Substitution and Elimination reactions are potentially the most difficult concepts covered at the Organic Chemistry 1 level. In addition to studying the SN1 SN2 E1 and E2 reaction mechanisms, you also have to understand the similarities and differences so that you can derive the correct products for specific reaction conditions.
I've put together this medium/tricky quiz to help you practice the reactions and gauge your level of comprehension.
Not fully confident yet? Go back and review my entire SN1 SN2 E1 E2 reaction video series and study the associated cheat sheet before getting started. So take your time as you go through the questions. If you get stuck just visit the video series page (linked above) and watch the related tutorial.
Download PDF Solutions posted at the end of the quiz.
Substitution Elimination Practice Problems
Question 1: Rank the following nucleophiles in order of increasing strength
Need help? Watch the Nucleophile vs Base videos in the series
Question 2: Arrange the following molecules in order of increasing reactivity/ability for a unimolecular elimination reaction. (E1)
Question 3: Arrange the following molecules in order of increasing reactivity to undergo a bimolecular substitution reaction (SN2)
Question 4: Which direction is favored at equilibrium when dissolved in an acetone solution? What about methanol?
Need help? see the solvents video in the series
Predict the product for each of the following reactions. Be sure to show stereochemistry when appropriate. Be sure to label major/minor products when more than one outcome is possible.
Question 5:
Question 6
Question 7
Question 8
Question 9
Question 10
Question 11
Question 12
Question 13
Question 14
Question 15
Question 16
Question 17
Question 18 Draw ALL possible starting haloalkanes that would form this product when undergoing unimolecular elimination.
Question 19: Show how to bring about the following transformation. You may use any reactants and reagents necessary
Question 20: Predict the product/s when (2R,3S) 3-ethyl-2-iodohexane reacts with NaSCH3 in dimethyl sulfoxide.
Question 21: Draw a complete mechanism for the following reaction. Be sure to include all intermediates, formal charges, and pushing arrows.
Bonus Question 22: Show how to bring about the following transformation. Hint: Pay attention to the orientation of substituents
Bonus Question 23: Show the complete mechanism for the following transformation. Hint: More than one reaction is required.
What did you think of this quiz? Easy? Hard? Need more practice?
Could you explain the reasoning behind the order for question #3? For an SN2 reaction, reactivity increases from methyl, to a primary, then a secondary, correct? Also, for question #2, although it’s an E1 this time, the reactivity still increases from methyl, to a primary, then a secondary.
For question 10, could you add the double bond to the other side since it is disubstituted instead of monosubstituted (following Zaitsev’s rule)?
Hello!
I was just wondering why, in question 11, only the E2 product was present, and not the SN2 as well since OH- is both a strong nucleophile and base.
Thanks!
First product would be the major product in question 17 as per your solution??
Do you have a hard quiz than this
Sorry, I’m a bit confused for qn 6 as well… why the SN2 product minor and the E2 product major?
Hi Leah, for question 2 why is it that branching at the beta carbon slows down the E1 reaction? Same for question 3, why does the branching slow down the SN2 reaction?
hi would you please let me know how can I check the answers with you
Thank you so much mam ❤️❤️for helping us without any reason
mam i cannot get these solution on email..is there is any other way in which i got these solution.
HI Leah
ques 20- why the ethyl isnt dash ? the iodo is number 1 than carbon3 is number 2 ,what makes it S. no?
Solutions are deleted? Can’t find em
I think the answer of number 11 is trans(E)-form, but not cis(Z)-form. From Newman projection, there are two products, and the transform is major product.
On #2, why does the secondary rank higher than the secondary to tertiary rearrangement?
Hi Leah,
Im a bit confused on how number 17 worked. Can you explain
Hi I don’t get the answeres via email
what is the major product in qn 17
In qn no. 11 product should be trans
Hello Leah, how can I get a better score for my next exam for organic chemistry which is going to be over Mechanism?Thanks
Hi Leah, thanks for the quiz! For number 12, wouldn’t it be and E2 and SN2 product, not just E2?
