Question

name the three alkenes using systematic names.
a.
the name of compound a is:

Explanation:

Step1: Determine the parent chain

The longest carbon chain containing the double bond has 4 carbon atoms (butene).

Step2: Locate the substituents

There is a methyl group on the second carbon atom.

Step3: Assign the double bond position

The double bond is between the second and third carbon atoms. But in alkenes, when the double bond position is symmetrically placed (as in this case for the parent chain of 4 carbons), we use the lower number for the start of the double - bond. Here, we number the chain from the left (since the methyl group is on the second carbon when numbered from the left, and if we number from the right, the double - bond would start at the second carbon as well, but the methyl group would be on the third carbon. We want the substituent (methyl) to have the lowest possible number). So the name is 2 - methyl - 2 - butene.

Answer:

2 - methyl - 2 - butene