I read my textbooks reaction mechanism chapters from start to finish and didn’t find anything about it! You could then imagine my disappointment when I saw a question similar on my practice exam.
I watch your one of your videos every night before I go to sleep. Very enjoyable, no pressure, easy to understand. I choose to watch the video that's related to the material I study on that day. I don't have to worry about ochem exams anymore. Truly appreciate your work!
Simple explanation, awesome. I have an amazing professor but he's a Harvard double grad genius who's so smart he doesn't realize he lectures extremely quickly. The ring alkyl shift had me perplexed this whole time but now it's obvious, thanks!
Finally a tutorial which actually helped me. Everyone was just skipping over the most confusing part - where the carbocation was supposed to be placed after ring formation.
Very nice 👌👍👏 explaination mam I was pretty confused in this topic before watching 👀 this. Now I have understood. Thanks from a neet aspirant from 🇮🇳🇮🇳
Amazing explanation. I just have one question. At 2:22, you chose to break that bond to shift it over. What if you chose the right side of the cyclo butane. When I tried doing this myself, I got 1,3-dimethylcyclopentan-1-ol. I am not too sure if we can do it like this though. Did you arbitrarily pick that bond of the cyclobutane? Thank you!
Yes, it was an arbitrary decision to break the bond on the left. The situation that you have laid out is a viable alternative to the mechanism in this video. It is very likely that the product mixture of this particular reaction would contain a large percentage of 1,3-dimethylcyclopentan-1-ol.
@@Leah4sci The embedded video would have done that by nature. It would simply have brought the individual back here. But I've decided not to write the piece.
Amazing explanation ma'am. I have a doubt can u please help me out " If a carbocation have two possibilities one is rearrangement and 2nd is internal ring attack,what would happen " eg. If 1-chloro-2-methyl-4-(meta-toluine) butane +AlCl3 ------> what's the final product , please please if possible answer my doubt 🥺🥺🥺 , waiting
I'm sorry, but I don't offer tutoring over social media. For help with questions like this and more, I recommend joining the organic chemistry study hall. Details: leah4sci.com/join or contact me through my website leah4sci.com/contact/
Glad it helped! Yes, it is definitely possible to have an alkyl shift. The mechanism for this is explained here: ruclips.net/video/cSW9LDxtuoA/видео.html
my question is : you choose to break the bond above to do the shift but what if I choose to break the one underneath -H ( red pause 2:25), will i get the same product? i've tried it but it i don't get the same :(
probably wayy too late; i tried what you said, and i get the same product ( my product is just flipped over, makes no difference however ). Nice question however ^^
a very good expanation of the concept! Amazing teacher! do u hve a video on sn1 , sn2 and neighbouring group participation(NGP) substituion reactions??
That's a great question! In actuality, either bond can break, leading to a mixture of possible products. My RUclips videos are only brief overviews of these concepts. For in depth help with questions like this and more, I recommend joining the organic chemistry study hall. Details: leah4sci.com/join or contact me through my website leah4sci.com/contact/
You're very welcome! Ring expansion is favorable when it produces a more stable, 5- or 6-membered ring. Remember that 6-membered rings are THE most stable and “happy” cyclic structures. 5-membered rings are also preferable to smaller ones.
Medam,please help me, if adjacent carbon of carbocation contain two methyl groups and one phenyl group then which will shift first? Why? And if this carbon contain two phenyl groups and one methyl then which will shift first,why? Which is true order ? Hydride>phenyl>alkyl Or Hydride>alkyl>phenyl?
I'm sorry, but I don't offer tutoring over social media. For help with questions like this and more, I recommend joining the organic chemistry study hall. Details: leah4sci.com/join or contact me through my website leah4sci.com/contact/
Yes, tertiary carbocations are more stable than secondary. That is exactly why the tertiary one is present when the water molecule comes in to attack. It is so stable that the hydride shift happens almost instantaneously in this reaction to produce the more stable tertiary intermediate (rather than having the secondary carbocation persist).
If you’re speaking of the decision to expand the ring, it was MORE preferable for the alkyl shift (ring expansion) to proceed because of the large increase in stability that a 5-membered ring provides. The hydride shift to form a tertiary carbocation on the cyclobutane does not happen in place of the ring expansion.
