Formation of chlorohydrins from alkenes using water and Cl2
Description: Alkenes treated with chlorine (Cl2) in the presence of water will form chlorohydrins. The stereochemistry of the products is anti.
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Org. Synth. 1953, 33, 15
DOI Link: 10.15227/orgsyn.033.0015
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In the step 2, why does H2O attack not chloride ion? isn’t chloride ion more nucleophile than water? Thanks.
Because water is solvent (or co-solvent) and vastly outnumbers the amount of chloride ion.
Hi!
In the 3rd reaction, why wouldn’t a 6 membered ring get formed?…like with chlorine on the ring?
Great question. In general formation of 5-membered rings is about 10 times faster than formation of 6-membered rings.
See: https://en.wikipedia.org/wiki/Baldwin%27s_rules#:~:text=Baldwin's%20rules%20in%20organic%20chemistry,closures%20of%20these%20various%20types.
hi , in the 3rd reaction , i checked the mechanism , based on what you choose the intra OH to attack instead of water ? thank you :)
Intramolecular reactions are generally faster than intermolecular reactions, especially if you’re forming a 5 or 6 membered ring.
In the third example, why doesn’t a six-member ring form?
Great question. In general, formation of 5-membered rings is about 10 times faster than formation of 6-membered rings.
https://en.wikipedia.org/wiki/Baldwin%27s_rules#:~:text=Baldwin's%20rules%20in%20organic%20chemistry,closures%20of%20these%20various%20types.
it is a *chloronium ion, not a bromonium ion, correct? just a typo, but worth fixing :)
yes, thank you! Fixed.
could you by any chance explain the mechanism of the 3 rxn? trying to get it and I’m not sure if the water that just attacked leaves or if the HCl adds an H to the other OH and then that leaves
Agree – the mechanism of the 3rd rxn is not clear
I drew a picture of the mechanism of this reaction, see here: http://imgur.com/ybbrTim
Hi,
according to the mechanism drawn, should the reaction also happen without water? Chloride can act as a base in that case.
Thank you for that, James.
Numbering the carbons will help
MarkovnikoV*
I use both misspellings of the name. : – )
what is the mechanism of the last reaction
The mechanism is exactly the same, except the oxygen is attached to the rest of the molecule.