The reaction of acetylide anion and chloromethane:
The acetylide anion has strong localization of negative charge at its terminal
carbon (indicated by red in the electrostatic potential map).
Chloromethane has partial positive charge at the carbon bonded to the
electronegative chlorine atom.
The acetylide anion acting as a Lewis base is attracted to the partially positive
carbon of the 1° alkyl halide.
Assuming a collision between the two occurs with the proper orientation and
sufficient kinetic energy, as the acetylide anion brings two electrons to the alkyl
halide to form a new bond and it will displace the halogen from the alkyl halide.
The halogen leaves as an anion with the pair of electrons that formerly bonded it
to the carbon.
4.20 AN INTRODUCTION TO ORGANIC SYNTHESIS
Organic synthesis is the process of building organic molecules from simpler
precursors.
Purposes for organic synthesis:
For developing new drugs ⇒ to discover molecules with structural attributes that
enhance certain medical effects or reduce undesired side effects ⇒ e.g. Crixivan
(an HIV protease inhibito, Chapter 2).
For mechanistic studies ⇒ to test some hypothesis about a reaction mechanism
or about how a certain organism metabolizes a compound ⇒ often need to
synthesize a particularly “labeled” compound (with deuterium, tritium, or^13 C).
The total synthesis of vitamin B 12 is a monumental synthetic work published by R.
B. Woodward (Harvard) and A. Eschenmoser (Swiss Federal Institute of
Technology):
