Another clue is that E2 rxn will always include heat. Any reaction done in a turtbutoxide is also usually E2 . The formation of the Tertiary groups in an SN2 reaction crowd the electrophile and don't allow the nucleophile to come in but it can still be possible for E2
Hey, I just wanted to thank you for your videos. Because of watching them, amongst following a lot of other study habits, I was able to get an A in Ochem 1. *Cheers inside.* :)
Beautiful video! I think the concept of stereochemistry inversion should have been brought up using chiral examples, but it was really informative regardless.
Very grateful for your videos! My professor reads from the book during lectures so your videos are a tremendous help. Thank you for sharing your talent and knowledge!
This is such a cool idea and great video! I'm a chemistry prof in the US working on a similar approach on my channel. I like breaking down the concepts by videos, and giving an introduction to a topic (e.g., Assigning R/S stereochemistry) in 5 min or less!
My final is in five days. My prof never taught us any mechanisms - just to memorize the reactions. I want a refund. Thanks Leah!! I've sent my classmates to your channel.
See the E1 and E2 videos in this series and let me know if you still don't understand after watching them all leah4sci.com/nucleophilic-substitution-and-beta-elimination-sn1-sn2-e1-e2-reactions/
This is a complicated question. With all else being EQUAL, heat will favor an elimination reaction over substitution. But there's always a lot to take into account when choosing between SN/E reactions. 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/
The dehydrobromination of isopropyl bromide requires several hours of reflux with alcohol KOH whereas in t.BuO-K+ / DMSO, dehydrobromination can be carried out in less than a minute at room temperature. Why this is so?
Potassium tert-butoxide is a large, bulky base and is favored for elimination reactions because it cannot approach the carbon closely enough to react in a substitution. KOH, on the other hand, is much less sterically hindered and, without reflux at increased temperature, could react with the halide in a substitution reaction to produce a secondary alcohol.
Increasing reaction temperature shows favor to elimination reactions over substitution. The explanation for this comes down to a discussion of the Gibb’s free energy values for elimination reactions being lower (more spontaneous) at high temperatures. The inverse of that is the Gibb’s free energy for substitution reactions is lower (more spontaneous) at low temperatures. Hope this helps!
Good question! The ability for chlorine to leave the carbon atom is based on several factors, including the stability of the carbocation intermediate, the stability of the anion formed, and the type of solvent used. When the halide does choose to leave the carbon atom, it is attracted to (and solvated by) the polar solvent that is favored by SN1 reactions. So you can think of it in that way: it leaves because its attraction to the solvent is greater than its attraction to the carbon of the carbocation.
No, we determine the degree of substitution by identifying the number of carbons directly attached to the carbon in question, not the number of hydrogens. The carbon on the right of the Cl would be primary, while the carbon on the left is considered secondary. See my pencil trick to learn more: leah4sci.com/pencil-trick
00:38 Are we gonna ignore the fact that you have a strong acid (H⊕) as one of your reagents? :q This means that someone should get protonated before anything else could happen. The only candidate for protonation here is the alcohol, but once it gets protonated, it won't possibly be able to act as a nucleophile. Before protonation, it was a weak nucleophile at most. After protonation, it would be even worse, because of the positive charge it would get. And this positive charge would make it keep away from the also positive carbocation. So besides protonating the alcohol, I don't think that you'll get any SN1 reaction here. Another problem with this acid is this: _which_ acid in particular? In these type of reactions, solvents are very important, so you must be specific, because depending on the acid, there might be a different result. If you used hydrochloric acid, I don't think that the chlorine from the tert-butyl chroride would be so eager to leave the molecule, considering that this would increase the amount of chloride ions in the solution, and Mr. le Châtelier might frown upon it :q The acid actually seems to be driving the reaction in the opposite direction, making the molecule more stable as it is. The fact that you got negative charges on stuff in an acid-catalyzed reaction should already blink some red lights. Because acids tend to get rid of negative charges as soon as they appear, or don't let them appear in the first place. And the fact that you started with an acid catalyst and didn't regenerate it at the end, is also kinda sus. And lastly: why an acid at all? The alcohol can act as a nucleophile as it is (definitely better than if you protonated it). Sure, it is a weak nucleophile, but still a nucleophile, and it can attack a strong nucleophile (such as the carbocation left beind the chloride as it leaves the molecule) just fine. It is also a polar protic solvent on its own, favoring the SN1 reaction. BonBonus point: atoms can't just fall off "on their own". That would be very unfortunate for chemistry and stability of matter in general :q And they can't just "choose to leave" (regarding your reply to someone else), because atoms are not persons, they don't have their own mind and they cannot "choose" anything. They can be _made_ to leave by some external factors (in this case, the solvent).
