Organo Lithium Reagents (R-Li).

1. Organo Lithium Compounds [R-Li]

• The Bond which is present between the carbon atom of an organic group and the metal lithium is called as organo lithium bond and the compounds are called as organo lithium compounds.

• In organo Lithium compounds the electro negativity of the carbon atom of an organic group is 2.5, while the electro negativity of the metal Li is 0.97.

• In organo Lithium compounds, the electro negativity differences between the carbon atom of an organic group and the metal Li is 2.5 – 0.97 =1.53 is high, results 43% ionization.

• High electro negativity of carbon atom than Li metal negatively polarizes organo lithium bond towards carbon atom of an organic group results in the formation of carbon anion which acts as nucleophile as well as base.

• Due to High ionization of organo lithium metallic bond, the carbon anion which comes is act as strong nucliophile as well as strong base.

• Organo lithium compounds are syntheticall precursors for organo metallic reagents. Since they are used in the preparation of various organo metallic reagents Ex: Gillmann’s reagents.

• Due to High ionization or High polarisability of organo lithium metallic bond, organo lithium compounds (RLi) are more reactive than organo magnesium compounds (R Mg X).

• The reactivity order of organo lithium compounds and organo magnesium compounds is as follows R-Li > R-Mg-X

• Most of the organo ‘Li’ reagent reactions are similar to the reaction of Grignard reagent. But differs in some reactions.