Chapter 12.3, Problem 12.13P

Interpretation Introduction

Interpretation:

The reagents necessary to achieve the given transformation has to be identified.

Concept Introduction:

Alkynes are the compounds that contain a triple bond between two carbon atoms.  The carbon atom present in the triple bond is $sp$ hybridised.  Due to this, the geometry of alkyne will be linear.  Terminal alkyne are the one which has a proton attached to the triple bond and internal alkyne are the one in which there are no protons attached to the triple bond.

The terminal alkynes can be deprotonated upon treatment with a strong base such as sodium amide to give an alkynide ion.  Alkynide ions are very strong nucleophiles and can take part in ${\text{S}}_{\text{N}}\text{2}$ reaction, when treated with electrophile.  The electrophile may be only primary halide because elimination reaction will be favored in case of secondary and tertiary halide.

If the starting alkyne is acetylene, then the installation of the alkyl groups has to be done one at one time.  This means that one group is installed on one side and then the second substitution takes place in next step.