Vinylacetylene

Vinylacetylene or butenyne, C4H4, is a highly unsaturated hydrocarbon. It can also be called but-1-en-3-yne, but there is no possible ambiguity. It was discovered in 1959 by Roi Lerner in Hebrew University in Jerusalem. Its boiling point is 3 °C and its melting point is -15 °C.