I don’t get answers
very nice examples…question 19 is confusing
Hi Leah, could you possibly explain question 12 and 13. How come its an E2 reaction only and not an SN2? And for 13 why are the methyls dissociated?
Thank you ever so much Leah.
Leah mam how could i get answers of above question?
Leah mam how could i get answers of above questions?
i like what you doing in organic chemistry it helps me alot to understand it.
can you explain question 8, how come there wasn’t a hydride shift ?
thx a lot but can you explain Q4 because in solutions u wrote the final answer without explanation??
So nice
Can I get the answers pliz
is it possible to draw out the mechanism on the solution? because I dont understand for #6 why E2 is a major product, #14 why is it E2 not Sn2, and, #15 I cannot follow how you got an oxolane product…
Why in question 7 does the cyanide group become equatorial? Shouldn’t it remain in the axial position?
The solutions don’t find in email? Why?
That is good.
Hello! I have a question about number 5, but I’m going to explain my process first:
Br is on a primary carbon, so it is either E2 or SN2
CH3O^- is a good base (I think)
E2 needs a good base, and we have one
HOWEVER, it goes through an SN2 because I can’t find a structure after an E2 that’s neutral… am I missing something or overthinking this?
Thank you for providing this recourse 🙂
resource*
Can you explain problem 17? No idea how you got that answer
For question 11, is it not an E1 reaction since its 3rd degree Leaving group? To which, if it is E1, it wouldn’t matter if the hydrogen was anti periplanar (anti coplanar).
Hi I can’t get the answers via email and I really need them
Why wouldn’t question 8 have two products because it is tertiary to would react via SN1, so would have cis and trans as products? (Answer key only has only product)
hi thanks so much for these! I just have a question about number 12, how come elimination is the major product? wouldn’t it be sn2 because its a strong base attacking a secondary carbocation?
Thank you
Hi Ms. Leah! The link in my e-mail isn’t working. Do you mind checking it again? 🙂
nvmd got it thanks!
Why is E2 favored in number 6 if its a strong nucleophile and will attack easily?
Hello, would you mind emailing me the solutions for the problems? i did not receive it even after signing up with two different emails.
BTW you are really helping me with those YouTube videos and cheat sheets. ugh my prof is a nightmare 🙁 .
I wish you mentioned what types of reaction ( Sn1, SN2, E1, or E2) each reaction went through in the answer section.
as i have exam on tuesday , i do not have so much time to answer each question by myself so i would be pleasant ,send me the solution of question.thank you so much.
hello Ms leah, thank you for uploading useful video.I need the solution of these problems because i feel some problem to solve them.
I also dont understand why in Q 22 there is no Hydrideshift so the + goes to the bridge Carbon and gives a tertiary C+ so OH is adding there.
Hi Leah, I dont understand why in Q1 CH3CO2H is weaker than CH3OH , I thought resonance makes the NU stronger?
Thank you so much Leah! <33
I do have a question though. Can you explain a bit about question no 4. Is it going to the left because iodide is a good leaving group (weak nucleophile as well) since it is in a polar aprotic solvent? while vice versa in polar protic solvent? Can I take it as that's the case?
Hey Leah, these problems are great. I have a question about the answer to problem 22. Wouldn’t Sn1 cause a hydrogen shift so that the carbocation could be on the more stable tertiary carbon? I did 2 Sn2 reactions in order to invert the stereochemistry instead. Could this be done?
Can you go over #15? I’m not sure how the intermolecular Sn2 works and how we create the ring
leah, those problems are fine. I will try them out. Hopefully I can get the solutions to compare with my answers
For number 10 why does the double bond form at the end? Would it not form between the two carbons rather than just the one?
I have an exam on this in 10 days, and I do not understand the material AT ALL, any suggestions on how to “cram” in order to pass this test? Thank you
I found this SOO helpful, thank you so much!!
