Propargyl bromide

Propargyl bromide, also known as 3-bromo-prop-1-yne, is an organic compound with the chemical formula HC≡CCH₂Br. A colorless liquid, it is a halogenated organic compound consisting of propyne with a bromine substituent on the methyl group. It has a lachrymatory effect, like related compounds. The compound is used as a reagent in organic synthesis.

Applications and production

Propargyl bromide may be produced by the treatment of propargyl alcohol with phosphorus tribromide.

Reactions

Propargyl bromide is an alkylating agent. For example, it reacts with dimethylsulfide, it reacts to give the sulfonium salt:
It alkylates even weakly basic amines such as aniline.
Aldehydes react with propargyl bromide in a Barbier-type reaction to yield alkynyl alcohols:
At low temperatures, upon treatment with magnesium, propargyl bromide gives the Grignard reagent formally derived from allenyl bromide, i.e., CH₂=C=CHMgBr.
Propargyl bromide and its ether derivatives participate in azide-based click reactions.

Safety

Propargyl bromide is a lachrymator and an alkylating agent, This liquid acetylenic endothermic compound may be decomposed by mild shock, and when heated under confinement, it decomposes with explosive violence and may detonate. Addition of 20—30 wt% of toluene makes propargyl bromide insensitive in laboratory impact and confinement tests.