Hey guys, in Chad's video about this reaction he says that it adds anti-Markovnikov. Once you get to the alkene step, how can you tell which side to add the Br to? Aren't both sides of the alkene equivalent since they each only have one H?
Alkyne reaction with excess HBr and ROOR
- Thread starter TheDanger
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Br is already withdrawing while the other end of the double bond has a methyl that's donating. It technically still adds anti-mark. Yes they both got one H, but you are forced to consider what is different, namely the substituents that stabilize or destabilize the t-state. Adding the H to the more stabilized carbocation accounts for the anti-mark
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No problem. xs hbr/roor isn't typically a problem you encounter.
This is what I was worried about. It seems silly that I'm putting in hours and hours of memorizing every single reaction when I'll only be tested on 2 or 3 of them during the real thing. Any advice on what to focus on? Or is it just completely random for everybody?
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My best advice for getting ochem down as far as "memorizing everything essential" would be synthesis problems and road maps. Don't spend too much time on it, rather split it up over 2-3 days; your mind will get the idea that its more important if it is exposed to the same ideas over consecutive days rather than 2-3 hours for one day. It was all about priority for me. One day, I payed more attention to NMR and pulled out paula bruice; it turned out to be very important that I did that. On separate occasions, I decided to pull out campbell bio and read the immune system and the ch. that had all the meso/ecto/endoderm stuff in it because I found myself missing a lot of questions on them; once again, I am very glad I did that. All of the little tidbits in destroyer bio as well as practice exam Qs made more sense to me because I had locked some knowledge away and had a foundation. Learning is a modification of behavior based on experience. The key was that I was prompted to do so because of the practice problems I encountered. If there is a reaction type you have never encountered and you don't have it down just because Chad mentioned it for 30 seconds in his video, who cares? EX: the alternate reagents with O3 never came up outside of chads and so I just accepted it as fact. If there is a certain type of reaction you are getting wrong, then find a way to fix that first before you worry about things you have never seen in more than one place. You've gotta use your judgement, though, and prioritize what you know you are lacking in. I knew a week out from my exam that I wanted to go through all of my math destroyer problems that I missed one more time because I knew I swept some problem types under the rug; however, I intuitively felt that I needed to watch Chads GC vids and placed it in a higher priority because it is one of the sciences.