@@Leah4sci Yeah, right… So that you could advertise some more of your tutoring sessions? :q I'm well accustomed with your canned replies here, and as I already said I'm not really interested, I don't need tutoring. And this wasn't really a question. More like a critique. But whatever…
Another clue is that E2 rxn will always include heat. Any reaction done in a turtbutoxide is also usually E2 . The formation of the Tertiary groups in an SN2 reaction crowd the electrophile and don't allow the nucleophile to come in but it can still be possible for E2
Appreciate your comment!
In 7:29 minutes, you managed to calm all my anxiety for my up coming exam. I am eternally grateful for your videos. Thanks.
Awesome to hear! I hope the exam went well. :)
I'm learning more I feel from these kinds of videos than all my classes.
Bro SAME
Since most professors cannot convey complex scientific information in plain English people can understand.
Awesome, happy to help!
u r literally the best. you can explain things that i don't understand in a 2 hour lesson with my teacher!!
Awesome!
This was such a clear, concise, and helpful video. Thanks a bunch!
You're very welcome! Glad you enjoyed it!
Hey, I just wanted to thank you for your videos. Because of watching them, amongst following a lot of other study habits, I was able to get an A in Ochem 1. *Cheers inside.* :)
oh wow! congratulations! That's awesome! You are very much welcome! :)
@@Leah4sci Thank you so much for all the help. I also really appreciate that you take the time to respond to messages. :)
I cannot believe it was this easy. I was almost going to cry because I couldn't understand the concept 🤧 thank you miss ❤️
You're welcome 😊 so glad I could help clear things up for you!
This is the best, most straightforward video I've seen on the topic
Thank you!
7 years later and its still helping people with exams! This was a great review for my Ochem Exam this afternoon, Thanks!
Orgo is timeless! Hope your exam went well
Can you believe I went through ochem1 without even memorizing this? In ochem2 and failing. RIP me
This is about to me
Sameeee
Same, and I feel the brunt of my ignorance beating my skull.
SAME.
I've been there too. 💔
The only video i could find that explains the diffrence between E1/E2 and Sn1/Sn2 Reactions, thanks
you're very welcome!
Beautiful video! I think the concept of stereochemistry inversion should have been brought up using chiral examples, but it was really informative regardless.
Thanks for the suggestion and for your kind words!
Very grateful for your videos! My professor reads from the book during lectures so your videos are a tremendous help. Thank you for sharing your talent and knowledge!
You're very welcome! Sorry to hear you aren't learning much in your class, but happy to know my resources are filling in the gaps for you.
This is such a cool idea and great video! I'm a chemistry prof in the US working on a similar approach on my channel. I like breaking down the concepts by videos, and giving an introduction to a topic (e.g., Assigning R/S stereochemistry) in 5 min or less!
Glad you liked it, and so happy to meet another life-long learner and teacher!
I have a test tomorrow and I'm comping on your RUclips channel
Thanks alot ❤
You're so welcome! Hope the videos helped and the test went well. :)
Thanks to U! An excellent short video.
You're very welcome!
one of the best explanation ever, thank you so much
You're very welcome, I'm so happy that it helped!
Very nice explaine organic chemistry thank you . 👍👍👍👍👍 from ethiopia 🇪🇹🇪🇹
You're welcome!
I struggled through Ochem 1, so I’m reviewing during my summer off so hopefully when I go back at the end of August I’m better off for Ochem 2 😬
Cross ur fingers
Get ahead of the game with my prestudy guide: leah4sci.com/prestudy
I learned more in this seven minute video than I have in a month in my class.
So glad to help you!
This is the best video explanation of this topic!
