Many are highly flammable, gases are explosive. Chloroacetylene is pyrophoric.

Compared to most hydrocarbons, acetylene is relatively acidic, though it is still much less acidic than water or ethanol. Thus it reacts with strong bases to form acetylide salts. For example, acetylene reacts with sodium amide in liquid ammonia to form sodium acetylide, and with butyllithium in cold THF to give lithium acetylide. Acetylides of heavy metals are easily formed by reaction of acetylene with the metal ions. Several, such as silver acetylide (Ag2C2) and copper acetylide (Cu2C2), are powerful and very dangerous explosives.

The gases are not toxic per se, but can act to exclude oxygen in breathing zone during an incident.

Alkynes (attached hydrogen) have the formulas of H-CC-H or R-CC-H, with R representing any alkyl group such as methyl, ethyl, etc. or halide attached to the carbon. The C-C triple bond makes the adjacent C-H bond more reactive than a typical hydrocarbon C-H bond.

An important application is the conversion of acetylene to ethylene for use in making a variety of polyethylene plastics. An important reaction of acetylene is its combustion, the basis of the acetylene welding technologies. Otherwise, its major applications involve its conversion to acrylic acid derivatives.

1-propyne, acetylene, ethinylestradiol, propargite.