Tutor.com Organic Chemistry Session

Dec. 5, 2013

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Session Transcript - Science - Chemistry, 12/1/2013 6:32PM - Tutor.comSession Date: 12/1/2013 6:32PM
Length: 37 minute(s)
Subject: Science - Chemistry


System Message
[00:00:00] *** Please note: All sessions are recorded for quality control. ***

Guest (Customer)
[00:00:03] ochem: SN1/SN2/E1/E2 rxns

Adrienne A (Tutor)
[00:00:18] HI there! Welcome to tutor.com !
[00:00:29] Unfortunately my knowledge of organic reactions is very limited.
[00:00:41] Would it be ok if I transfer you to another tutor who could be of more help?

Guest (Customer)
[00:01:15] yes

Adrienne A (Tutor)
[00:01:34] Ok so sorry about that! Hold on...

System Message
[00:02:06] *** The session has been transferred. ***

Kendra N (Tutor)
[00:02:40] Hi! Organic huh? What can I help you with?
[00:03:42] Is i general definitions, or do you have a specific problem you're working on?
[00:04:30] Are you still there?
[00:05:10] I'll only be able to wait for a few more minutes. If I don't hear from you soon, I'll need to end this session so I can help other students. You can sign back in when you are ready to continue working.

Guest (Customer)
[00:05:29] Hi

Kendra N (Tutor)
[00:05:45] Oh great! Hi, I'm Kendra

Guest (Customer)
[00:06:04] File Shared > Capture.JPG
[00:06:08] Hi
[00:06:10] :)

Kendra N (Tutor)
[00:06:56] Got it. So you've been doing substitutions and eliminations. Sound familiar?
[00:08:14] Can you tell me what is the leaving group in this problem?

Guest (Customer)
[00:09:32] Yes
[00:09:38] I am thinking that this one is E1
[00:09:43] b/c it is a strong base
[00:09:50] aprotic solvent
[00:09:54] and has heat?A

Kendra N (Tutor)
[00:10:04] It is a strong base, but also a good nucleophile...

Guest (Customer)
[00:10:09] I know my teacher said something about how I cannot always assume heat and whatnot.

Kendra N (Tutor)
[00:10:20] Why don't we take it one step at a time.

Guest (Customer)
[00:10:32] BUt we always have to look at the condition of whether or not it is a strong or weak nucleophile right?

Kendra N (Tutor)
[00:10:45] Yep, true.
[00:11:15] DMSO is aprotic, but the dielectric constant is high, which favors...?
[00:13:06] Sn2
[00:13:47] So looking at your problem, we have some conflicting evidence (pretty common)
[00:14:12] What would be the product of an E1 reaction?

Guest (Customer)
[00:14:28] Oh!
[00:14:37] So how about if I didn't know the dielectric constant
[00:14:42] what would I have to know?

Kendra N (Tutor)
[00:15:52] That DMSO solvates cations almost as well as water (ie, stabilizes the cation), and encourages the base to act as a nucleophile
[00:16:25] Did that make sense?

Guest (Customer)
[00:17:49] Oh okay

Kendra N (Tutor)
[00:17:59] Let's see if we can eliminate some of the answers.
[00:18:36] What would be the product of your E1?

Guest (Customer)
[00:18:42] Hmm

Kendra N (Tutor)
[00:19:56] There are two possibles... let's call them A, B, C, D and E, going from the top. WHich two are elimination products?

Guest (Customer)
[00:20:20] an R-OH right?
[00:20:32] alcohol
[00:20:33] haha

Kendra N (Tutor)
[00:21:21] The E stands for elimination, which means the leaving group is eliminated (not replaced) in the molecule.
[00:21:40] Which is the leaving group in you starting material?

Guest (Customer)
[00:21:54] X
[00:22:02] so the halogen group leaves

Kendra N (Tutor)
[00:22:28] Right. So if X is "eliminate", which two are possible products?
[00:22:41] Of the answers you are given.

Guest (Customer)
[00:23:17] and E follows zaitsev
[00:23:33] so it would be fourth choice given

Kendra N (Tutor)
[00:23:51] Yes!
[00:24:09] Well done. Now what if it were a substitution instead?

Guest (Customer)
[00:25:10] then first choice

Kendra N (Tutor)
[00:26:26] Tell me why?

Guest (Customer)
[00:27:12] because
[00:27:16] an ether group is formed
[00:27:22] Well
[00:27:23] okay

Kendra N (Tutor)
[00:27:31] You're right for SN2, I just want to hear you explain why that ether?

Guest (Customer)
[00:27:31] this rxn would go SN2 without heat
[00:27:36] But I'm not sure what heat would do to the rxn

Kendra N (Tutor)
[00:27:45] You are exactly right.
[00:28:00] The heat pushes us to expect elimination.
[00:28:39] Since you are not told what the leaving group acually is.
[00:29:30] It's probably safe to assume the heat wins over CH3O- as a nucleophile.
[00:30:44] Are you satisfied with what we covered? I would be happy to go over the SN2 product (s) with you

Guest (Customer)
[00:31:00] SO this would be SN2?

Kendra N (Tutor)
[00:31:17] No, I don't think so.
[00:32:31] The question asks for the major product, so the 4th compound is the right answer, but it could still be worth ooking at what the other products would be if you are interested.
[00:34:02] Otherwise, is there anything else I can help you with tonight?

Guest (Customer)
[00:35:00] So it would be E1?

Kendra N (Tutor)
[00:35:22] Primarily, yes. Do you have any questions about anything we went over today?

Guest (Customer)
[00:36:43] Nope
[00:36:44] Thanks!"

Kendra N (Tutor)
[00:37:05] Ok! Thanks for using Tutor.com. Please fill out the survey as you leave so we can learn how we can better help you in the future!