Illustrated Glossary of Organic Chemistry

Acetylide anion (alkyne anion; alkynyl anion): The carbanionic conjugate base of a terminal alkyne, formed by deprotonation of the sp C-H bond (pKa ~25). A good nucleophile and strong base.

General acetylide anion molecular structure.

Alkylation via SN2 reaction.

Nucleophilic addition to an aldehyde gives a propargylic alcohol.