L2 synthesis of RM Flashcards
What are the synthesis routes for RM?
Direct synthesis Transmetallation Metal halogen exchange Metallation Metathesis Addition to C=C bonds
What is the scheme for direct synthesis?
R-X + 2M –> RM + MX
What unwanted reaction can occur during direct synthesis of RM?
Wurtz coupling
What is the wurtz coupling reaction?
Formation of an alkane product
What is direct synthesis route usually limited to?
the use of Li
What is direct synthesis?
The reaction between Alkyl halide and a metal, usually lithium
What is transmetallation?
Transfer of ligands from one metal to another
What is the scheme for transmetallation?
M + RM’ –> RM + M’
What is metal-halogen exhange?
The exchange of ligands between an alkyl metal and an alkyl halide
What is the scheme for metal halogen exchange?
RM + R’X –> R’M + RX
What is halogen metal exchange best for?
R’=Ar complexes with Li
What are the conditions for metal-halogen exchange?
Favoured at low temps
What type of control is metal halogen exchange under?
Kinetic control
What is the addition to C=C bonds reaction?
Double bond opening reaction by the addition of metal ions
What type of reaction is it when a metal ion is added to a C=C bond?
Schlenk dimerisation
What is metathesis?
Reaction in which one part of each compound interchange
What is the general scheme for the metathesis reaction?
RLi + MOR’ –> RM + LiOR’
What is the driving force for the metathesis reaction?
The enthalpy of formation for the lithium alkoxide
What is methathesis useful for?
The synthesis of R-M where M is in group 1
What is metallation?
The attachment of a metal atom to a carbon atom
What does metallation depend on?
Relative acidity of R’H
What is the scheme for metallation?
RM + R’H –> RH + R’M
What is the impact of the addition of a base in metallation?
Activates RM
What is the impact of using TMEDA in metallation?
It deaggregates the R-Li complex which causes a faster reaction
TMEDA donates electron density to Li
