Dimethylzinc

Last updated
Dimethylzinc
Dimethylzinc-3D-balls.png
White: H, Black: C, Grey: Zn
Names
IUPAC name
Dimethylzinc
Other names
  • 2-Zincapropane
  • Dimethyl zinc
  • Dimethylzincane
  • DMZ
  • DMZn
  • Methylzinc
  • Zinc carbanide
  • Zinc methanide
  • Zinc methyl
  • Zinc trihydrogenmethanide
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.008.077 OOjs UI icon edit-ltr-progressive.svg
PubChem CID
UNII
  • InChI=1S/2CH3.Zn/h2*1H3; Yes check.svgY
    Key: AXAZMDOAUQTMOW-UHFFFAOYSA-N Yes check.svgY
  • InChI=1/2CH3.Zn/h2*1H3;/rC2H6Zn/c1-3-2/h1-2H3
    Key: AXAZMDOAUQTMOW-WPFVDKAYAX
  • C[Zn]C
Properties
Zn(CH3)2
Molar mass 95.478 g/mol
AppearanceColorless liquid
Odor Garlic [1]
Density 1.386 g/cm3 at 10.5 °C [1]
Melting point −42 °C (−44 °F; 231 K)
Boiling point 46 °C (115 °F; 319 K)
Solubility Soluble in xylene, diethyl ether, hydrocarbons; decomposes in water, ethanol and acids [1]
Vapor pressure 50.13 kPa [1]
Thermal conductivity 0.1627 W/(m∙K) at 70 °C (158 °F) [1]
Viscosity 0.807 mPa·s at 70 °F (21 °C) [1]
Thermochemistry
129.20 J/(mol∙K) (liquid at 25 °C (77 °F)) [2]
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
Spontaneously ignites in air and violently reacts with water, evolving irritant and toxic fumes. [1]
GHS labelling:
GHS-pictogram-flamme.svg GHS-pictogram-acid.svg GHS-pictogram-pollu.svg
Danger
H225, H250, H260, H314, H410
P210, P222, P223, P231+P232, P233, P235, P240, P241, P242, P243, P260, P264, P273, P280, P301+P330+P331, P302, P303+P361+P353, P304+P340, P305, P316, P317, P321, P334, P335, P338, P361, P363, P370+P378, P391, P402+P404, P403, P405, P501
NFPA 704 (fire diamond)
NFPA 704.svgHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 4: Will rapidly or completely vaporize at normal atmospheric pressure and temperature, or is readily dispersed in air and will burn readily. Flash point below 23 °C (73 °F). E.g. propaneInstability 3: Capable of detonation or explosive decomposition but requires a strong initiating source, must be heated under confinement before initiation, reacts explosively with water, or will detonate if severely shocked. E.g. hydrogen peroxideSpecial hazard W: Reacts with water in an unusual or dangerous manner. E.g. sodium, sulfuric acid
3
4
3
W
0 °F (−18 °C) [1]
Related compounds
Related compounds
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 ?)

Dimethylzinc, also known as zinc methyl, DMZ, or DMZn, is an organozinc compound with the chemical formula Zn(C H 3)2. It belongs to the large series of similar compounds such as diethylzinc.

Contents

Preparation

It is formed by the action of methyl iodide on zinc or zinc-sodium alloy at elevated temperatures.

2 Zn + 2 CH3I → Zn(CH3)2 + ZnI2

Sodium assists the reaction of the zinc with the methyl iodide. Zinc iodide is formed as a byproduct.

Properties

Dimethylzinc is a colorless mobile volatile liquid, which has a characteristic disagreeable garlic-like odor. It is a very reactive and strong reducing agent. [1] It is soluble in alkanes and often sold as a solution in hexanes. The triple point of dimethylzinc is 230.13 K (−43.02 °C) ± 0.02 K. [2] The monomeric molecule of dimethylzinc is linear at Zn center and tetragonal at C centers.

