In the first step of the addition reaction with HBr, the pi electrons of the double bond react with the hydrogen ion, H+, produc
ing a carbocation. The hydrogen atom that forms a new carbon-hydrogen bond as a result is highlighted in red. Sort the carbocation intermediates as major carbocations or their corresponding minor intermediates for each of the given reactions. Consider a carbocation minor even if it is highly unstable and may be virtually nonexistant.
In this case, we have to take into account the <u>stability of the carbocations</u>:
Terciary>Secundary>>Primary.
In other words, is we have the <u>most substituted carbocation</u> we will have more stability. Therefore in the carbocation formation, the charge would go in the <u>most substituted carbon</u> of the double bond for each case.