Dave, appreciate how you explain from fundamentals why one product is favored, not just give some rule which appears arbitrary. This was always one of my biggest problems with Chemistry, it seemed to be a collection of rules with no coherent explanation.
I was feeling discouraged about organic chemistry until I met you!!! Thank you so much for all the work that you do!!! You are a true blessing for all the struggling college students :')
I dont know how i discovered your channel but im happy about that, my mother language is spanish and there's no organic chemistry videos with this quality at least on youtube! keep doing your stuff.
Thanks for the quality of your videos! I'm from Brazil and many topics of chemistry, we suffer for not having quality video lessons as yours, thank you!
Thanks for not just telling me what to do but WHY WE DO IT. My orgo professor is great but we're in an accelerated course so sometimes the "why" is missed. To me, I just can't do the "what" without the "why".
Your classes are awesome...my addiction to chemistry is increasing day by day ...thanks a lot sir 😍😍..and I also suggest all of my friends to watch your lectures for clear conception .
I can't thank you more, for it's the first time I distinguish Zaitsev from Hofmann. I used to think they are the same person that refers to the same process. And now, I feel I might pass the exam.
oh thanks Professor Im from Brazil and your videos are so good, even they are in English.I understood everything about this organic reactions...tks a lot
Thank you very much... you are highly organized when you explain with such great skills in addition to your knowledge that make all of what you said understandable and clear...appreciate your efforts.
Wow u cleared my doubts...thank u sir...each and every students ..can understand your teaching....many u tube i watched....but urs very crystal clear..not skipping any small points....thank u sir....from india....
i didn't know i could understand organic chemistry until i found your video, i had to read the subtitles because i speak spanish but i understood everything !! thank you very much
QUESTION - In the second portion of the video when you're explaining the first example - when the Bromine leaves the molecule why is there a methyl group in the first outcome? There was no carbon there before why is there one now? I hope I'm asking clear enough. Other than that amazing video! Thanks so much.
EXAMPLE OF NUCLEOPHILIC SUS REACTION 1.REPLACEMENT BY CN- GROUP RX+KCN---->RCN+KX WHEN AgCN IS USED IN THE PRODUCT WE GET RX+AgCN--->RNC+AgX (ISONITRILE) WHY IS THIS SO?
Hello Prof. Dave. I'm following these tutorials right now. Very helpful. But sometimes I still have questions, and I dont know if you hang around these videos cause they are quite old. I'll try and ask them anyway. So my doubt about this is, in the examples part of the video, is there a specific reason why you would have us draw the chair for compound number 2 but not for number 1? Isnt that a cyclohexane as well? And isnt the carbon on the left of Br still a potentially working beta carbon? Ty so much man you know what you are doing and you are definately making me interested in the subject. Btw if Prof Dave couldnt answer maybe some1 else will, I would still appreciate the help.
For the first one, the carbon on either side has both protons available for elimination, so it is a given that one of them will be in the proper orientation, we don't have to check. With the second, there is a neighboring substituent, so we have to look at the chair.
@@aayushsharma3655 no. It is Saytzeff/Zaitsev/Saytzev's rule depending upon which language you speak. Zaitsev was his name in Russian but his English name spelling was Saytzeff and our education system is adopted from English thus we also call it Saytzeff rule. Open a Russian authored book and you'll see it as Zaitsev's rule.
I love this well understood video and the ones on historical figures too. They are great Prof. Dave ! Anyway, while viewing this Hoffman/Zaitsev video I found it informative, but out of curiosity, I always wondered why the lone hydrogen attached to the Carbon holding the Halogen itself is never involved in any reactions where bases are grabbing protons. They only go after hydrogens on nearby Carbons. I would assume that there is one there since stable Carbons have 4 bonds. Maybe I am missing something.
good question! so the proton on the carbon that bears the halogen is not acidic, because if a base grabbed it, where would the resulting negative charge go? it would be localized on the carbon. only if a beta proton is abstracted can a pi bond form because it is the leaving group that is able to leave.
