Note: HBr addition with Markovnikov regioselectivity based on carbocation intermediate preference for carbocation at the more highly substituted carbon

Caution: Carbocation intermediates can undergo rearrangements, such as the hydride shift in this example

Note: Benzylic (and allylic) carbocations are relatively stable, conferring the regioselectivity in this reaction

Note: Carbocation intermediate is achiral (planar), thus yielding both enantiomer products

Note: Again, achiral carbocation intermediate yields both enantiomer products, regardless of starting material chirality

Note: HBr adds to alkyne π bonds similar to alkene addition with respective Markovnikov regioselectivity for terminal alkynes

Note: Allylic carbocation intermediates have alternative resonance structures, resulting in the possibility of 1,4 additions beyond the "usual" 1,2 addition

Note: In contrast to 'base driven' epoxide opening like with organometallics, acid-catalyzed epoxide opening prefers the nucleophile (Br- in this case) to attack the more substituted site based on partial carbocation character

Note: Acid-catalyzed halide substitution (Sn2) of hydroxyl group.

Note: Acid-catalyzed halide substitution (Sn1) of hydroxyl group.

Caution: Acid-catalyzed halide substitution by Sn1 mechanism is susceptible to carbocation rearrangements

Note: Acid-catalyzed epoxide opening. Note regioselective preference for more substituted side. Similar to Sn1/E1 selectivity, but no actual carbocation formed, thus still stereospecific