Toxicity and hazards

Inhalation of dimethylzinc mist or vapor causes immediate irritation of the upper respiratory tract, and may cause pneumonia and death. Eyes are immediately and severely irritated and burned by liquid, vapor, or dilute solutions. If not removed by thorough flushing with water, this chemical may permanently damage the cornea, eventually causing blindness. If dimethylzinc contacts the skin, it causes thermal and acid burns by reacting with moisture on skin. Unless washed quickly, skin may be scarred. Ingestion, while unlikely, also causes immediate burns. Nausea, vomiting, cramps, and diarrhea may follow, and tissues may ulcerate if not promptly treated. Upon heating, dimethylzinc vapor decomposes to irritating and toxic products. [1]

Contact of dimethylzinc with oxidants may form explosive peroxides. Dimethylzinc oxidises in air very slowly, producing methylzinc methoxide CH3ZnOCH3.

Dimethylzinc is very pyrophoric and can spontaneously ignite in air. It burns in air with a blue flame, giving off a garlic-like odor. The products of decomposition (fire smoke) include zinc oxide, which itself is not toxic, but its fumes can irritate lungs and cause metal fume fever, severe injury, or death.

Dimethylzinc fire must be extinguished with dry sand. The fire reacts violently or explosively with water, generating very flammable methane gas which can explode in air upon catching fire, and lung-irritating smoke of zinc oxide. Dimethylzinc fire reacts violently or explosively with methanol, ethanol and 2,2-dichloropropane. It explodes in oxygen and ozone. Improperly handled containers of dimethylzinc can explode, causing serious injuries or death. [1]

Structure

In the solid state the compound exists in two modifications. The tetragonal high-temperature phase shows a two-dimensional disorder, while the low-temperature phase which is monoclinic is ordered. The molecules are linear with Zn-C bond lengths measuring 192.7(6) pm. [3] The structure of the gas-phase shows a very similar Zn-C distance of 193.0(2) pm. [4]

History

Dimethylzinc was first prepared by Edward Frankland during his work with Robert Bunsen in 1849 at the University of Marburg. After heating a mixture of zinc and methyl iodide in an airtight vessel, a flame burst out when the seal was broken. [5] In the laboratory, this synthesis method remains unchanged today, except that copper or copper compounds are used to activate the zinc.

Uses

Dimethylzinc has been of great importance in the synthesis of organic compounds. It was used for a long time to introduce methyl groups into organic molecules or to synthesize organometallic compounds containing methyl groups. Grignard reagents, (organo-magnesium compounds), which are easier to handle and less flammable, replaced organo-zinc compounds in most laboratory syntheses. Due to differences in reactivity (as well as in reaction byproducts) between organo-zinc compounds and Grignard reagents, organo-zinc compounds may be preferred in some syntheses. [6]

Its high vapor pressure has led to extensive uses in the production of semiconductors, e.g. metalorganic chemical vapor deposition (MOCVD) for the preparation of wide band gap II–VI semiconducting films (e.g. ZnO, ZnS, ZnSe, ZnTe, CdxHg1−xTe) and as p-dopant precursors for III–V semiconductors (e.g. AlN, AlP, AlxGa1−xAs, GaAs, InP), which have many electronic and photonic applications. [7]

It is used as an accelerator in rubber vulcanization, as a fungicide, and as a methylating agent in methyltitanium trichloride.

Related Research Articles

<span class="mw-page-title-main">Organometallic chemistry</span> Study of organic compounds containing metal(s)

Organometallic chemistry is the study of organometallic compounds, chemical compounds containing at least one chemical bond between a carbon atom of an organic molecule and a metal, including alkali, alkaline earth, and transition metals, and sometimes broadened to include metalloids like boron, silicon, and selenium, as well. Aside from bonds to organyl fragments or molecules, bonds to 'inorganic' carbon, like carbon monoxide, cyanide, or carbide, are generally considered to be organometallic as well. Some related compounds such as transition metal hydrides and metal phosphine complexes are often included in discussions of organometallic compounds, though strictly speaking, they are not necessarily organometallic. The related but distinct term "metalorganic compound" refers to metal-containing compounds lacking direct metal-carbon bonds but which contain organic ligands. Metal β-diketonates, alkoxides, dialkylamides, and metal phosphine complexes are representative members of this class. The field of organometallic chemistry combines aspects of traditional inorganic and organic chemistry.

