E1 reactions | Substitution and elimination reactions | Organic chemistry | Khan Academy

[@tekashi5962]

0:00 I have no idea what’s going on already

[@19jewels95]

I hate my mind. All these organic chem videos with their reactions and electron movement, it makes no logical sense to me... It's as if people are just making up stories every time >< "Like oooo, this one here is verrrrry negative! and so it'll be super attracted to the positive one here"

[@batsman46]

+Julie Lam thats what a mechanism is lol.

[@bachansingh7586]

Julie Lam 😂😂😂 but you have mug up that tale

[@silphate9836]

yes, those ACTUALLY ARE made up stories... we are not sure if that's how it works but those explain the observed products, transition states, rates and intermediate compounds...

[@Akordio94]

Preach!

[@vidyaammu3519]

Wish I had a teacher like you

[@AdultsSociety]

Easy to understand explanations, love this type of learning!

[@divinebannerman]

Simply phenomenal

[@Mimicoops]

I know this is E1 but what about Sn1? Cause we're dealing with a tertiary carbon so does that mean they would compete?

[@03raq]

I think the only reason why it is not sn1 is because the weak base didn't substitute the bromide

[@silphate9836]

@@03raq No, in Sn1 the bonds formed after substitution are stronger than the bonds before substitution which makes it exothermic whereas as in E1 weaker bonds are formed making it endothermic and that means that at low temperatures Sn1 will take place and E1 will take place at high temperatures (i am not 100% sure but that's at least what I think... :p)

[@nikolavideomaker]

@@silphate9836 all of this chemical reactions are balanced between elimination and substitution. In this case, because the C atom is tertiary, it is pretty hard for a substitution( not much space for the other group to attach to the tertiary C) to occur. So, 99 of the products follow an elimination reaction. But, there are still a few which possess a O-CH2-CH3 group.

[@chabloc7438]

Man sn1and e1 go hand to hand but one product is major and other is minor ,here sn1 does not occur either due to temp difference as e1 is preffed at high temp ,or the week base may have more basic property

[@missrashmi91]

U r a life saver!!

[@ecs_083kumarankitsingh5]

I simply love ur videos!!

[@thijmenwillems9408]

Thanks, very helpful!

[@liamha2039]

You are incredibly good! I had a hard time understanding this in my class even though I sat there listened for 2 hours. You made this clear and easy to understand in just 10 mins. That's amazing! Thank you very much!

[@winnethisoma8396]

8 years later and this is still completely relatable

[@shubhankarpaul2653]

Love from 🇮🇳 I'm revising with Khan academy organic, and enjoying it. On 13 th sept my medical entarce ex am(NEET) to be conducted.

[@oberyn2474]

did you crack it?

[@KSals]

As everyone is saying or asking, let me clarify. This would not be an E1 reaction, it would be an SN1 reaction. Everything he said is right if heat was applied, (I don't believe he mentioned heat). So if the reaction had a delta symbol for heat, then everything he said was true. If there is no heat then it would have been an SN1 reaction. That's the only difference on tertiary carbons with weak bases. Hope that helps.

[@cmhardin37]

K Sals No, you're wrong. substitution did not take place.

[@KSals]

Unless you know something I don't. As I was taught, and as I have researched to confirm (not very much admittedly); when you have a tertiary carbon reacting with a weak base and there is little to no heat applied, a substitution reaction will be the dominant reaction over an elimination reaction. www.masterorganicchemistry.com/2012/12/19/deciding-sn1sn2e1e2-4-the-temperature/

[@cmhardin37]

O. I was confused. Yes I think you're right. I was saying that what sal showed was an elimination, but your saying it should have been a substitution and I think you're right.

[@cmhardin37]

My chart says it is 50 50

[@KSals]

Yeah, and that's why all the comments below are people who are confused. It is a 50/50, I think Sal just missed it is all. It leans more to substitution when there is little heat applied. Pretty much any time there is heat, you can bet that it will be an elimination.

[@luscinia_74]

At 5.56 why doesn't the oxygen attack carbocation instead of hydrogen?

[@Coastable]

That would become an SN1 reaction which is not what we are trying to achieve. We want to form a double bond with the carbon cation (E1).

