so this next section that we will review uh is devoted to specifically carbocation rearrangements um and you know the method of how to make a determination if a rearrangement will occur so we looked at last time these hydride shifts or methyl shifts and we know that the goal for um a carbocation when it encounters these shifts is to become more stable that way um if we have a methyl carbocation a primary or secondary um they can always uh result in a tertiary or the more stable form that we looked at last time uh if a hydride shift or a metal shift occurs so in this example here we see a secondary carbocation so let's again review how do we determine um is it primary secondary tertiary Etc uh so we look at the carbon that has the positive charge and then we count how many carbons it's bonded to so it's directly bonded to two other carbons so this is how we determine that it is a secondary carbocation so that's our our first step then we look at um with that same molecule right so our cat iic site is given there and um we identify either any hydrogen atoms or methyl groups on a neighboring carbon atom so we see um in green here highlighted the two carbons that we pointed out are directly bonded to our cation and then we expand over here we see this first carbon right carbon one we'll call it has two hydrogens bonded to it and then uh carbon two over here we have a hydrogen or a methyl group so if we were to um move this hydrogen right and do a hydride shift as indicated in uh step two down here we could result in a more stable tertiary carbocation so again we look at the carbon here that has the positive charge and then that's bonded to directly one two three other carbons so we would call this a tertiary carbocation so there are um other instances where if you already have a tertiary carbocation generally you would think that this is uh the most stable out of all the possible carbocations but there is um one instance here that we'll look at uh specifically with what's called an alyc carbocation so if we have an alyc site so that means that next to our um carbocation if a shift occurred um we have this double bond here so resonance can actually um stabilize uh what would already be a stable tertiary carbocation so in this case uh a tertiary carbocation can undergo rearrangement if a more stable alyc carbocation can be formed um so again uh most scenarios you'll see primary secondary uh carbocations rearranging through hydride or methide shifts to form a tertiary carbocation uh more rarely will you see a tertiary carbocation undergo rearrangement to form this ayic carbocation um all right so that's everything for our carbocation rearrangement uh review and we'll continue with the next section uh next time