII oxidation state can be employed in Negishi cross couplings such as Ni(PPh3)4, Ni(acac)2, Ni(COD)2 etc.

<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">Group 2 organometallic chemistry</span>

Group 2 organometallic chemistry refers to the organic derivativess of any group 2 element. It is a subtheme to main group organometallic chemistry. By far the most common group 2 organometallic compounds are the magnesium-containing Grignard reagents which are widely used in organic chemistry. Other organometallic group 2 compounds are typically limited to academic interests.

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">Tetrakis(3,5-bis(trifluoromethyl)phenyl)borate</span> Chemical compound

Tetrakis[3,5-bis(trifluoromethyl)phenyl]borate is an anion with chemical formula [{3,5-(CF3)2C6H3}4B], which is commonly abbreviated as [BArF4], indicating the presence of fluorinated aryl (ArF) groups. It is sometimes referred to as Kobayashi's anion in honour of Hiroshi Kobayashi who led the team that first synthesised it. More commonly it is affectionately nicknamed "BARF." The BARF ion is also abbreviated BArF24, to distinguish it from the closely related BArF
20
, [(C6F5)4B]. However, for a small group of chemists, the anion is abbreviated as TFPB otherwise, short for Tetrakis[3,5-bis(triFluoromethyl)Phenyl]Borate.

<i>tert</i>-Butylthiol Chemical compound

tert-Butylthiol, also known as tert-butyl mercaptan (TBM), and abbreciated t-BuSH, is an organosulfur compound with the formula (CH3)3CSH. This thiol has a strong odor. It is considered a flavoring agent.

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

Organocerium chemistry is the science of organometallic compounds that contain one or more chemical bond between carbon and cerium. These compounds comprise a subset of the organolanthanides. Most organocerium compounds feature Ce(III) but some Ce(IV) derivatives are known.

Hauser bases, also called magnesium amide bases, are magnesium compounds used in organic chemistry as bases for metalation reactions. These compounds were first described by Charles R. Hauser in 1947. Compared with organolithium reagents, the magnesium compounds have more covalent, and therefore less reactive, metal-ligand bonds. Consequently, they display a higher degree of functional group tolerance and a much greater chemoselectivity. Generally, Hauser bases are used at room temperature while reactions with organolithium reagents are performed at low temperatures, commonly at −78 °C.

<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.

Radical fluorination is a type of fluorination reaction, complementary to nucleophilic and electrophilic approaches. It involves the reaction of an independently generated carbon-centered radical with an atomic fluorine source and yields an organofluorine compound.

Turbo-Hauser bases are amido magnesium halides that contain stoichiometric amounts of LiCl. These mixed Mg/Li amides of the type R2NMgCl⋅LiCl are used in organic chemistry as non-nucleophilic bases for metalation reactions of aromatic and heteroaromatic substrates. Compared to their LiCl free ancestors Turbo-Hauser bases show an enhanced kinetic basicity, excellent regioselectivity, high functional group tolerance and a better solubility.

Paul Knochel is a French chemist and a member of the French Academy of Sciences.

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.

A magnesium(I) dimer is a molecular compound containing a magnesium to magnesium bond (Mg-Mg), giving the metal an apparent +1 oxidation state. Alkaline earth metals are commonly found in the +2-oxidation state, such as magnesium. The M2+ are considered as redox-inert, meaning that the +2 state is significant. However, recent advancements in main group chemistry have yielded low-valent magnesium(I) dimers, also given as Mg(I), with the first compound being reported in 2007. They can be generally represented as LMg-MgL, with L being a monoanionic ligand. For example, β-diketiminate, commonly referred to as Nacnac, is a useful chelate regarding these complexes. By tuning the ligand, the thermodynamics of the complex change. For instance, the ability to add substituents onto Nacnac can contribute to the steric bulk, which can affect reactivity and stability. As their discovery has grown, so has their usefulness. They are employed in organic and inorganic reduction reactions. It is soluble in a hydrocarbon solvent, like toluene, stoichiometric, selective, and safe.

References

  1. Seyferth, Dietmar (2009-03-23). "The Grignard Reagents". Organometallics. 28 (6): 1598–1605. doi:10.1021/om900088z. ISSN   0276-7333.
  2. Knochel, P.; Dohle, W.; Gommermann, N.; Kneisel, F. F.; Kopp, F.; Korn, T.; Sapountzis, I.; Vu, V. A. (2003). "Highly Functionalized Organomagnesium Reagents Prepared through Halogen–Metal Exchange". Angewandte Chemie International Edition. 42 (36): 4302–4320. doi:10.1002/anie.200300579. PMID   14502700.
  3. Johnnie L. Leazer Jr; Raymond Cvetovich (2005). "A Practical and Safe Preparation of 3,5-Bis(trifluoromethyl)acetophenone". Org. Synth. 82: 115. doi:10.15227/orgsyn.082.0115.
  4. Krasovskiy, Arkady; Knochel, Paul (2004-06-21). "A LiCl‐Mediated Br/Mg Exchange Reaction for the Preparation of Functionalized Aryl‐ and Heteroarylmagnesium Compounds from Organic Bromides". Angewandte Chemie International Edition. 43 (25): 3333–3336. doi:10.1002/anie.200454084. ISSN   1433-7851.
  5. Hermann, Andreas; Seymen, Rana; Brieger, Lukas; Kleinheider, Johannes; Grabe, Bastian; Hiller, Wolf; Strohmann, Carsten (2023-06-19). "Comprehensive Study of the Enhanced Reactivity of Turbo‐Grignard Reagents**". Angewandte Chemie International Edition. 62 (25). doi: 10.1002/anie.202302489 . ISSN   1433-7851.
  6. W. Voskuil; J. F. Arens (1968). "Chlorodiisopropylphosphine". Org. Synth. 48: 47. doi:10.15227/orgsyn.048.0047.
  7. Krasovskiy, A.; Knochel, P. (2004). "A LiCl-Mediated Br/Mg Exchange Reaction for the Preparation of Functionalized Aryl- and Heteroarylmagnesium Compounds from Organic Bromides". Angew. Chem. Int. Ed. 43 (25): 3333–3336. doi:10.1002/anie.200454084. PMID   15213967.
  8. Li-Yuan Bao, Robert; Zhao, Rong; Shi, Lei (2015). "Progress and Developments in the turbo Grignard Reagent i-PrMgCl·LiCl: A Ten-Year Journey". Chemical Communications. 51 (32): 6884–6900. doi:10.1039/c4cc10194d. PMID   25714498.
  9. Knochel, Paul; Gavryushin, Andrei (2010). "Lithium Dichloro(1-methylethyl)-magnesate". Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rn01161. ISBN   978-0-471-93623-7.