Hydride Shift vs Methyl Shift - Carbocation Rearrangement

Leah4sci.com/C... presents: Hydride Shift vs Methyl Shift - Carbocation Rearrangement reaction, mechanism, and tricks to easily recognize which shift occurs in alkene and substitution/elimination reactions.
📺Watch Next: Ring Expansion via Hydride and Methyl Shift • Hydride Shift, Ring Ex...
Need help with Orgo? Download my free guide ’10 Secrets to Acing Organic Chemistry’ HERE: leah4sci.com/o...
In this video, you will learn tips and tricks to recognize when a reaction will utilize one of the three common carbocation rearrangements, which include the hydride shift, alkyl or methyl shift and ring expansion. You’ll learn how to draw these carbocation rearrangements in a reaction mechanism and predict the most stable product molecule for a variety of example problems.
You’ll also learn a fun trick to quickly recognize which shift takes place even without having to draw out the mechanism
↪ Links & Resources Mentioned In This Video ↩
▸Carbocation Stability and Ranking Leah4sci.com/C...
▸Ring Expansion via Hydride Shift Leah4sci.com/H...
▸Pencil Trick for Classifying Carbon Atoms Leah4sci.com/P...
▸Alkene Reactions Leah4sci.com/A...
▸Substitution and Elimination Reactions Leah4sci.com/SNE
▸Markovnikov’s Rule in Alkene Addition Reactions Leah4sci.com/M...
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⏱ In this video:
[0:19] Energy Diagram of a Carbocation Rearrangement
[1:07] Carbocation Stability Using the Pencil Trick
[1:49] The Hydride Shift
[4:03] The Alkyl Shift
[5:54] Example: Acid-Catalyzed Hydration of Alkene
[7:14] Example: SN1 Reaction in Acidic Solution
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For more in-depth review including practice problems and explanations, come join my online membership site, the Organic Chemistry Study Hall: leah4sci.com/join
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[@yashkakade9349]

Used to watch your videos during my 11th and 12th grade. Now I'm studying in University. Commenting just because I want to thank you for your work. Your videos really helped me during my JEE prep😁

[@Leah4sci]

Oh wow, so glad my videos were helping you back then. Are you still studying organic chemistry?

[@navyblueskiess]

Did u crack jee

[@triple_gem_shining]

Concise and makes sense! Thanks for not over complicating! Love it.

[@Leah4sci]

Thank you, that's always my goal!

[@abhinavraje3614]

I loves your way of teaching organic chemistry am watching your video when i was preparing for medical entrance exam .now am professional medical College student i watch your videos.

[@Leah4sci]

Thank you so much and congratulations on making it to medical college! I love that my videos are still helping you now as before

[@TarikAbdulla]

Wonderful explanation, in these few minutes you explained everything in a easy way to understand (crystal clear)...

[@Leah4sci]

I'm so glad you found this video helpful

[@theswave7975]

Am in 3rd year at mulungushi doing biochemistry and I just want to thank you for helping me with organic chemistry your are saving me lots of hard work and research 🙏🔥

[@Leah4sci]

You're very welcome

[@perapera68]

YOU EXPLAIN SO WELL THANK YOUUUUU

[@Leah4sci]

Thank you so much! I'm honored and happy to hear the video resonated with you

[@zionpowercontrols7573]

You explain soo good they help me prepare for jee

[@Leah4sci]

Happy to help!

[@VictortheOrganicChemistryTutor]

It's a very nice overview. I love how you always teach through the examples! Oh, and btw, migratory aptitude statement you make is factually incorrect. Smallest group does not migrate the fastest. This topic has been extensively studied since the 60's with the most recent paper (that I know of) published in 2021 by researchers from UC-Davis. And while we cannot make blanket statements about all types of carbocation rearrangements, the general migratory aptitude is H>Ph>3°>2°>1°>Me have been found to be the case over and over again. It "feels" correct to move the smallest group, but it's just not supported by the actual observations. The orbital symmetry rules also do not support the idea of the smallest group migration. So, in your example at 05:27, the isopropyl would have been the correct choice for the alkyl shift.

[@Leah4sci]

Oh wow, this is very interesting, thank you for bringing this to my attention. Just so I understand: The smallest group typically DOESN'T move first, even though this is what all professors do teach (and thus expect students to show on their exams?)

[@VictortheOrganicChemistryTutor]

@@Leah4sci While your sarcasm is palpable here, Leah, it hasn't been my experience in the slightest. And yes, some instructors should've paid more attention in grad school 🤷‍♂ or read the textbook they assign to their students once in a while. In addition to the vast amount of the research literature on the topic, the migratory aptitude is described in many current textbooks, for instance Klein 4th ed. p992 has a full section dedicated to that. We can argue all day long about our anecdotal evidence, but frankly, science doesn't care. And if someone teaches it incorrectly, it doesn't mean we should do the same. In my professional experience, most instructors are perfectly fine to acknowledge when they were wrong about something when presented with evidence contradicting their original statement. However, there are those who seem to perceive constructive feedback as a personal affront. Would you not agree that staying aligned with empirical data is crucial for effective and correct teaching?

