Comments on: Wittig Reaction https://www.masterorganicchemistry.com/2018/02/06/wittig-reaction/ Thu, 13 Jun 2024 09:05:39 +0000 hourly 1 https://wordpress.org/?v=6.6.2 By: Madhav Mittal https://www.masterorganicchemistry.com/2018/02/06/wittig-reaction/#comment-696577 Thu, 13 Jun 2024 09:05:39 +0000 https://www.masterorganicchemistry.com/?p=11307#comment-696577 Is sulfur ylides, (quiz id 0040), should not the sulfur bear the negative charge, being larger in size and slightly more electronegative than carbon?

]]>
By: Madhav Mittal https://www.masterorganicchemistry.com/2018/02/06/wittig-reaction/#comment-696504 Wed, 12 Jun 2024 13:26:09 +0000 https://www.masterorganicchemistry.com/?p=11307#comment-696504 Would PH3 or PCl3 work here inplace of PPh3?

]]>
By: James Ashenhurst https://www.masterorganicchemistry.com/2018/02/06/wittig-reaction/#comment-636780 Wed, 31 Aug 2022 14:16:29 +0000 https://www.masterorganicchemistry.com/?p=11307#comment-636780 In reply to m610105009@tmu.edu.tw.

Yes, the acetal is fairly easily removed by aqueous acid. I realize when you’re learning organic chemistry, textbooks can be fairly careless about H3O+. It can be used for hydration of alkenes, hydrolysis of acetals, or simple workup of a basic solution (e.g. Grignard reaction), but you’re not really given any gauge on the relative reactivity of any of these processes.

In practice it takes a pretty concentrated acid to hydrate the alkene, whereas a dimethyl acetal is readily hydrolyzed with H3O+. I suppose for a situation like this it might make it better to say, “mild acid?”. If it were “concentrated H2SO4, H2O” then I would see hydration as a significant process.

]]>
By: m610105009@tmu.edu.tw https://www.masterorganicchemistry.com/2018/02/06/wittig-reaction/#comment-636753 Wed, 31 Aug 2022 08:58:14 +0000 https://www.masterorganicchemistry.com/?p=11307#comment-636753 Hi ! I am confused by the quiz about the acetal protecting group, so the H3O+ only removed the mask of aldehyde group? Would the H3O+ do the acid catalyzed hydration on the alkenes outside the benzene or they are stable because of the conjugation with benzene so they won’t react with H3O+? Thanks

]]>
By: James Ashenhurst https://www.masterorganicchemistry.com/2018/02/06/wittig-reaction/#comment-635591 Thu, 18 Aug 2022 14:31:59 +0000 https://www.masterorganicchemistry.com/?p=11307#comment-635591 In reply to Pesv.

Noted. Thanks for the suggestion.

]]>
By: James Ashenhurst https://www.masterorganicchemistry.com/2018/02/06/wittig-reaction/#comment-635590 Thu, 18 Aug 2022 14:31:26 +0000 https://www.masterorganicchemistry.com/?p=11307#comment-635590 In reply to Faiz Ahmad.

No, because it isn’t possible to form the ylide if there are no C-H bonds on the carbon attached to the P.

]]>
By: James Ashenhurst https://www.masterorganicchemistry.com/2018/02/06/wittig-reaction/#comment-635589 Thu, 18 Aug 2022 14:30:13 +0000 https://www.masterorganicchemistry.com/?p=11307#comment-635589 In reply to Satvik.

Generally esters don’t react with ylides. To form a new =CH2 bond with the C=O of the ester you’d have to use something like the Tebbe reagent.

]]>
By: James Ashenhurst https://www.masterorganicchemistry.com/2018/02/06/wittig-reaction/#comment-635588 Thu, 18 Aug 2022 14:29:27 +0000 https://www.masterorganicchemistry.com/?p=11307#comment-635588 In reply to Park Kim.

That’s a good question. I usually see the other way around – a carbene reacting with a heteroatom to give an ylide.
There might be a pathway there. It would be a good research project.

]]>
By: Pesv https://www.masterorganicchemistry.com/2018/02/06/wittig-reaction/#comment-618895 Wed, 19 Jan 2022 17:38:40 +0000 https://www.masterorganicchemistry.com/?p=11307#comment-618895 Hi, love the explanations but would’ve been a tad nice to see the mechanism of the intramolecular wittig reaction:) Tried it out anyways, but can’t really check if it’s right – have tried google, but yeah, just wasn’t sure in what order the bromid would fall off and such.

]]>
By: Faiz Ahmad https://www.masterorganicchemistry.com/2018/02/06/wittig-reaction/#comment-612133 Wed, 10 Nov 2021 13:37:54 +0000 https://www.masterorganicchemistry.com/?p=11307#comment-612133 Hello James! Does 3° alkyl halide also show Wittig reaction.

]]>