Final answer:
HX addition reactions where rearrangements are possible produce rearranged carbocations that can lead to products derived from these more stable intermediates.
Step-by-step explanation:
In cases where rearrangements are possible, HX additions typically produce carbocations that can rearrange to form more stable intermediates. These intermediates can then react further, leading to the formation of products that might be different from the expected addition product if no rearrangement occurred.
For example, during the hydrohalogenation of an alkene, a carbocation intermediate might undergo a 1,2-hydride shift or 1,2-methyl shift resulting in a rearranged more stable carbocation before the halide ion adds to it. The outcome can include products derived from these rearranged carbocations, often leading to the major product being the result of the most stable (tertiary) carbocation.