Vinylic Carbocation Definition

A vinylic carbocation which has an empirical formula of c h is a carbocation that has a positive charge only on the alkene carbon atom.

Vinylic carbocation definition.

In the first mechanism step the alkyne is protonated by hydronium ion a strong acid to produce a resonance stabilized secondary vinylic carbocation shown in red. This carbocation is also a benzylic carbocation. The vinyl cation is a carbocation with the positive charge on an alkene carbon. Its empirical formula is c 2h 3.

Carbocation today is defined as any even electron cation that possesses a significant positive charge on the carbon atom. A carbocation is a molecule in which a carbon atom has a positive charge and three bonds. The univalent hydrocarbon group ch 2 ch derived from ethylene. For a positive center to be attached to a more electronegative group is destabilizing.

Look at the figure below notice that in the alkyl carbocation on the left the cationic center is attached to an s p x 3 carbon whereas in the vinylic cation in the middle the cationic center is attached to a more electronegative s p x 2 carbon. In the absence of geometric constraints most substituted vinyl cations carry the formal positive charge on an sp hydridized carbon atom of linear geometry. Formerly it was known as carbonium ion. An allylic carbocation in which an allylic carbon bears the positive charge.

Acid catalyzed hydration of phenyl acetylene a terminal alkyne involves a vinylic carbocation intermediate. An allylic carbon is an sp3 carbon that is adjacent to a vinylic carbon. A carbocation with a two coordinate positive carbon derived from formal removal of a hydride ion h from an alkene is known as a vinyl cation. Any of various compounds containing the vinyl group typically highly reactive easily polymerized and used as basic materials for plastics.