It’s totally on its own and forms the carbocation intermediate. Go down all the various factors and ask yourself how does this help the SN2 backside attack? As opposed to the SN1 mechanism, which is a two-step process, where first the living group just leaves. Or why would a polar aprotic solvent prefer SN2? So the nucleophile attacks the carbon instead of attacking the solvent. ![]() Why would a methyl or a primary carbon favor a backside attack? And that’s because there is less stearic hindrance. Rather than just memorizing, go down the list of all the different factors and figure out why this would favor a backside attack. Just google SN1 versus SN2 and you will find a million charts out there. The nucleophile comes in, attacks the carbon, and kicks off the living group all in a single step. The key to understanding this is starting with the mechanism itself. A Quick Breakdown of SN1 vs SN2 Reactions for the MCAT The right answer here is (D) 2-Chloro-2-Methylpropane because the chloro is on the second carbon and there’s also a methyl group on that second carbon so that’s what we call a tert butyl group in the kind of common nomenclature. ![]() In this case, for SN1, we’re looking for a tertiary or a secondary carbon that would get attacked by the nucleophile. ![]() Remember that a tertiary carbon or a secondary carbon is going to be favored by SN1, whereas a methyl carbon or a primary carbon goes to SN2. Very few of these will show up in the MCAT but by far, the most common is our classic SN1 vs SN2 reactions, nucleophilic substitution both unimolecular and bimolecular. Which of the following alkyl chlorides is most likely to undergo SN1 reaction: Listen to this podcast episode with the player above, or keep reading for the highlights and takeaway points.Ĭlick Here to Download Handout SN1 vs SN2 MCAT Question #1: But even though the mighty has fallen, we can’t ignore this entirely. ![]() It used to comprise 40% of one of the sections of the exam, but now it has been reduced to a lowly 16% of one of four sections. The MCAT has been re-balanced with this new format exam where they really toned down the organic chemistry. Today we’re going to break down some organic chemistry discrete questions, especially focused on SN1 vs SN2 reactions, so you can crush your MCAT!
0 Comments
Leave a Reply. |