I had one qn like this during my test and I screw up in it.( which is worth like a lot of marks) but Thanks to yur video, I now understand hw to tackle such qns. Even though its kind of late for my test but its good for my final exam. :)
I'm sorry, but I don't offer tutoring over social media. If you ever find you need help with questions like this again, I recommend joining the organic chemistry study hall. Details: leah4sci.com/join or contact me through my website leah4sci.com/contact/
great video .... and ..can there be two ring expansions in any possible way could the cyclopentane ring expand to cyclohexane cuz cyclohexane is the most stable acc. to baeyer's strain theory
according to buyers strain theory, six membered ring is more stable so 7 membered ring will undergo contraction to 6 membered ring and by the way a 4 membered ring will convert to 5 membered ring only and similarly a 5 membered to 6
can this allow a primary carbocation to form, i just got a ring expansion question on an org exam but the leaving group was attached to a primary carbon. It's been a mantra throughout the course that primary carbocations are too unstable and dont form, so it dosnt make any sense
I'm sorry, but I don't offer tutoring over social media . For help with questions like this and more, I recommend joining the organic chemistry study hall. Details: leah4sci.com/join or contact me through my website leah4sci.com/contact/
ring strain is proportional to the angles in the the cycloalkane. as she mentioned in the video, the carbons are most stable when they form angles around 109.5. going from a square to a pentagon actually reduces the angles at every coroner and thus the strain. it can be a little unclear to think about a square vs. a pentane. instead, picture a cyclopropane, which would be a triangle. now compare that to a square. which one has tighter angles? the triangle. thus more strain.
If you look on top of and below the reaction arrow, you'll see that the reagents in this reaction are an acid in water. When a strong acid is placed in water, it completely dissociates to form the hydronium ion, which is H3O+. I've rewritten that to H-OH2+, so that you can visualize the proton that is being attacked.
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why do so many o.chem books leave out the ring expansion topic when they teach alkene mechanisms? Thumbs Up Ms. Fisch! Thanks for the explanation.
Literally every book man, I couldn't find this anywhere, not even clayden.
I read my textbooks reaction mechanism chapters from start to finish and didn’t find anything about it! You could then imagine my disappointment when I saw a question similar on my practice exam.
so they can screw you in the exam
So happy I could help!
Ah... Finally the rearrangement makes sense. Very succinctly explained. Thanks
Woohoo!!! So glad to help clear it up for you!
I watch your one of your videos every night before I go to sleep. Very enjoyable, no pressure, easy to understand. I choose to watch the video that's related to the material I study on that day. I don't have to worry about ochem exams anymore. Truly appreciate your work!
Oh wow, that's awesome to hear, thank you!
An amazingly clear explanation! You're a phenomenal teacher! Thank you! :)
You're very welcome! Glad it helped!
Thank you sooooo much Leah! You're literally a life saver! So happy I found you:)
Awww you're so welcome!
Simple explanation, awesome. I have an amazing professor but he's a Harvard double grad genius who's so smart he doesn't realize he lectures extremely quickly. The ring alkyl shift had me perplexed this whole time but now it's obvious, thanks!
Yes, that's common for people that are so intelligent. Sometimes they don't know how to break it down enough. Glad I could help!
Finally a tutorial which actually helped me. Everyone was just skipping over the most confusing part - where the carbocation was supposed to be placed after ring formation.
Happy to help!
Very nice 👌👍👏 explaination mam I was pretty confused in this topic before watching 👀 this. Now I have understood.
Thanks from a neet aspirant from 🇮🇳🇮🇳
Glad to hear that! you're so welcome!
@Naveen praveen yes
Amazing explanation. I just have one question. At 2:22, you chose to break that bond to shift it over. What if you chose the right side of the cyclo butane. When I tried doing this myself, I got 1,3-dimethylcyclopentan-1-ol. I am not too sure if we can do it like this though. Did you arbitrarily pick that bond of the cyclobutane? Thank you!
Not really sure but ........ the bond on the left is broken may be because it's more unstable due to the alkyl grp connected to it .
