Acidity of Aromatic Compounds Vid 8 Orgo Acids and Bases
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- Опубликовано: 17 окт 2024
- leah4sci.com/ac... presents: Acidity of Aromatic compounds - Video 8 in the Acid/Base sereis
Need help with orgo? Download my free guide '10 Secrets to Acing Organic Chemistry' HERE: leah4sci.com/or...
Video 8 in the acid/base series takes this concept to a more advanced level looking at the resonance provided by aromatic compounds.
Catch the entire series, along with my acid/base cheat sheet and practice prolem set on my website: leah4sci.com/ac...
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It's the first time I understand the concept of acid base. Thank you so much for your efforts. 🖤
You're very welcome! I'm so glad this helped it click for you!
Just watched the entire series, it was very helpful! Thank you so much for donating your time to make these:)
Leah Fisch mam, how to find acidity order of benzoic acid, formic acid and acetic acid
You're so welcome, happy to help!
Thank you for teach me distinguished about weak or strong acid in organic chemistry.
You're very welcome!
Just came through your organic thing it's superb.
Thank you so much 🙂
-NH2 is an activating group for benzene, it increases electron density via resonance. -NO2 is a deactivating group and decreases electron density via resonance. Is this concept relevant when considering the acidity?
Yes! That's a great connection to make. -NH2 is an electron donating group and, therefore, would be resistant to donating electrons towards an already negative oxygen on the other side of the ring. -NO2 is an electron withdrawing group and, therefore, would welcome extra electron density from the opposing negative oxygen. The electron withdrawing group being on the opposite side of the ring actually stabilizes the conjugate base and increases the acidity of the compound.
For more on these directing effects, make sure to see my tutorial at leah4sci.com/ortho-meta-para-directing-effects-in-eas-reactions/
Really thankyou mam you helped me alot to clear confused topics more by going to the fundamentals you are now the second best teacher i have taught from.
It's my pleasure, happy to help!
Why does meta-position allow for an extra resonance possibility while other positions do not? Could I get a little more insight pls :) awesome helpful video by the way
I cover this in detail in the EAS sigma complex / resonance video here: leah4sci.com/electrophilic-aromatic-substitution-mechanisms-and-reactions/
@Leah4sci I've been studying this sense and your video will be helpful to me. Thank you so much!
Thanks for the video, but why can't the meta N02 do resonance too? I understand that it can't, but why not?
try to delocalize the loan pair of electrons from oxygen in m-nitrophenoxide ion ....you cant place the electrons any where because evry carbons valency is filled ...
The electrons resonate between the 2 oxygens and nitrogen to maintain a net neutral charge. if you try to resonate the pi electrons into the ring you'll be left with an extremely deficient situation on the oxygen atoms (try it then do a formal charge to understand)
Resonance is present in benzoic acid and the pi electrons of carboxyl group resonate into the benzene ring. But you said at 1:37 that it is not possible in carboxyl group. That has confused me. Please answer my query. Thanks
The pi electrons in the carboxy group of benzoate do NOT resonate into the benzene ring. Those two sets of pi electrons are separate, and they do not create a single system of conjugation.
Hey, first of all, thank you for your videos !
Second, I don't really understand why at around 6:12 you say that when there is more resonance, it's less stable, so it is a weaker acid. Isn't the definition of a strong acid a really unstable molecule that is very willing to give away its H+? And I thought that more resonances meant more stability as the molecule can "collapse" to something else when in need, it won't dissociate.
If you listen to the audio one more time, I believe I say "...and when you have slightly LESS resonance, it's slightly less stable." You can check the closed captions as well. Let me know if you have further questions on this!
What would be the order of acidity of 4-aminophenol if compared to ortho-, meta- and para-phenol?
I have a membership site that includes a tutoring & support group that I think you'd benefit from because you'll get to post questions like this and more. Details here: leah4sci.com/join
1:47 I'm just trying to make sense of this my understanding is that you can't resonance into the benzene ring because the 2 Os on the COOH would rather bear the negative charge (as opposed to the Cs in benzene)? That's what I'm getting
Delocalized electrons are not capable of resonating into the ring primarily because the carbon of the carboxylic acid cannot exceed the octet rule. Then, if the pi bond of the carbonyl were to move towards the ring, that would leave the oxygen with LESS than an octet, which is also not possible. The presence of the two oxygens next door to each other effectively closes off the 'route' of electrons to the ring.
@Leah4sci ok thanks 👍
thanks for video ı have a question which one is more acidic? phenol or anisole? thanks...
Consider that anisole is otherwise known as methoxybenzene. It is a methyl ether attached to a benzene ring. That means no hydrogen is directly bonded to the oxygen in anisole, as is the case with phenol. I hope that helps! If you want more guidance with questions like these, join the Orgo Study Hall at studyhall.leah4sci.com/join
why do we draw the conjugate base to determine acidity? 2:50 how do i know to draw the conjugate base and not the conjugate acid?
We are comparing the acidities of the three phenol groups at this time in the video. They, in themselves, are acids with protons to donate. You cannot have a conjugate acid of what is already an acid.
