Alkynes: Physical Properties

The physical properties of alkynes are very similar to those of the alkenes. Alkynes are generally nonpolar molecules with little solubility in polar solvents, such as water. Solubility in nonpolar solvents, such as ether and acetone, is extensive. Like the alkanes and alkenes, alkynes of four or fewer carbon atoms tend to be gases.

Substituted alkynes have small dipole moments due to differences in electronegativity between the triple‐bonded carbon atoms, which are sp hybridized, and the single‐bonded carbon atoms, which are sp 3 hybridized. The sp‐hybridized carbon atom, which possesses more s character than the sp 3‐hybridized carbon atom, is more electronegative in character. The resulting asymmetrical electron distribution in the bond between such carbon atoms results in the generation of a dipole moment.