Yes, it was an arbitrary decision to break the bond on the left. The situation that you have laid out is a viable alternative to the mechanism in this video. It is very likely that the product mixture of this particular reaction would contain a large percentage of 1,3-dimethylcyclopentan-1-ol.
Absolutely simple and easy to understand , please be encouraged to make more of these.
Glad you enjoyed it!
Thank you for explaining this so clearly! The ring expansion was driving me nuts!
You are very welcome!
My gosh! This was awesome--Thank you!
You're so welcome!
LEAH YOU ARE JUST AMAZING AT THIS EXPANSION EXPLANATION. GOOD JOB KEEP IT UP.!!!!!
Thanks for your kind words. I'm glad you like it!
Thank you so much. I now have an idea through your tutorial. You are an amazing teacher!
You're so very welcome, happy to help!
Nice work you diserve nobel award from ethiopia 👏👏🇪🇹🇪🇹🇪🇹
Awww, thanks!
Extremely thorough and helpful, thank you !!
You're very welcome!
Excellent. You have been and also be the best at what you do.
Thank you so much. I appreciate the compliment!
I liked it. I am a retired chemist and really enjoyed your presentation. I intend to embed it in a simple article I've written.
Sure thing, just make sure to site the source!
@@Leah4sci The embedded video would have done that by nature. It would simply have brought the individual back here. But I've decided not to write the piece.
Thank you so much to understand the rearrangements in carbocations in easyway
You are welcome!
Amazing mam...iam from India and I had problem with such kind of mechanism....ur explanation was magnificent....
Aww, thanks for your kind words!
Thank you so much I had a ring contraction problem and this was the only thing I could find to help me solve it
Glad I could help!
THANKS I LOVE YOU YOU'RE A LIFE SAVER 💞💞💞💞💞💞💞
Aww you're so welcome!
Thanks a lot for clearing my concepts.
You're so very welcome, happy to clear it up!
Oh.. Thank you mam... I'm searching for a long time to get a clear answer for this
Glad you found your answer! You're welcome! :)
Amazing explanation ma'am.
I have a doubt can u please help me out
" If a carbocation have two possibilities one is rearrangement and 2nd is internal ring attack,what would happen " eg. If 1-chloro-2-methyl-4-(meta-toluine) butane +AlCl3 ------> what's the final product , please please if possible answer my doubt 🥺🥺🥺 , waiting
Maybe IUPAC of compund I had written was incorrect it can be " 1-chloro-2-methyl 4-(3-methyl phenyl) butane " maybe it's correct IUPAC
I'm sorry, but I don't offer tutoring over social media. For help with questions like this and more, I recommend joining the organic chemistry study hall. Details: leah4sci.com/join or contact me through my website leah4sci.com/contact/
Question: can we have 2 ring expansion product depending if there is a bond between left or right carbon and if so what is major ?
Yes, that would be an option, as for major... I don't know as this would have to be measured in a lab
Thanks so much, it really helped!
You're so welcome!
You save my chemistry!Thanks a lot. Student from Taiwan.
Happy to help!
This really helped me alot! But from that example , is it possible to have an alkyl shift?? If yes, could you upload a video for that?
Glad it helped! Yes, it is definitely possible to have an alkyl shift. The mechanism for this is explained here: ruclips.net/video/cSW9LDxtuoA/видео.html
OMG!!!! this helped sooo much! Thanks for the video!
You're very welcome
Thank you so much Ma'am!
You are so welcome!
Could not understand ring expansion earlier...Not anymore... Big thanx to u 😊😊
Glad I could help!
can we do a hydride / methyl shift followed by ring expansion
bcas i was taught that u cannot do 2 carbocation rearrangement in a single mechanism
SOOOO much helpful. Thanks!
Glad it was helpful!
my question is : you choose to break the bond above to do the shift but what if I choose to break the one underneath -H ( red pause 2:25), will i get the same product? i've tried it but it i don't get the same :(
probably wayy too late; i tried what you said, and i get the same product ( my product is just flipped over, makes no difference however ). Nice question however ^^
It didn't occur to me. Yes you're right, we have the potential for a constitutional isomer
Thank you so much, you are a great teacher.
