Organozinc compound

Zinc Organic compounds are chemical compounds of zinc with organic radicals. Like many other organometallic compounds, they are reactive and react rapidly with air or water. Organic zinc compounds play as reagents in organic reactions involved, among other things, include the Reformatsky reaction and the Negishi coupling to it.

History

The organozinc dimethylzinc and diethylzinc were the first well-known metal- organic compounds having a σ - bond between the metal and carbon. They were accidentally discovered in 1849 by Edward Frankland, who tried to win from alkyl iodides and zinc radicals. Prior to this discovery organic compounds of semi-metal arsenic and the Zeise's salt were simply known as the first complex with organic ligands.

Production and representation

Organic zinc compounds can be represented in several ways. One possibility is the direct synthesis of metallic zinc, and alkyl iodides with a alkyl zinc iodide unstable intermediate.

Also transmetalation of mercury organic compounds and metathesis reactions with zinc halides and organic lithium or aluminum compounds are possible to represent organic zinc compounds.

Properties

Organic zinc compounds are constructed in contrast to magnesium or berylliumorganischen compounds monomeric. The molecules are linear, bridges, wherein two zinc centers are on a common organic group linked to one another, are not stable. Are possible such two -electron three - center bonds but by hydrogen atoms.

Due to the similar structure by the closed d-shell resemble organic zinc compounds in their chemical behavior of the Grignard reagent. However, they are due to the stronger covalent bond and lower Lewis acidity less reactive than this and therefore react more specific than Grignard reagents.

Use

In the Reformatsky reaction is composed of a α - halogenated carboxylic acid esters and a first organozinc zinc compound which can then act as a nucleophile, a ketone or an aldehyde. In contrast to Grignard reagents, which can undergo similar reactions, the zinc - Reformatski reagent does not react with carboxylic acid esters.

Further reaction, wherein the organic zinc compounds are starting materials, the Negishi coupling. Organozinc reagents and aryl halides react in this reaction under palladium or nickel catalysis together to form a CC bond.

Zinkcarbene in which a carbon- zinc double bond is, play a role in the Simmons-Smith reaction. In this case the carbene is created from first diiodomethane and zinc to react with alkenes to give cyclopropane derivatives.