@@ProfessorDaveExplains Thanks so so much. I am a Man who always loved learning about what some people would call "the craziest things" !! Science is my favorite and my burning desire to learn is still with me even though my childhood days are many years gone. Thanks again Prof. Dave And for the informative videos ! ☺
Hey Dave, Great videos. Could you possibly do a video showing this kind of problem except where the LG is equatorial and the chair must do a ring flip to do the reaction? Having trouble with that and I know that it will be on my final. Colin
So I know when there is a tert-butyl group and you draw it in chair form, the tert-butyl is always in the equatorial phase. Why is the dimethyl drawn axial? (or does it not really matter?)
Yes i had the same question...there are 3 substituents all in axial position....wouldnt it be too much unfavourable to switch to that position for the ring ? wouldnt it be almost as an anchor if you got 3 substituents in equatorial position ?
In the first example (9:00min onwards) why is the dashed hydrogen the one that gets eliminated for the Hoffman product? I thought that the proton that gets eliminated needs to be on an adjacent carbon and anti to the leaving group? thanks! :)
at the end with bromine and methyl on cyclohexane and methoxide going to zaitsev and hoffman? that proton is not on the dash, the methyl is on the dash! three hydrogens are on it, one will be anti at any given time.
Sorry! my bad! I meant 6:00min. I have no idea why I put 9min. Its the first (top) example of two that you do. Thanks for coming back to such an old video. Im sure the answer is straight forward but I just cant see it :)
Anna Kornak that would be a disubstituted alkene, i'm guessing because of sterics it would be less stable than trans-2-butene, and somewhat comparable to cis-2-butene, though i'm not sure with absolute precision whether it would be slightly more or less stable than cis-2-butene. i'll go ahead and guess slightly more stable since double bonds are shorter than single bonds.
Very good video you've done good job man but i got a question. According to reaction when bromcyclohexan is turned into few Hoffman products, as far as kinetics would drive this reaction, will there really be a double bond formed with that atom of Br? I mean wouldnt it rly prefer a double bond creation in the circle? Sorry if my question is explained in ur vid.
Can the example at 9:00 be Sn2 or E2? The carbon is only secondary, so both should work with the small strong base? Or is the ring itself just too hindered?
+Green Marble the steric hindrance from the isopropyl would certainly reduce the amount of SN2 but yes there could be some substitution. this is just examining the case where elimination occurs, which could be ensured easily by, say, heating the reaction vessel.
not reliably, i wouldn't think, as it's all about sterics, and although lighter bases are usually less sterically hindered, that isn't a rule by any means.
isn't the isopropyl in the axial position going to make this conformation reaction unfavorable and a slower reaction? Therefore having to do the reverse chair?
+T Joseph for the first one, all of the adjacent carbons have at least two protons available for extraction, so we know they all have a proton that is anti to the leaving group. if you wanted, you could draw the chair to prove this to yourself. for the other example, we have to draw the chair to see if the tert-butyl group is anti to the chloro or not, as this will determine what kind of products we will get.
someone translated my biochemistry videos to spanish and i can't figure out who it was! they did an amazing job. see if you can find out and ask them to do the rest of my stuff, i would be willing to pay them.
hmm that kind of terminology is not used very often, but i assume a primary proton is one found on a primary carbon, secondary proton on secondary carbon, etc.
Need OChem help? Find me and all the resources you need on Chemmunity: chemmunity.info/dave
I told everyone in my oc class about you every single of them are learning with your videos now :D
thanks for spreading the word!
@@ProfessorDaveExplains me too, they are all your recent subscribers, they love you man!
A friend told me about this channel, and what turns out is sir you are underrated.
Sagarnil Chakraborty yeah really.
Dave, appreciate how you explain from fundamentals why one product is favored, not just give some rule which appears arbitrary. This was always one of my biggest problems with Chemistry, it seemed to be a collection of rules with no coherent explanation.
yeah so much gatekeeping lol
I was feeling discouraged about organic chemistry until I met you!!! Thank you so much for all the work that you do!!! You are a true blessing for all the struggling college students :')
You are by far with the most clear explanation. Very well done ! U have an extra subscriber today ;-)
You make things so easy to understand; you always explain clearly why things occur. THANK YOU!
