Question

When vinyl & allyl are joined to each other, we get:
A. conjugated alkadiene
B. cumulative alkadiene
C. isolated alkadiene
D. allenes

Answer 1

Hint: A vinyl group is the smallest group containing a vinylic carbon and an allyl group is the smallest group containing allylic carbon. Here, vinylic carbon is the \[s{p^2}\] carbon of an alkene and allylic carbon is the carbon adjacent to a vinylic carbon.

Complete step by step solution:
Allyl is defined as in which functional group is attached to $s{p^3}$ a hybridized carbon atom which is next to the carbon-carbon double bond whereas vinyl is defined as that in which functional group is attached to one of the carbon atoms of the carbon-carbon double bond. when allyl and vinyl are joined together isolated alkadiene is formed. The general reaction for the combination of the vinyl and allyl is shown as:

So, the correct answer is Option C.

Additional information:
One of the allylic compounds, allyl chloride is used to prepare plastics and also involved in the formation of rubber. Whereas Vinyl compounds are used where polymerization polymers are involved and are used to prepare compounds such as Poly Vinyl chloride (PVC). Allylic carbons form stable carbocations and vinylic carbocations are unstable due to the presence of P-character.

Note: The allylic carbon atom is more reactive than normal alkanes and stable carbocations are easily formed when they are adjacent to vinyl carbon. Due to this the electrons get delocalized to stabilize the positive charge. Vinyl groups are directly attached to the molecule and it has two carbon and three hydrogen atoms. Allyl group is attached to the molecule through

group and the general molecular formula for Vinyl is

.