Each of those molecules then has a conjugate base which can be drawn as the same structure but without its hydrogen. Because there is a direct relationship between the conjugate acid-base pair, we know that the most stable conjugate base (i.e. the one happiest without that extra hydrogen) came from the strongest acid (i.e. the one that gives up its hydrogen most easily).
Where can I find the video on BASICITY for AROMATICS video that was recommended at the end of this video?
I haven't finished the video yet. For more help with this and other orgo 1 & 2 topics I recommend joining the orgo study hall. Full details: leah4sci.com/join
Why does the structure with NO2 in the para position have 5 resonance structures and the structure with NO2 in the meta position has 4 resonance structures?
I'm sorry, but I don't offer tutoring through RUclips comments. For help with this and more, I recommend joining the organic chemistry study hall. Full details: leah4sci.com/join
It's because in the para position the electrons on the nitrogen can form a C=N double bond, causing the positive charge to go onto more electronegative atom (the nitrogen) which is more stable. It would be more stable because the carbon would have a full octet.
I don't understand why phenol with the NH2 group attached is weaker than just phenol, I thought all electron donating groups increase acidic character
NH2 does not a donating group it's reson -to make a H-bonding between NH2@nd OH
The electronegative nitrogen tries to deflect the lone pairs coming from oxygen due to resonance thereby making it a weaker acid
Nh2 discourages resonance
@@divyaarora5068 this really goes against what were taught considering electronegative stuff likes electrons so no that doesnt sound right however it has a lone pair and 8 electrons so it doesnt want anything else so why take anything . and the lone pair actually stays put and repels anything incoming so thats what i understood about it
The acidic group on phenol is the OH. When deprotonated the O- is stabilized by resonating its negativity into the ring. However, if a group like NH2 is present, the NH2 competes trying to put its OWN negativity into the ring. Competition has the opposite effect in this case
Where can I find the basicity of aromatic compounds video?
It's still on my to-do list :) I post free videos as I have time and am always looking for suggestions. For more help with this topic in the meantime, contact me through my website: leah4sci.com/contact
Concept is too easy to understand. Thank u
You're welcome! :)
at 6:00 why cant you just run them around one more time and cross over the nitrogen bonded at the meta phase then? please anyone answer
If you “run them around again”, the pi electrons in the ring are still unable to resonate into the nitro group at the meta position. Doing so would simply place the pi electrons back into their starting positions. At no point will a resonance arrow bridge the carbon holding the nitro group (like it did with the nitro group in the para position).
Why does resonance and distributing the negative charge make it a better acid?
Resonance allows a charge to move throughout the ring. This makes it easier for the hydrogen proton to leave. The easier a compound can let go of a hydrogen and still remain stable, the stronger the acid. The same with sulfuric acid in a sense. It is able to easily let go of a hydrogen and remain very stable. Thus, sulfuric acid is a strong acid.
A strong acid is one that forms a stable conjugate base. When an acid donates a proton you're left with a negative charge on the conjugate base. IF you can stabilize that base you'll make it happier and more likely to form.
The more stable the conjugate, the more likely it forms, the FASTER it forms, the stronger the acid that gives up the proton TO form this stable conjugate base
why intermolecular attraction on nitro at para position is not considered as many ques has this case please explain .please make a video on some important basic examples
At which specific point in the video? For more help with this topic, I recommend joining the orgo study hall. Full details: leah4sci.com/join
"Bonus resonance"....I never heard that before....but I love it! ❤ 😂
Glad you like it!
What is a stronger base phenylamine or 1,3 diaminobenzene
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/
Why couldnt the black electrons resonance onto the Nitrogen at the META position? ..but it could at the PARA position?
At which specific point in the video?
why does the meta substituted NO2 only have 4 resonance structures (at 5:55) ? why cant it have 5 resonance structures like the para substituted ring?
what if there was a ortho nitro phenol
what if there was?
U help me so much . thank You
You're very welcome, so happy to help!
this video is very good. acidity is a common condition. acido plan syrup of Planet Ayurveda is very effective. I am also using this syrup and ger relieved
Glad you enjoyed the video!
Thank you.
You're welcome! :)
THx!!!!
you're very welcome!
this was so confusing
I'm sorry you feel that way. For specific questions on this video or on this topic, please contact me through my website at Leah4sci.com/contact
✅✅
thanks!
Can someone please explain how the line pair of NH2 discourages resonance? Is it because nitrogen is more electronegative than hydrogen atoms compared to nitrogen in NO2?
The nitrogen atom in the NO2 group is positively charged, while the nitrogen atom in the NH2 group is neutral BUT with a lone pair attached.
When we talk about the acidity of this group of compounds, we are talking about how well the hydrogen will dissociate from the OH group at the top of the molecule. When that hydrogen does dissociate, it creates a negatively charged oxygen. And a negatively charged oxygen would prefer to resonate towards something positively charged (like nitrogen in NO2) rather than towards a nitrogen atom with a lone pair attached.
Therefore, the presence of the NH2 and its accompanying lone pair discourages resonance and decreases the acidity of the compound.