Glad you like it!
My final is in five days. My prof never taught us any mechanisms - just to memorize the reactions. I want a refund.
Thanks Leah!! I've sent my classmates to your channel.
You're so very welcome! I'm so glad to hear that this filled in the gaps for you and your classmates.
Leah4Sci wherever you are today, thx you girl and I hope you are a great doctor/scientist today xoxo
Even better, I'm still living my dream and teaching others how to reach their goals!
Absolutely perfect quick little review before my exam
Glad I could help and best wishes on your exam!
Highly appreciated for concise and clear explanation
Glad it was helpful!
Perfect explanation, thank you!
You're welcome!
This is helping me a lot I was so confused
Glad that the video was helpful!
It made me understand almost everything :) just how do you know where to get the H from in e1 and e2 reactions?
See the E1 and E2 videos in this series and let me know if you still don't understand after watching them all
leah4sci.com/nucleophilic-substitution-and-beta-elimination-sn1-sn2-e1-e2-reactions/
Your videos are so clear and easy to understand. Thank you so much!
I'm so glad you like them! You're welcome.
Leah u are a lifesaver
So happy to help!
This video may save my life for my recitation quiz today. Thanks!
You're welcome!
Just watched every single vid for this series that night before my final. Just now learning this. Rip.
How did it turn out?
this video is incredible. thank you so much
you're very welcome
Very good introduction to SN and beta elimination reactions imo, good job!
Glad you like it!
thanks, my organic chemistry teacher is really helpful, but in addition, this video was great for me to review for an exam
Glad it was helpful!
Nice voice editing.Seriously, I m in love with your voice.
thanks
Very informative and helpful
Glad you liked it
Wow I just learned this today and then your video comes up... THANK YOU
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Watching it for jee really helpful thankyou ma'am..❤❤❤.. ive some doubts regarding it how can i contact you
So happy to help! You can reach me by emailing me at leah4sci.com/contact
Great overview before exam !! thanks for your help
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Thank you very much.
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this is so helpful, thank you so much!
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It's exceptional..... I like it. Thanks.
Glad you like it!
Hey im so weak in organic chemistry and in want to make it perfect especially rxn meachanisms
For help with this and more, I recommend joining the organic chemistry study hall. Full details: leah4sci.com/join
Using all your Materials for the DAT.
Great!
thanks for the great summary
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thank youuuuu som much , i can't thank you enough for this. finally i understood it , you are the best.
Glad the video helped you understand the topic better! You are very much welcome!
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Another amazing video I wish I found sooner. You are my go-to for organic chem info!!
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Thank you teacher
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Does heat always help favor an elimination reaction, or does it depend on the nature of the base?
This is a complicated question. With all else being EQUAL, heat will favor an elimination reaction over substitution. But there's always a lot to take into account when choosing between SN/E reactions. 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/
thank you leah
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The dehydrobromination of isopropyl bromide requires several hours of reflux with alcohol KOH whereas in t.BuO-K+ / DMSO, dehydrobromination can be carried out in less than a minute at room temperature. Why this is so?
DMSO acts as an empirical catalyst speeding up the rate of reaction
Potassium tert-butoxide is a large, bulky base and is favored for elimination reactions because it cannot approach the carbon closely enough to react in a substitution. KOH, on the other hand, is much less sterically hindered and, without reflux at increased temperature, could react with the halide in a substitution reaction to produce a secondary alcohol.
So thanks 😍😍😍😍😍😍
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Cool videos and very helpful... 😉
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Why does heat stabilize the pi bond formation?
Increasing reaction temperature shows favor to elimination reactions over substitution. The explanation for this comes down to a discussion of the Gibb’s free energy values for elimination reactions being lower (more spontaneous) at high temperatures. The inverse of that is the Gibb’s free energy for substitution reactions is lower (more spontaneous) at low temperatures. Hope this helps!
best video less time...more knowledge
Glad you liked it!
Why would chlorine leave the carbon atom, in the first place?
