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Diethylzinc



Diethylzinc
Identifiers
CAS number 557-20-0
SMILES CCZnCC
Properties
Molecular formula C4H10Zn
Molar mass 123.50 g/mol
Density 1.205 g/mL
Melting point

-28 °C

Boiling point

117 °C

Solubility in water Reacts violently
Hazards
EU classification Flammable (F); Corrosive (C); Dangerous for the environment (N)
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox disclaimer and references

Diethylzinc (C2H5)2Zn, or DEZ, is an organozinc compound comprised of zinc bonded to two ethyl groups. It is an important reagent in organic chemistry and available commercially as solutions of hexanes, heptane or toluene.

Additional recommended knowledge

Contents

Synthesis

Edward Frankland prepared the compound in 1848 from zinc and and ethyl iodide, the first organozinc compound discovered.[1] He improved the synthesis by using diethyl mercury as starting material [2] A classic synthesis consists of the reaction between ethyl iodide and ethyl bromide with a zinc / copper couple [3]

Reactions

Diethylzinc reacts violently with water and easily catches fire (pyrophoric) when in contact with air. It must therefore be handled under a nitrogen blanket.

Diethylzinc is used in organic synthesis as a nucleophilic ethyl synthon in addition reactions to carbonyl groups (for example in the asymmetric addition to benzaldehyde [4]) and imines [5]

With diiodomethane it forms a Simmons-Smith reagent.[6][7]

Other uses

Its reactivity meant that it was used in small quantities as a hypergolic or "self igniting" liquid rocket fuel -- it ignites on contact with oxidiser, so the rocket motor need only contain a pump, without a spark source for ignition.

Diethylzinc was also investigated for a period of many years by the United States Library of Congress as a potential means of mass deacidification of books printed on wood pulp paper. Initial experiments involved placing books within a vacuum chamber and exposing them to diethylzinc vapour. In theory, the vapour would react with acid residues in the paper, neutralizing them and leaving only slightly alkaline zinc oxide residues in the paper. Results were initially promising, showing the pH of the paper to be increased to 7.5. Larger-scale experiments did not go as well; prototypes built for the Library of Congress by Northrup left "tide marks" on the pages, caused the bindings and boards to split and warp, and left behind unpleasant odours. There was also some evidence of the pages being physically weakened, even as their acidity was reduced.

Most infamously, the final prototype suffered damage in a series of explosions from contact between trace amounts of diethylzinc with moisture in the chamber. Engineers assigned to the project were unable to account for large volumes of the chemical after the process was completed and, unable to safely dismantle the device, a demolition team from the United States Army had to be called in to destroy the device with explosives. When the charges were detonated, the "missing" DEZ--which had accreted to the walls of the tubing--caused a cataclysmic explosion, nearly destroying the warehouse that housed the prototype. As a result of this catastrophe, the Library of Congress has abandoned all investigation of DEZ as a potential deacidification agent.[8]

In microelectronics, diethylzinc is used as a doping agent.[citation needed]

References

  1. ^ E. Frankland (1850). "On the isolation of the organic radicals". Quarterly Journal of the Chemical Society 2: 263. doi:10.1039/QJ8500200263.
  2. ^ E. Frankland, B. F. Duppa (1864). "On a new reaction for the production of the zinc-compounds of the alkyl-radical". Journal of the Chemical Society 17: 29-36. doi:10.1039/JS8641700029.
  3. ^ C. R. Noller (1943). "Diethyl Zinc". Org. Synth.; Coll. Vol. 2: 184. 
  4. ^ Masato Kitamura, Hiromasa Oka, Seiji Suga, and Ryoji Noyori (2004). "Catalytic Enantioselective Addition of Dialkylzincs to Aldehydes Using (2S)-(−)-3-exo-(Dimethylamino)isoborneol [(2S)-DAIB]: (S)-1-Phenyl-1-propanol". Org. Synth.; Coll. Vol. 10: 635. 
  5. ^ Jean-Nicolas Desrosiers, Alexandre Côté, Alessandro A. Boezio, and André B. Charette (2005). "Preparation of Enantiomerically Enriched (1S)-1-Phenylpropan-1-amine Hydrochloride by a Catalytic Addition of Diorganozinc Reagents to Imines". Org. Synth. 83: 5. 
  6. ^ André B. Charette and Hélène Lebel (2004). "(2S,3S)-(+)-(3-Phenylcyclopropyl)methanol". Org. Synth.; Coll. Vol. 10: 613. 
  7. ^ Yoshihiko Ito, Shotaro Fujii, Masashi Nakatuska, Fumio Kawamoto, and Takeo Saegusa (1988). "One-Carbon Ring Expansion of Cycloalkanones to Conjugated Cycloalkenones: 2-Cyclohepten-1-one". Org. Synth.; Coll. Vol. 6: 327. 
  8. ^ Nicholson Baker (2002). Double Fold: Libraries and the Assault on Paper. Vintage. ISBN 0375726217. 
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Diethylzinc". A list of authors is available in Wikipedia.
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