I dont know how i discovered your channel but im happy about that, my mother language is spanish and there's no organic chemistry videos with this quality at least on youtube! keep doing your stuff.
when i said organic chemistry videos I mean organic chemistry videos in spanish languague
Thanks for the quality of your videos! I'm from Brazil and many topics of chemistry, we suffer for not having quality video lessons as yours, thank you!
Thanks for not just telling me what to do but WHY WE DO IT. My orgo professor is great but we're in an accelerated course so sometimes the "why" is missed. To me, I just can't do the "what" without the "why".
Your classes are awesome...my addiction to chemistry is increasing day by day ...thanks a lot sir 😍😍..and I also suggest all of my friends to watch your lectures for clear conception .
my professor explained the same topic for 2 to 3 days which u made possible in just 10 mintues...keep up the good work :D
love the visual explanation of the chair conformation and why one of the H is not available. You are the best thank you so much.
I can't thank you more, for it's the first time I distinguish Zaitsev from Hofmann. I used to think they are the same person that refers to the same process. And now, I feel I might pass the exam.
How’d your exam go?
@@PunmasterSTP Of course I passed, and got more than expected marks. Can't thank Dave enough.
oh thanks Professor Im from Brazil and your videos are so good, even they are in English.I understood everything about this organic reactions...tks a lot
sir it's 3-bromobut-1-ene.
tanks a lot .. u r the best on RUclips
Thank you very much... you are highly organized when you explain with such great skills in addition to your knowledge that make all of what you said understandable and clear...appreciate your efforts.
Wow u cleared my doubts...thank u sir...each and every students ..can understand your teaching....many u tube i watched....but urs very crystal clear..not skipping any small points....thank u sir....from india....
you are very clear at explaining, i will share your videos with my classmates. blessings.
he knows a lot about science stuff. professor dave explains everything!
Love how helpful these videos are Professor!
Keep up the great work
I cannot thank you enough for the awesome explanation !
Thank you professor Dave this cleared up a lot of things for me for my Ochem midterm
I know it’s been awhile, but how did your midterm go?
I always try to find your videos when i study, you are the best ever thanks alot i wish you can do all the chm :(
very coherent explanations still relevant for OC
i didn't know i could understand organic chemistry until i found your video, i had to read the subtitles because i speak spanish but i understood everything !! thank you very much
Why you deal with E2 you should select SN1 because it made us action +3
and once again i learned more from a 10 min youtube video than from 1.5h lecture in school
Gutes Video! I did understand it much easier than in the most german OC videos.
This video needs to get more views
you literally saved my exams!!
How did those exams go?
That was such a good explanation. Crystal clear.
Actually I was in confusion which will be major product but this sir made my life easier thankyou so much sir
Thanks Chemistry Jesus
so when do we use saytseff and when hoffman?
Thank you so much professor Dave.you are great.
QUESTION - In the second portion of the video when you're explaining the first example - when the Bromine leaves the molecule why is there a methyl group in the first outcome? There was no carbon there before why is there one now? I hope I'm asking clear enough. Other than that amazing video! Thanks so much.
there was a methyl! it's the dash bond.
EXAMPLE OF NUCLEOPHILIC SUS REACTION
1.REPLACEMENT BY CN- GROUP
RX+KCN---->RCN+KX
WHEN AgCN IS USED IN THE PRODUCT WE GET
RX+AgCN--->RNC+AgX
(ISONITRILE)
WHY IS THIS SO?
Thank you so much! I was struggling with this in class and you made everything so clear! thank you
How’d the rest of your class go?
This guy is the goat
How am I learning more from a free video than I am from the college class I’m paying $thousands$ for?
Lmao, Nice intro, You won a Suscriber, a chemist student from Venezuela :D and thank you!
Earned a sub!! Thanks so much for the help man!
Hello Prof. Dave.
I'm following these tutorials right now. Very helpful. But sometimes I still have questions, and I dont know if you hang around these videos cause they are quite old. I'll try and ask them anyway.
So my doubt about this is, in the examples part of the video, is there a specific reason why you would have us draw the chair for compound number 2 but not for number 1? Isnt that a cyclohexane as well? And isnt the carbon on the left of Br still a potentially working beta carbon?
Ty so much man you know what you are doing and you are definately making me interested in the subject.
Btw if Prof Dave couldnt answer maybe some1 else will, I would still appreciate the help.