You're very welcome!
thank you maam.With My competitive exams approaching, this doubt clearing was essential
You're welcome. All the best on your exams! :)
This helped me so much, Thank you!
You are welcome!
this helped SO much, thanks!
You're very welcome, happy to help!
this helps by a lot
Glad it helped you!
a very good expanation of the concept! Amazing teacher!
do u hve a video on sn1 , sn2 and neighbouring group participation(NGP) substituion reactions??
Glad to help! You can find all of my resources here: leah4sci.com/syllabus
Thanks a lot mam for making it easier
You're very welcome 😊
just loving you, thksss a lot from Brazil
You're welcome!
Loved it!!!! 😍
Awesome!!!
wow..thanks ..i always had difficulties with this..thxx a lott...n keep uploading...any suggestion for a good book on organic chemistry..
You are so very welcome, happy to help! And you can find my top pics for orgo here: leah4sci.com/5-must-have-organic-chemistry-resources/
Thanks for that great video
You're welcome!
THANK YOU SOOOOO SOOOO SOOOO MUCH!!!!!
You're so very welcome, happy to help!
Awesome video. Thank you very much.
You're welcome!
Very good explanation ...
Glad you like it!
THANK YOU
You're welcome :)
Really it's osm explanation...love from India 🤗🇮🇳🇮🇳
Glad it helps!
Thanks a lot ma'am.
You're welcome 😊
Exactly my doubt! thanks a lot ;)
You're so welcome!
Thanks for the video
You're welcome!
Outstanding explaination
Glad you enjoyed it!
Thank you so much
you're so welcome
From the structure, it seems like carbocation should be on C1. How do we know it's on C5 after the ring expansion?
Look at which carbon lost a bond and got nothing back in return
Thanks Leah you da man
You're welcome!
Why doesn't the bond on the right of the square break instead of the top of the square? How do you know which bond will break?
That's a great question! In actuality, either bond can break, leading to a mixture of possible products. My RUclips videos are only brief overviews of these concepts. For in depth help with questions like this and more, I recommend joining the organic chemistry study hall.
Details: leah4sci.com/join or contact me through my website leah4sci.com/contact/
IT ALL MAKES SENSE NOW
Awesome!!!!
Thanks again!! :)
You're so welcome!
that was amazing thanks a lot ! :)
You're very welcome!
thank u so much ...very helpful
You're very welcome!
I understand what you did but there is a something I did not get it that HOW CAN I KNOW WHEN I SHOULD EXPAND THE RİNG??? THANK YOU SO MUCH!!
You're very welcome!
Ring expansion is favorable when it produces a more stable, 5- or 6-membered ring. Remember that 6-membered rings are THE most stable and “happy” cyclic structures. 5-membered rings are also preferable to smaller ones.
Thanks cleared my concept
So happy to help!
Nyc explanation maam...😌😄
Thanks a lot 😊
@@Leah4sci ᴡʟᴄᴍ ᴍᴀᴀᴍ yᴏᴜ ᴅᴇꜱᴇʀᴠᴇ ᴛʜɪꜱ 😄
Medam,please help me, if adjacent carbon of carbocation contain two methyl groups and one phenyl group then which will shift first? Why? And if this carbon contain two phenyl groups and one methyl then which will shift first,why?
Which is true order ? Hydride>phenyl>alkyl
Or
Hydride>alkyl>phenyl?
I'm sorry, but I don't offer tutoring over social media. For help with questions like this and more, I recommend joining the organic chemistry study hall. Details: leah4sci.com/join or contact me through my website leah4sci.com/contact/
awesome and simple
You are very welcome!
Why did oh- attack tertiary carbonation and not secondary. Isn't tert carbonation more stable?
Yes, tertiary carbocations are more stable than secondary. That is exactly why the tertiary one is present when the water molecule comes in to attack. It is so stable that the hydride shift happens almost instantaneously in this reaction to produce the more stable tertiary intermediate (rather than having the secondary carbocation persist).
huggggggggggggggggggggg*
thanks you!!!!
helped me a lot!!
You're very welcome!
Omg this is so fun! I want to solve more of these can someone tell me where will I get such problems?
