I know that benzene is an alkene, but what is Isopropylbenzene -- C9H12 ?

yes. IT is a cycloalkene.

The trivial name for isopropylbenzene is cumene. It is a substituted benzene.

Therefore cumene is an alkene?

Since benzene is an arene, I would call it that (an arene). Technically, it is an alkene but usually aromatic hydrocarbons are called arenes to distinguish them from their cousins, the straight chain alkenes. And I suspect an organic chemist would fuss at me for even calling them cousins.

Actually, benzene is not an alkene but a type of cyclic hydrocarbon known as an aromatic compound. It has a specific molecular structure consisting of a six-carbon ring with alternating double and single bonds between the carbon atoms.

Now, let's talk about isopropylbenzene, which is also known as cumene. Its chemical formula is C9H12, which means it contains 9 carbon atoms and 12 hydrogen atoms. The structure of isopropylbenzene consists of a benzene ring with an isopropyl group (-CH(CH3)2) attached to it.

To understand the structure of isopropylbenzene, you can start by picturing the benzene ring, which has six carbon atoms in a cyclic arrangement. Then, imagine replacing one of the hydrogen atoms in the benzene ring with an isopropyl group, which is a branch consisting of three carbon atoms and one methyl group (-CH3).

By following this process, you can visualize the structure of isopropylbenzene or cumene, which is a common compound used in the production of phenol and its derivatives.