[@fay407]

It could be but the conditions will be controlled to drive the reaction to go E1 instead of SN1

[@vctrylghtspr91]

I understand!!!!

[@Zlopras]

thank you, mr. lifesaver

[@lnr08f]

Why doen't the nucleophile just attack the carbanion like in Sn1 reactions? Once it does that then there will be a positive charge on the Oxygen, but the Br(-) can then just swipe the H off the HOCH2CH3 and make it neutral like it does in the Sn1

[@ARTownley]

Have my first year organic chemistry exam tomorrow for uni, quick look over elimination and subsitution! Thanks this helps me set things straight in my mind! Dreading tomorrow :(

[@15vanessakavishe80]

Amaizing explanation thank you!!

[@Sikabdo]

صابوني نايس ا عشيري Really You're So good

[@leratoshasha1224]

Thank you From 🇿🇦SA

[@Dhilan100]

the rate determining step is the slowest step .. in this step its the hetrolytic cleaving of the bromine to form a bromide

[@sanjeevokhandiar4596]

I want to understand that when the carbocataion is formed in 1st step then why the week base did not combine with the carbocation directly. Since it is slighly negative charge and carbocation is positive charge?

[@AnthonyVoutas]

@Bio1993Hsapien: In E1 the solvent doesn't Substitute for the leaving group (like S1), it Eliminates it.

[@curtpiazza1688]

Beautiful! 😊

[@s0m0c]

Gracias.

[@xBreaker666]

your drawings are amazing :)

[@x3chrrstiney]

Why wouldn't the partially electronegative O directly attack the carbocation?

[@samus1225]

What if you had chosen to make the pentane group based upon the 2 carbons that are beneath the bromine rather than to the right of the bromine?

[@johncarson2842]

thank you good sir!

[@priscyllacarvalho3381]

You made the double bond using the carbon to the right.. would it make a difference if it were done with the carbon to the left? they would both be major products, right??

[@johnmandrake8829]

this should also work with Sn1, so for this rxn we should get two different products, since its Sn1/E1 there wll be inv + retention for each, a total of 4 products then?

[@vart12345]

nice talk.

[@RoflCopter58]

@SilkiestShark u must really like chemistry

[@recur9759]

You talk just like DJ Akademics. I seriously love your vids. lol

[@nilpatel9096]

I'm dead

[@koenjanssen5838]

Is bromoethane been produced also? because the water splits of to create a carbocation and then the negative bromide reacts with it (SN1 reaction)?

[@virginiaferruccio3020]

Great!

[@honshoku]

uhm Thank you Khanacademy for your videos! It has helped a lot. However, I'm confused about what happened at the end. At the end, Around 6:00-> I don't know how the Hydrogen that moved to the Tertiary Carbon can form a bond with the right carbon. And after, you move the Hydrogen tot he Tertiary Carbon, how can the ethanol get another hydrogen? Thanks! Sorry, I'm pretty bad at chemistry. T.T P.S Is the Hydrogen moving the same as 1,2 Shift?

[@mounikab8735]

Thank you so much sir, it's great and simple explanation and I have small doubt ,that is in the ethanol, why not it will eliminate the proton due to its electronegativity, and acts as strong acid as same as sodium methoxide in the E2 reaction??,thank you so much sir

[@ruata1719]

today, we have exam in chemsitry, This topic E1 was come, I asnwered base on this idea,.. It really helps me. thank you

[@riteshrk7336]

and now you are married 💍, time flies

[@ruata1719]

@@riteshrk7336 not yet. Thank you buddy. This is gold. 🥺👍✨⭐

[@RayBabol]

in america what age group would be learning about equations like these?

[@AmIsupposedToBeAlone]

Beautiful. I wish I had known about these videos when I was studying this in school :( I only just understood it now, as opposed to just memorising it.

[@MrFarkasOfficial]

would the bromine and ethanol then eventually combine at the end?

[@Jonathan-rf5cp]

Technically bromide and "ethanol cation", but if you extrapolate further, ethanol cation probably "loses" the H (in quotation marks because it may never really "gain" it in the first place) and the HBr is "formed" (formed in quotation marks because it would be soluble in ethanol and the ions are thus dissociated anyways).