Awesome! Glad you love it!
@@Leah4sci all thanks to you
Thank u so much
You're very welcome!
What would happen if we did do a hydride shift earlier for the last problem?
If you’re speaking of the decision to expand the ring, it was MORE preferable for the alkyl shift (ring expansion) to proceed because of the large increase in stability that a 5-membered ring provides. The hydride shift to form a tertiary carbocation on the cyclobutane does not happen in place of the ring expansion.
Thank you!
You're very welcome!
Nice explanation
Glad it helped!
I had one qn like this during my test and I screw up in it.( which is worth like a lot of marks) but Thanks to yur video, I now understand hw to tackle such qns. Even though its kind of late for my test but its good for my final exam. :)
I'm so glad I was able to help you understand this for your final!
Thank you so much!!!!
You are so welcome!
i love you
thanks
Very good 😊
Thanks for watching!
Why the other C-C bond didn't break in the 2nd step during ring expansion?
I'm sorry, but I don't offer tutoring over social media. If you ever find you need help with questions like this again, I recommend joining the organic chemistry study hall. Details: leah4sci.com/join or contact me through my website leah4sci.com/contact/
Do you have any videos on Alkynes reactions?
You can find that and more using my free syllabus guide: leah4sci.com/syllabus
How do you know when you substitute with hydrogen or make a ring expansion ?
If you have the option to create a more stable ring, ideally 6 C from 5 or 7, you'll get a ring expansion or contraction
My mind.....wow!
Thank you!
helpful !!!
Great!
At 3:15 why not shift the carbocation to make way for a six membered group?
That is exactly what happens in the next step as I teach just a few minutes later
great video .... and ..can there be two ring expansions in any possible way could the cyclopentane ring expand to cyclohexane cuz cyclohexane is the most stable acc. to baeyer's strain theory
according to buyers strain theory, six membered ring is more stable so 7 membered ring will undergo contraction to 6 membered ring and by the way a 4 membered ring will convert to 5 membered ring only and similarly a 5 membered to 6
+v sai rahul vaddadi sorry bayers
Thank you! As the other comments already said, six is ideal
thanks a ton..!!!!
You're welcome!
can this allow a primary carbocation to form, i just got a ring expansion question on an org exam but the leaving group was attached to a primary carbon. It's been a mantra throughout the course that primary carbocations are too unstable and dont form, so it dosnt make any sense
Primary carbocations should NOT form without resonance to stabilize the charge
In one compound 2 times ring expansion is possible or not?????
I'm sorry, but I don't offer tutoring over social media . For help with questions like this and more, I recommend joining the organic chemistry study hall. Details: leah4sci.com/join or contact me through my website leah4sci.com/contact/
respect !!
thanks!
I love you!!
Thanks!
Very nice! Thank you. *subscribes*
You're very welcome and thanks for subscribing!
awesome
Thank you!
but wait....doesn't the ring the strain increase when it changes from a squared shaped to a pentagon?
At which point in the video?
ring strain is proportional to the angles in the the cycloalkane. as she mentioned in the video, the carbons are most stable when they form angles around 109.5. going from a square to a pentagon actually reduces the angles at every coroner and thus the strain.
it can be a little unclear to think about a square vs. a pentane. instead, picture a cyclopropane, which would be a triangle. now compare that to a square. which one has tighter angles? the triangle. thus more strain.
Nice one...
Glad you liked it
Wow! Well appreciated! #2019
Glad I could help!
ring opening
What about it?
errr where the heck do does the h-oh2 come from?
If you look on top of and below the reaction arrow, you'll see that the reagents in this reaction are an acid in water. When a strong acid is placed in water, it completely dissociates to form the hydronium ion, which is H3O+. I've rewritten that to H-OH2+, so that you can visualize the proton that is being attacked.
ah got it. thank you!!!@@Leah4sci
As am the only one who stumbled upon this on my RUclips feed. I know nothing about this subject 😹
Welcome! Glad you found it!
@@Leah4sci ik it's to much to ask but what's this subject all about and can it be applied to my day life and how
IS 1ST ONE FOLLOWS MARKONIKOVS RULE ??
Markovnikov's rule is for pi bonds