Question: What alkylborane is formed from hydroboration of each alkene?

When there is a double bond in the compound, and the priority groups are present on the different sides of adjacent carbon, it is called E-configuration.

a. The given compound has six carbon atoms in a chain in which the double is present at the C-2 atom. The priority groups are present on different sides of the double bond. Thus, it has E-configuration.

Methyl groups are attached to C-3 and C-5 atoms. The IUPAC name of the given compound is shown below:

(E)-3,5-dimethylhex-2-ene

b. The given compound has five carbon atoms in a cyclic form in which the double is present at C-1 atom. At C-1 atom, the sec-butyl group is attached, and at C-2, the methyl group is attached.

The IUPAC name of the given compound is shown below:

1-sec-butyl-2-methylcyclopent-1-ene