What does “CONC” mean??
hello ! I can’t get the answers via email. Thank you in advance !
Hi Frida, if the solutions don’t come to the email you entered, try looking in the spam folder or maybe try entering in a different email.
Thank you so much mam
You’re welcome, Monish!
Why does reaction #10 produce an alkene monosubstitute? Would it not produce the Zaitsev product, the alkene disubstitute?
I m unable to get solutions..i filled the details but didnt receive the mail
Try signing up again
Ms. Leah, can you please explain number 1? Why is NaSCH3 stronger than NaOCH3? I watched your video again and again, but isn’t the answer different from protic to aprotic? If it is protic, Sulfur should be stronger than O but if aprotic, O is stronger than S? I am so confused…….does that question have to specify that or polar protic is given? Or am I not understanding something? And why is Carboxylic acid weaker than CH3OH?
I’m so lost… please help.
I don’t understand why you’re asking about solvent here Hoeun. S is a stronger nucleophile compared to O due to its larger size
i learned that a good nucleophile is small and negatively charged (oversimplifying) but still, i also listed O as a better nucleophile vs S given this question. Can you explain why larger is better?
I am confused too. We are mentioning the solvent because nucleophilicity differs in an aprotic solvent (same as basicity, the strength of the nucleophile increasing up the group or family) versus a protic solvent (opposite of basicity, the strength of the nucleophile decreasing down the group or family). It seems impossible to answer this question without mentioning the type of solvent, aprotic or protic.
I am confused by question 1. Nucleophilicity differs in a protic versus an aprotic solvent. In an aprotic solvent, nucelophilicity increases going down a column. In a protic solvent, nucleophilicity increases going up a column. Question 1 should state the solvent, but the given answer follows a polar protic solvent. Do you agree, Leah?
could i get the answer to these the email didn’t come
Email me Natalie
can someone explain me question 13?
Did you check the solutions Yossi?
For question 3, i got confused between 2,3. The double bond would not favor the SN2 reaction. Therefore, i thought the one without the double bond will be more reactive.
question 15 is quit tricky for me. I haven’t received the solutions yet so can anyone tell me how to go about it? How do you solve for the OH
Jay: Email me if you still haven’t received the solutions
Can I get the answers ,please?
Can I get the answers, please?
I’m not having the answers,can’t wait to see them….
If you signed up you should have received them within 5 minutes Enida
On question 1, how does NaSCH3 differ from CH3S? NaSCH3 should disassociate to Na+ and -SCH3. How come CH3S isn’t negatively charged?
Steven, Error on my part. thanks for pointing it out
Good Leah you are beautiful
why is question 20 not an E2 reaction?
negative sulfur makes a strong nucleophile but weak base. This means it prefers SN2 over E2. In addition, since the reaction takes place in a polar aprotic solvent, SN2 is favored once more over E2
i can’t open the quiz solutions easily, i can’t open the link. idk if i need to pay something or?
It’s free. Did you get the email?
Since there are 2 anticoplanar beta-hydrogens to choose from in question 6, wouldn’t we expect 4 elimination products? (i.e. the cis/trans isomers resulting from the double bond at both positions)
i do not understand why question Number 5 is an Sn2. the Nucleophile is strong but the solvent is polar and protic, which means Sn2 cannot happen, CH3O^- is a strong base so it will do E2, especially that the substrate is primary
It is not possible to form a pi bond on a primary benzyl carbon since the benzene ring is already maxed out with bonds and does not have a free hydrogen atom. This is a trick question because even though E2 would be most favorable the reaction proceeds SN2 as the less-likely but only possible option
This quiz was about medium difficulty. I took it once and didn’t understand it. I studied for many hours and now I find it to be a medium difficulty.
That’s awesome Michell. There are a few mistakes which I plan to correct shortly
These are really helpful and sums up all we learned in the boot camp
Thanks Leah!!!!
Thanks Danielle! Glad you found it helpful
Thank you so much Leah
Thank you Ahmed. did you find it easy or difficult?