Alkylation:

One time the alkynide has been created, it can be treated with an alkyl halide to generate more complex alkynes.

Figure:  Reaction of an alkynide ion with an alkyl halide.

This reaction is termed as an alkylation as far as the alkynide is concerned, and is an instance of nucleophilic substitution as far as the alkyl halide is concerned.

Figure: Elimination of HBr.

This reaction acts best with primary alkyl halides. While secondary or tertiary alkyl halides are employed, the alkynide reacts like a base and this result in elimination of hydrogen halide from the alkyl halide to generate an alkene.