Good leaving group
Good question! The ability for chlorine to leave the carbon atom is based on several factors, including the stability of the carbocation intermediate, the stability of the anion formed, and the type of solvent used. When the halide does choose to leave the carbon atom, it is attracted to (and solvated by) the polar solvent that is favored by SN1 reactions. So you can think of it in that way: it leaves because its attraction to the solvent is greater than its attraction to the carbon of the carbocation.
For the E2 reaction, wouldn't the most substituted Beta-Hydrogen be the CH3 on the right of Cl ?
No, we determine the degree of substitution by identifying the number of carbons directly attached to the carbon in question, not the number of hydrogens. The carbon on the right of the Cl would be primary, while the carbon on the left is considered secondary. See my pencil trick to learn more: leah4sci.com/pencil-trick
im sacrificing this section for tomorows paper, i just dont get even after watching alot of videos i just cant!
I'm sorry to hear you're struggling with this. For more help with this topic, feel free to contact me through my website: leah4sci.com/contact
Good video, on-time! :D
Glad you liked it
what does the H+ ion do in SN1 ?
Probably late but that just means that it's in an acidic solution.
H+ is simply how we show an acid catalyst. This could have come from various different aqueous acidic sources
Miss can you make online classes on organic chemistry using google meet
I can't do that, but I do have office hours as part of my Study Hall. leah4sci.com/join
ma'am, thousands of students including myself owe you their tuition fees
I take cash or card. Kidding, Glad my videos are helping
What about SNi and E1cb???
What about it?
Is it not included in the broad spectrum of elimination and subs?????
Madam,
Still the modulation not your explanations linger in me. 👆👏👏👏👏🥰 Am a small Tutor in KERALA STATE, S. INDIA
All the best!
Umm why sn2 are called bimolecular i can only see br and that's only 1 molecule reaction
For help with this and more, I recommend joining the organic chemistry study hall. Full details: leah4sci.com/join
My teacher took 6 days (1.5 hrs daily) to explain
Hope my video simplified it for you!
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I'm honored!! You're very welcome
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00:38 Are we gonna ignore the fact that you have a strong acid (H⊕) as one of your reagents? :q This means that someone should get protonated before anything else could happen. The only candidate for protonation here is the alcohol, but once it gets protonated, it won't possibly be able to act as a nucleophile. Before protonation, it was a weak nucleophile at most. After protonation, it would be even worse, because of the positive charge it would get. And this positive charge would make it keep away from the also positive carbocation. So besides protonating the alcohol, I don't think that you'll get any SN1 reaction here.
Another problem with this acid is this: _which_ acid in particular? In these type of reactions, solvents are very important, so you must be specific, because depending on the acid, there might be a different result. If you used hydrochloric acid, I don't think that the chlorine from the tert-butyl chroride would be so eager to leave the molecule, considering that this would increase the amount of chloride ions in the solution, and Mr. le Châtelier might frown upon it :q The acid actually seems to be driving the reaction in the opposite direction, making the molecule more stable as it is.
The fact that you got negative charges on stuff in an acid-catalyzed reaction should already blink some red lights. Because acids tend to get rid of negative charges as soon as they appear, or don't let them appear in the first place. And the fact that you started with an acid catalyst and didn't regenerate it at the end, is also kinda sus.
And lastly: why an acid at all? The alcohol can act as a nucleophile as it is (definitely better than if you protonated it). Sure, it is a weak nucleophile, but still a nucleophile, and it can attack a strong nucleophile (such as the carbocation left beind the chloride as it leaves the molecule) just fine. It is also a polar protic solvent on its own, favoring the SN1 reaction.
BonBonus point: atoms can't just fall off "on their own". That would be very unfortunate for chemistry and stability of matter in general :q And they can't just "choose to leave" (regarding your reply to someone else), because atoms are not persons, they don't have their own mind and they cannot "choose" anything. They can be _made_ to leave by some external factors (in this case, the solvent).
I'm sorry, but this is too complex of a question for a RUclips comment. Please, email me at Leah4sci.com/contact
@@Leah4sci Yeah, right… So that you could advertise some more of your tutoring sessions? :q I'm well accustomed with your canned replies here, and as I already said I'm not really interested, I don't need tutoring. And this wasn't really a question. More like a critique. But whatever…
You are amazing! Love your videos thanks so much!
You are very much welcome :)