For the first one, the carbon on either side has both protons available for elimination, so it is a given that one of them will be in the proper orientation, we don't have to check. With the second, there is a neighboring substituent, so we have to look at the chair.
God Bless this man
In germany we call it Saytzeff and Hofmann product. That's weird because they're actual names.
Russian translation can be awkward and vary in various books and authors
Same in India !
fellas the rule is called Saytzeff rule which was given by chemist Zaitsev.....so nobody is studying different
@@aayushsharma3655 no. It is Saytzeff/Zaitsev/Saytzev's rule depending upon which language you speak.
Zaitsev was his name in Russian but his English name spelling was Saytzeff and our education system is adopted from English thus we also call it Saytzeff rule. Open a Russian authored book and you'll see it as Zaitsev's rule.
Very helpful. Thank you very much :D
A legend describes what you are
I love this well understood video and the ones on historical figures too. They are great Prof. Dave ! Anyway, while viewing this Hoffman/Zaitsev video I found it informative, but out of curiosity, I always wondered why the lone hydrogen attached to the Carbon holding the Halogen itself is never involved in any reactions where bases are grabbing protons. They only go after hydrogens on nearby Carbons. I would assume that there is one there since stable Carbons have 4 bonds. Maybe I am missing something.
good question! so the proton on the carbon that bears the halogen is not acidic, because if a base grabbed it, where would the resulting negative charge go? it would be localized on the carbon. only if a beta proton is abstracted can a pi bond form because it is the leaving group that is able to leave.
@@ProfessorDaveExplains Thanks so so much. I am a Man who always loved learning about what some people would call "the craziest things" !! Science is my favorite and my burning desire to learn is still with me even though my childhood days are many years gone. Thanks again Prof. Dave
And for the informative videos ! ☺
YOU ARE A LIFESAVER! Thank you :)
Hey Dave,
Great videos. Could you possibly do a video showing this kind of problem except where the LG is equatorial and the chair must do a ring flip to do the reaction? Having trouble with that and I know that it will be on my final.
Colin
+Colin McCorkle i will add it to the list! though it won't be in time for your final. happy to do Skype tutoring if you like.
+Professor Dave Explains Hey Dave,
How much do you charge for the Skype tutoring?
Colin
Thank you so much Prof Dave, for finally making chemistry an interesting learnable system for me.
By far the best ❤😘
good teaching sir
thanks sir for this wonderful lecture
Thank you so much sir..... It help me a lot
So I know when there is a tert-butyl group and you draw it in chair form, the tert-butyl is always in the equatorial phase. Why is the dimethyl drawn axial? (or does it not really matter?)
every chair has two conformations, and every substituent on the chair will be axial in one conformation and equatorial in the other.
Yes i had the same question...there are 3 substituents all in axial position....wouldnt it be too much unfavourable to switch to that position for the ring ? wouldnt it be almost as an anchor if you got 3 substituents in equatorial position ?
Thank you so much Prof. Dave :)
In the first example (9:00min onwards) why is the dashed hydrogen the one that gets eliminated for the Hoffman product? I thought that the proton that gets eliminated needs to be on an adjacent carbon and anti to the leaving group? thanks! :)
at the end with bromine and methyl on cyclohexane and methoxide going to zaitsev and hoffman? that proton is not on the dash, the methyl is on the dash! three hydrogens are on it, one will be anti at any given time.
Sorry! my bad! I meant 6:00min. I have no idea why I put 9min. Its the first (top) example of two that you do. Thanks for coming back to such an old video. Im sure the answer is straight forward but I just cant see it :)
Wow you are done great job sir thank u very much...
tHIS dude's a literal saviour
How can you have tetrasubstituted? Wouldnt there not be a beta hydrogen to produce the double bond?
Greetings from Germany :) love these videos
Thank u sir❣️from india
where would the stability of an alkene with two methyls on one carbon and 2 hydrogens on the second carbon rank among these? (CH3)2-C=C-(H)2
Anna Kornak that would be a disubstituted alkene, i'm guessing because of sterics it would be less stable than trans-2-butene, and somewhat comparable to cis-2-butene, though i'm not sure with absolute precision whether it would be slightly more or less stable than cis-2-butene. i'll go ahead and guess slightly more stable since double bonds are shorter than single bonds.
