character of the C–M bond.
1) Alkylsodium and alkylpotassium compounds are highly reactive and are among
the most powerful of bases ⇒ they react explosively with water and burst into
flame when exposed to air.
2) Organomercury and organolead compounds are much less reactive ⇒ they are
often volatile and are stable in air.
i) They are all poisonous and are generally soluble in nonpolar solvents.
ii) Tetraethyllead has been replaced by other antiknock agent such as tert-butyl
methyl ether (TBME).- Organolithium and organomagnesium compounds are of great importance in
organic synthesis.
i) They are relatively stable in ether solutions.
iii) Their C–M bonds have considerable ionic character ⇒ the carbon atom that is
bonded to the metal atom of an organolithium or organomagnesium compound
is a strong base and powerful nucleophile.
12.6 PREPARATION OF ORGANOLITHIUM AND
ORGANOMAGNESIUM COMPOUNDS
12.6A ORGANOLITHIUM COMPOUNDS
- Organolithium compounds are often prepared by the reduction of organic halide
with lithium metal.
- These reductions are usually carried out in ether solvents and care must be taken
to exclude moisture since organolithium compounds are strong bases.
i) Most commonly used solvents are diethyl ether and tetrahydrofuran.
CH 3 CH 2 OCH 2 CH 3 ODiethyl ether Tetrahydrofuran