Timeline for Formation of enamine for unsymmetrical cyclohexanone derivatives
Current License: CC BY-SA 4.0
20 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Jul 13, 2021 at 6:37 | comment | added | napstablook | @Waylander I agree, I still think it should be mentioned though. | |
| Jul 12, 2021 at 16:06 | history | became hot network question | |||
| Jul 12, 2021 at 10:43 | vote | accept | TRC | ||
| Jul 12, 2021 at 10:37 | answer | added | Waylander | timeline score: 6 | |
| Jul 12, 2021 at 10:27 | comment | added | TRC | @Waylander Yes, the enamine does get hydrolyzed when $\ce{H3O^+}$ is added - that's why the options again depict cyclohexanone. As for the concentration and temperature, that's another fault of this exam - they give us only half the experimental information and expect us to know what products will be formed. | |
| Jul 12, 2021 at 10:24 | comment | added | Waylander | @napstablook the H+ will hydrolyse the enamine very much more easily than the nitrile. Mild aq acid at rt hydrolyses enamines, you need forcing conditions (conc acid, high temp) to hydrolyse nitriles. It is entirely possible to be selective about which group is hydrolysed. | |
| Jul 12, 2021 at 9:19 | comment | added | TRC | @napstablook Absolutely agreed! It's not from a book though, it's from a coaching institute's mock test for a national level exam. I've found a lot of their other questions to be meaningless as well. | |
| Jul 12, 2021 at 9:18 | comment | added | Rishi | @napstablook True, it should have worked out if they had mentioned mild workup. | |
| Jul 12, 2021 at 9:16 | comment | added | napstablook | 1 last point, this is a really bad question, the h3o+ at the end will hydrolyse the cyanide. Usually if you have to question the author's intention more than think about the question it is not a good qn. :( | |
| Jul 12, 2021 at 9:15 | comment | added | TRC | @Rishi No, nothing. It has the same mechanism, just with the structures included. | |
| Jul 12, 2021 at 9:14 | comment | added | TRC | @Rishi I knew only strong bases (like NaOH or LDA) were sufficiently basic to remove the hydrogen from alpha-carbon. In the pathway you mention wouldn't the equilibrium lie largely to the reactant side? | |
| Jul 12, 2021 at 9:14 | comment | added | Rishi | @TRC you can put their mech in the post if it has other noticeable details else the post is fine as it is. | |
| Jul 12, 2021 at 9:12 | comment | added | TRC | @napstablook I just asked for the test paper's solutions from my teacher. I checked and it has the same mechanism as I suggested, only with the step 2 double bond formed on the other side. They have not mentioned any reason for that. | |
| Jul 12, 2021 at 9:12 | comment | added | Rishi | @TRC 1. Removal of acidic H by pyrrolidene from the less substituted alpha carbon then this Nu- reacts as you mentioned in step 3 and follows | |
| Jul 12, 2021 at 9:10 | comment | added | TRC | @Rishi I wasn't able to understand the other pathway you suggested. Where will the acidic H be removed from? | |
| Jul 12, 2021 at 9:08 | comment | added | TRC | @napstablook Thank you for your input. The cis-trans is probably referring to isomerism with respect to the cyclohexane ring. My main textbook uses that term to refer to groups around ring on same side or opposite sides (for example, as in 1,2-dimethylcyclohexane). Not sure if that term has become obsolete now or not. | |
| Jul 12, 2021 at 9:08 | comment | added | napstablook | @Rishi That's not really cis-trans though. I should have added db bond with cis/trans though | |
| Jul 12, 2021 at 9:05 | comment | added | Rishi | @TRC I can see 2 pathways for this reaction, one through additon reaction(in first step) other through removal of acidic H and my prof had taught, that in such condtions carry out acid base first as this reaction is faster. I also doubt whether acc to your mech dehydration would not happen, I might be wrong about this though. | |
| Jul 12, 2021 at 8:41 | comment | added | napstablook | I think the answer key is probably wrong (judging from the other options it seems like you really had to decide between the 2 enols really. $\alpha-H$ calculation makes it clear that we should prefer C. What is this cis-trans it is mentioning in opt. B and D? I don't see an stereogenic center.. | |
| Jul 12, 2021 at 7:57 | history | asked | TRC | CC BY-SA 4.0 |