Shouldn't the isopropyl at 08:30 prefer the equatorial comformation ?
yes but elimination can't proceed from that chair
Thanks sir
Love from India
You are a lifesaver
Excellent episode....
I was trying to figure out what kind of base boron is and how it's just floating around with two electrons
Very good video you've done good job man but i got a question. According to reaction when bromcyclohexan is turned into few Hoffman products, as far as kinetics would drive this reaction, will there really be a double bond formed with that atom of Br? I mean wouldnt it rly prefer a double bond creation in the circle?
Sorry if my question is explained in ur vid.
Adam mackovčin no double bond to bromine! bromine is the leaving group. a double bond will be formed between two carbon atoms.
Can the example at 9:00 be Sn2 or E2? The carbon is only secondary, so both should work with the small strong base? Or is the ring itself just too hindered?
+Green Marble the steric hindrance from the isopropyl would certainly reduce the amount of SN2 but yes there could be some substitution. this is just examining the case where elimination occurs, which could be ensured easily by, say, heating the reaction vessel.
+Professor Dave Explains Awesome! Thanks so much.
very good video
Great video!
Thanks , the best explication ever !!
Thank you so much 😊😊😊
Is there a mathematical relationship between the Hoffman and Zaitsev product distribution and the molecular weights of the bases?
not reliably, i wouldn't think, as it's all about sterics, and although lighter bases are usually less sterically hindered, that isn't a rule by any means.
isn't the isopropyl in the axial position going to make this conformation reaction unfavorable and a slower reaction? Therefore having to do the reverse chair?
but the leaving group must be axial, so it must be in that conformation, which means it will just be a slow reaction
continuity error!
starts episode with red flannel on and ends with gray flannel??
Cmon professor dave!
oh the sign off is its own thing sillypants
Hoffman? More like “You’re the man!” 😎
Very well explaination
Aren't those Saytzeff and Hoffman products are is Zaitsev?
I'm confused cos we are studying about Zaitsev's rule and don't want to mix up the 2
yes Zaitsev and Saytzeff mean the same thing they are just alternate spellings!
@@ProfessorDaveExplains ah ok. Thanks for the surprisingly quick reply :)
Dude you are the best!
Thanks professor ;)
Why did you put isopropyl group above?? What if ring flips?? Do we get same or different products??
that's the conformation from which E2 proceeds
du bist ein Ehrenmann
Thank you
Oh my God! I understand why for the first time in my life!
thanks for the help !
Does the symmetry effect it? (I mean like is only wedge Hydrogen gonna attacked by Nu?)
amazing examples!!!! (:
At 7:32 ...how is the Hoffmann product like that....that's not beta elimination....please explain
sure it is beta
How do you know when to draw the chair for the ring?
why wouldn't you draw a chair for the first reaction, like you did for the second one?
+T Joseph for the first one, all of the adjacent carbons have at least two protons available for extraction, so we know they all have a proton that is anti to the leaving group. if you wanted, you could draw the chair to prove this to yourself. for the other example, we have to draw the chair to see if the tert-butyl group is anti to the chloro or not, as this will determine what kind of products we will get.
+Professor Dave Explains
for the first reaction, why can't you have 3 products? There is a adjacent carbon on the left as well.
Can anyone translate his videos to spanish?. There are not good videos in that language and i think he is a great teacher. :c
someone translated my biochemistry videos to spanish and i can't figure out who it was! they did an amazing job. see if you can find out and ask them to do the rest of my stuff, i would be willing to pay them.
thank you so much
is zaitsev and saytzeff the same person?
They have like a Dr Jeckyll and Mr Hyde type of Situation; In the night he‘s Saytzeff
Nice vid, but could you explain what secondary and primary protons are? Google didn't really help me on that one....
hmm that kind of terminology is not used very often, but i assume a primary proton is one found on a primary carbon, secondary proton on secondary carbon, etc.
That would make sense...came across this at like 7:28, but I think I get it with that explanation. Thanks!
oh hah, i forgot i said that! yeah i'm not sure how universal that language is but that's what i meant :)
thank you!! helpful