[@Elias.04]

@@VictortheOrganicChemistryTutor I don't think Leah's comment sounded sarcastic at all.

[@Leah4sci]

I think you misunderstand my comment / tone. That was not sarcasm. Let me try to clarify 1- I truly appreciate you bringing this to my attention. Given that I don't have an advanced degree in organic chemistry, I only know the information at the level that I studied in undergrad plus whatever research I've done since as I prepare for lessons or recording videos 2- Given this information, I'm wondering if this is something I need to correct FOR my students. My students are studying at the undergraduate level and so I'm wondering if what you shared is something THEY need to be made aware of, OR if their professors are likely to let my explanation slide as mine did back in undergrad. I found your comment helpful and thoughtful, as you took the time to explain this. I try not engage in snark or arguments online

[@VictortheOrganicChemistryTutor]

Thank you for clarifying your earlier comment. Apologies for any misunderstanding about the tone; it's easy for things to get lost in translation online. I'm passionate about evidence-based science, which is why I felt compelled to point out the 'smallest moves first' concept. This notion has a history of being incorrectly taught, even though it may feel intuitively correct. I believe that it's crucial for educators like us to set the record straight. The aim isn't to undermine anyone but to enrich the educational experience for our students. You've done incredible work supporting students' learning journeys, and it's evident that your experience has provided valuable perspectives. My comment was based on my own background, which seems to differ from yours in how this particular topic is covered in classrooms. My main point is simply that the 'smallest moves first' idea is a misconception that I've seen perpetuated by some instructors, and it's something that students should be aware of for future reference. Keep up the great work, and thank you for taking my comments to heart!

[@Steph042]

I’m new to your videos and I love u ❤️ THANK YOU

[@Leah4sci]

So glad that you are here and thanks so much!!!

[@paulmusumpuka2053]

Perfect, Now I want to know how an alkene can form a primary alcohol, thanks for the video 🙏🫂

[@Leah4sci]

I cover hydroboration in my alkene reaction series leah4sci.com/alkene

[@paulmusumpuka2053]

@@Leah4sci thank you so much 🙏

[@Leah4sci]

You're very welcome

[@MariamMohamed-kk2nd]

Thank you for the nice video. If it could be possible please provide a video of the reaction of an alkene with more than one double bond to form a carbene.

[@Leah4sci]

I don't have a video on that specific reaction but I do cover carbenes here: kzbin.info/www/bejne/jaTcc6CwaaqHqa8 hope it helps

[@anuragtewary5314]

Hi. I have been watching some of your videos on varied topics and i find them really helpful for my course. It'd be really amazing if youd make a discord community for students to discuss doubts

[@Leah4sci]

So glad to hear that my videos are helping. I actually do have a community where you can ask questions and discuss what you're studying. Details here: leah4sci.com/join

[@abismalcj1164]

Wow thank you very much❤

[@Leah4sci]

You're very welcome!

[@psycheqg6294]

Thanks again.

[@Leah4sci]

You're very welcome

[@chrise27]

thank you

[@Leah4sci]

You're welcome!

[@triple_gem_shining]

Awesome

[@Leah4sci]

:)

[@Rishabh_0749]

Ma'am please make videon on ethers, aldehydes and ketone for graduation students 😊😊

[@Leah4sci]

Thanks for the recommendation. I post free videos that cover undergraduate Orgo topics as I have time, but I'm always looking for suggestions.

[@Rishabh_0749]

@@Leah4sci yeah ma'am.totally 👍 agree.

[@sweet-Inorganic-Chemistry]

Perfect

[@Leah4sci]

Thanks

[@שירה-י9מ]

hi! will a methyl shift occurs between a tertiary carbocation and a 4 substituted carbon? another question - will a hydride shift occurs between two tertiary carbocation ? thank you!!

[@Leah4sci]

The most stable carbocation is a tertiary carbocation and so there would be no value in shifting a methyl to a tertiary position, same with H

[@nikhilverma9398]

One degree carbocation near three degree carbocation will hydride shift occur or not

[@Leah4sci]

If you have a primary carbocation next to a tertiary carbon, then yes. The hydrogen from the tertiary position would shift over to the primary position, so that we ultimately have a more stable tertiary carbocation. For more on carbocation stability, make sure to see my tutorial at Leah4sci.com/carbocation

[@asianduh8108]

3:40 if the positive charge was at the furthest carbon, could 2 hydride shifts occur? one so the positive charge moves from the right-most carbon to the second right-most carbon, and then another hydride shift as shown in the video?

[@Leah4sci]

Good question! The answer is no, because you can only shift the carbocation to the next position. That means only one position over, left or right. Whether you visualize your proposed situation happening in one or two steps doesn't matter. You simply cannot move a carbocation over two positions. It is not energetically favorable.

[@kafulakaluba6051]

Thank you so much 💗

[@Leah4sci]

You are so welcome