[@quitejaded]

@NMLP1 I know I freakin' flipped my lid when I saw he had science videos. I was like "Oh sheeiiitttt, my GPA is saved after all!"

[@georgeofthejungle90]

does Sn1 also occurs ?

[@ambenton726]

What type of tablet do you use for your videos? I really want one!

[@nikos4677]

I dont understand why wouldnt the oxygen share its pair of electors with the carbocation?

[@OrcjaEnglish]

nice question

[@bilos1993]

Yes, HBr will be formed in the end and the alcohol will regenerate itself, so it is considered a catalyst in this reaction. There is also a small chance bromoethane will form and H2O will leave the molecule.

[@khayyam3000]

Thank You I was thinkin' the same thing. Like that H2O would probably leave the molecule......

[@Jonathan-rf5cp]

H+ would leave, in as much as it *can* leave (H+ cannot exist in solution by itself, so it would necessarily form the ethanol cation). HBr is kind of formed in that you essentially have HBr dissolved in ethanol at the end, but it isn't *really* formed because it wouldn't precipitate out.

[@khosrow]

@mrpimpyasian1 thats because he has so many degrees. he is also gifted.

[@bonbonpony]

08:40 And we also got a positively-charged product in (slightly) basic conditions, which is rather weird :q I see no reason why wouldn't that ethanol rather be more attracted by the positively-charged carbocation than the hydrogens surrounding it. Also the negatively-charged bromide might not be a very good base, but still a much better base than a neutral oxygen with its lone pair :q So I also don't see any reason why shouldn't it grab that hydrogen (if anyone could grab it at all, that is), since it's certainly better equipped to do so than the ethanol. Something seems to be wrong here, many things actually…

[@OmegaMinecraft4life]

If the step where the alcohol takes a hydrogen from the carbocation occurs doesn't that mean that the carbocation has to have a lower pka than a protonated alcohol? Which is lower than 0? That makes no sense to me!

[@mrpimp886]

How is he so knowledgeable and versatile? it seems to me he knows every subject field there is.

[@jyothi26rab]

Kindly help In the example 3 bromo 3 ethyl pentane i understood about bromine leaving the group and carbon being carbocation.carbon likes to form 4 bond as bromine left the Tertiary carbon making tertiary carbon shortage of one bond.How does the whole molecule become pre acidic. this question might come across as silly but i have to clear. to my understanding oxygen likes to grab electron why does oxygen grab electron from carbon which is next carbocation why it cannot take hydrogen from the ch3(far right)Lastly why oxygen cannot form a bond with carbocation why it has to grab hydrogen.kindly expalin

[@alkhorAHM]

Where is the line to blow this guy? Can't stress how helpful this is

[@thecoreybrown]

Great material and explanations but, there's no need to repeat what you say 2 or 3 times. Could probably cut the video time in half if you only said it once. Keep up the good work though!

[@nihayaturrohmah4230]

#35

[@RichBest8910]

What if We have NaOCH3 dissolved in CH3OH. I think we must have an E1 reaction then for sure, because of the strong base property of -OCH3. Can someone confirm or infirm ?

[@07794294114]

Can somebody explain why the SN1 reaction does not occur. I thought that only stong bases were able to be involved in elimination reactions as they are powerful enough to take the hydrogen from the carbon hydrogen bond which is very stable. Can somebody please answer my question.

[@junyangtan9962]

Is it possible that the ethanol's delta negative side get attracted to the carbocation and form a single bond with the carbon, producing a -ve charge on the oxygen. After which an extra electron on oxygen be given to the hydrogen to form H+ ion, forming a acid pair for the Br-. Please enlighten if possible. Thank you. A curious 17 year old who is trying to understand the basic of E1 reactions.

[@funkydiva12]

Singapore :)

[@bdnugget]

@Bio1993Hsapien SN is a nucleophillic attack, E is electrophillic

[@bonbonpony]

Nope, E stands for Elimination.

[@bdnugget]

@@bonbonpony yeah I was a noob 12 years ago lol

[@nida2192s]

19-22 y/o. ie. 3-4 year of college.

