Allylic And Vinylic Hydrogens

An allylic hydrogen is a hydrogen atom that is bonded to an allylic carbon in an organic molecule.

Allylic and vinylic hydrogens. A hydrogen atom bonded to an sp 2 carbon of an alkene. Atoms or groups attached to an allylic carbon are termed allylic substituents. Vinyl group vinylic hydrogen vinylic carbocation allylic position benzylic position propargylic position wikipedia entry return to glossary index. Key difference allylic vs vinylic carbons functional groups are very important in understanding the different physical and chemical properties of organic molecules the terms allylic and vinyl carbons indicate whether the carbon atom is bonded directly or indirectly to a double bond in a molecule.

An allylic carbocation in which an allylic carbon bears the positive charge. It contains two sp 2 hybridized carbon atoms and one sp 3 hybridized carbon atom. In other words it is a methylene bridge ch 2 attached to a vinyl group ch ch 2. Allyl form a stable carbocation because of the electron delocalization whereas vinylic carbocations are unstable as they lack p character.

When one hydrogen atom is removed from the third carbon atom of a propane molecule it is equivalent to an allyl group. The key difference between allylic and vinylic carbon is that allylic carbon is the carbon. None of the other hydrogens are vinylic. The libretexts libraries are powered by mindtouch and are supported by the department of education open textbook pilot project the uc davis office of the provost the uc davis library the california state university affordable learning solutions program and merlot.

The organic chemistry tutor 93 912 views. We also acknowledge previous national science foundation support under grant numbers 1246120 1525057 and 1413739. Benzylic position allylic position propargylic position aryl aryl hydrogen. Allyl group holds three carbon atoms and five hydrogen atoms on the other hand vinyl group has two carbon atoms and three hydrogen atoms.

Identify the number of allylic and vinylic hydrogens in the pictured molecules. The vinylic hydrogens are shown in red.