The Simmons–Smith reaction is an organic cheletropic reaction involving an organozinc carbenoid that reacts with an alkene to form a cyclopropane. It is named after Howard Ensign Simmons, Jr. and Ronald D. Smith. It uses a methylene free radical intermediate that is delivered to both carbons of the alkene simultaneously, therefore the configuration of the double bond is preserved in the product and the reaction is stereospecific.

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.

<span class="mw-page-title-main">Barbier reaction</span> Reaction in organic chemistry

The Barbier reaction is an organometallic reaction between an alkyl halide, a carbonyl group and a metal. The reaction can be performed using magnesium, aluminium, zinc, indium, tin, samarium, barium or their salts. The reaction product is a primary, secondary or tertiary alcohol. The reaction is similar to the Grignard reaction but the crucial difference is that the organometallic species in the Barbier reaction is generated in situ, whereas a Grignard reagent is prepared separately before addition of the carbonyl compound. Unlike many Grignard reagents, the organometallic species generated in a Barbier reaction are unstable and thus cannot be stored or sold commercially. Barbier reactions are nucleophilic addition reactions that involve relatively inexpensive, water insensitive metals or metal compounds. For this reason, it is possible in many cases to run the reaction in water, making the procedure part of green chemistry. In contrast, Grignard reagents and organolithium reagents are highly moisture sensitive and must be used under an inert atmosphere without the presence of water. The Barbier reaction is named after Philippe Barbier, who was Victor Grignard's teacher.

The Blaise ketone synthesis is the chemical reaction of acid chlorides with organozinc compounds to give ketones.

<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">Diethylzinc</span> Chemical compound

Diethylzinc (C2H5)2Zn, or DEZ, is a highly pyrophoric and reactive organozinc compound consisting of a zinc center bound to two ethyl groups. This colourless liquid is an important reagent in organic chemistry. It is available commercially as a solution in hexanes, heptane, or toluene, or as a pure liquid.

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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">Organocadmium chemistry</span>

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

Decamethyldizincocene is an organozinc compound with the formula [Zn25–C5Me5)2]. It is the first and an unusual example of a compound with a Zn-Zn bond. Decamethyldizincocene is a colorless crystalline solid that burns spontaneously in the presence of oxygen and reacts with water. It is stable at room temperature and especially soluble in diethyl ether, benzene, pentane, or tetrahydrofuran.

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

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References

  1. 1 2 3 4 5 6 7 8 9 10 11 "Dimethylzinc".
  2. 1 2 "Dimethylzinc (CAS 544-97-8)".
  3. John Bacsa; Felix Hanke; Sarah Hindley; Rajesh Odedra; George R. Darling; Anthony C. Jones; Alexander Steiner (2011). "The Solid State Structures of Dimethylzinc and Diethylzinc". Angewandte Chemie International Edition . 50 (49): 11685–11687. doi:10.1002/anie.201105099. PMC   3326375 . PMID   21919175.
  4. A. Haaland; J. C. Green; G. S. McGrady; A. J. Downs; E. Gullo; M. J. Lyall; J. Timberlake; A. V. Tutukin; H. V. Volden; K.-A. Østby (2003). "The length, strength and polarity of metal–carbon bonds: dialkylzinc compounds studied by density functional theory calculations, gas electron diffraction and photoelectron spectroscopy". Dalton Transactions (22): 4356–4366. doi:10.1039/B306840B.
  5. E. Frankland (1849). "Notiz über eine neue Reihe organischer Körper, welche Metalle, Phosphor u. s. w. enthalten". Liebigs Annalen der Chemie und Pharmacie . 71 (2): 213–216. doi:10.1002/jlac.18490710206.
  6. Erdik, Ender (1996). Organozinc reagents in organic synthesis. Boca Raton: CRC Press. ISBN   978-0-8493-9151-4.
  7. Mohammad Afzaal; Mohammad A. Malik; Paul O’Brien (2007). "Preparation of zinc containing materials". New Journal of Chemistry . 31 (12): 2029–2040. doi:10.1039/b712235g.