[@Nemoguzapomnit]

How come that oxygen got 3rd bond at 7:52 if oxygen can make only 2 bonds?

[@chachachan8138]

That's why it has a positive charge on it so it's probably unstable now

[@pravilpokharel2224]

Keep it up! :)

[@MutantNinjaFly]

I don't understand why the oxygen would take a positive charge. It is so electronegative, wouldn't it be much more stable with a negative charge, how would the more electronegative oxygen be more stable as a cation than the less electronegative carbon?

[@kaylahjames]

he talks sooooooooooo much dude 1.25 speed to hurry this lesson up lma o

[@johnmandrake8829]

2x man always 2x

[@ahmed-pc7ev]

I agree he has some kind of turbo in his throat. He doesnt come to the point. This is actually easy but he complicates it a lot by talking so much

[@SwarnimArun]

2.5x dude..

[@kye4355]

@@ahmed-pc7ev khan videos are generally meant for you to understand a concept initially. In other words, these videos are for those who have never seen an E1 reaction and want to know why it works. If you are looking for a quick review without as much explanation, organic chem tutor is the way to go imo

[@RayBabol]

so weird because in England we learn these at 16... not fair!

[@noflexzone2.055]

Same in some places in America....

[@Lolo-tg2cd]

why is E1 preferred over SN1?

[@ktvkieran]

+Lolo I believe that what happens is that they happen at the same time, depending on the reactants. So E1 will happen, but so will SN1, just in different proportions.

[@venusjain5591]

Lolo weak bases prefer e1

[@funkydiva12]

i wanna know tooooo. i'm 17 and learning this :/

[@FjNarutoFj]

I love these videos, they are so insightful! But I sometimes can't handle when he repeats the same phrase three or four times. That might make me a bad person.

[@nida2192s]

where are u from then?

[@makersdude8]

I LOVE YOU

[@fraddi]

Neutral Br has 3 valence electrons not 7

[@bachansingh7586]

tomorrow is my exam and I am gonna rock it. thanks for explaining so nicely

[@funzoclock]

If you were a nucleophile and I was the substrate, I would definitely let you attack me xD

[@NMLP1]

oh...my...GOD! i knew you had calc and diff eq videos... but WHAT THE FUCK!!! ochem now?!?!?!? i love you. i fucking LOVE YOU! jesus. your videos have saved my stupid ass so many times hahaha. wait wait wait.... okay serious compliment here. the main difference between you and my professors is that you slow things down so that students can understand. you kick ass mayneeee =P keep up the awesome videos

[@fraddi]

@RoflCopter58 He was just looking to make a chemical reaction...

[@chatlanikaran]

@07794294114 SN1 doesn't occur because the conditions require for the E1 reaction is heat plus the lone pair. E1 is favored at higher temperatures because it forms the strong C=C double bond which is more favorable than the OH.

[@fraddi]

@fraddi oops i was thinking Boron, stupid me!

[@NMLP1]

oh...my...GOD! i knew you had calc and diff eq videos... but WHAT THE FUCK!!! ochem now?!?!?!? i love you. i fucking LOVE YOU! jesus. your videos have saved my stupid ass so many times hahaha

[@silicon179]

what is the final product??

[@icrack96]

+Si_14 3-ethyl-3-pentene + Br^- + H2OCH2CH3.correct me if im wrong.

[@siddheshchavan9376]

i am also si 14

[@pbusmc69]

Who's here from Dr. Killways class?? O chem rocks!

[@Regista_06]

The name of the reactant molecule is actually, 3-Bromo 3-Ethyl Hexane.

[@vineetmadishetty6084]

COME TO OUR PARTY AT HEDGES U DONT WANT TO MISS THIS!!!! HIT UP A BROTHER FOR DETAILS

[@deepakk70]

y cant sn1 ocur here sirr??>.. .........................

[@BarragePker6]

+kumar jaganathan Mainly because in the reaction you are dealing with a weak nucleophile I believe.

[@fraddi]

@fraddi oops i think i made a mistake

[@LuvDatFilms]

fiiiiiiiiiiiiiiiiiiiiiirst lol