thors.lab
Hazard to Others
Posts: 103
Registered: 19-7-2019
Member Is Offline
|
|
Amateur route from R-OH to R-Cl
As far as I know this reaction can be done with thionyl chloride or phosphorous trichloride, both of which are really hard to get and rather
dangerous. Are there are any amateur routes for this reaction?
|
|
|
DraconicAcid
International Hazard
Posts: 4355
Registered: 1-2-2013
Location: The tiniest college campus ever....
Member Is Offline
Mood: Semi-victorious.
|
|
Depends on the R group. A tertiary alcohol can usually be converted to a chloride just with cold concentrated HCl.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
|
|
|
Tsjerk
International Hazard
Posts: 3032
Registered: 20-4-2005
Location: Netherlands
Member Is Offline
Mood: Mood
|
|
Or benzyl alcohol, which is also easily converted with HCl.
|
|
|
teodor
National Hazard
Posts: 922
Registered: 28-6-2019
Location: Netherlands
Member Is Offline
|
|
HCl + ZnCl2 + reflux + good mixing also works for some primary and secondary alcohols.
|
|
|
thors.lab
Hazard to Others
Posts: 103
Registered: 19-7-2019
Member Is Offline
|
|
I was thinking primary or secondary alcohols.
|
|
|
thors.lab
Hazard to Others
Posts: 103
Registered: 19-7-2019
Member Is Offline
|
|
Due to resonance stabilization in Sn1 pathway I assume? Useful, but if we don't have the sn1 pathway available... what do we do?
|
|
|
Steam
Hazard to Others
Posts: 238
Registered: 25-3-2014
Location: Minnesota
Member Is Offline
Mood: Triple Point
|
|
Depending on what exactly you were working with you (if it obeyed Markovnikov or not) might be able to do an elimination reaction to form a alkene
then treat it with the acid to from your product. You can influence the outcome with the introduction of peroxides in the reaction (see peroxide
effect). If you provide a bit more information about what you are working with we could give more detailed answers.
Also for Benzyl alcohol, it is absolutely due to resonance stabilization. The reason is due to allylic carbon stabilization. Recognizing allylic
carbon is a really handy tool when working on synthesis schemes.
DISCLAIMER: The information in this post is provided for general informational purposes only and may not reflect the current law in your jurisdiction.
No information contained in this post should be construed as legal advice from the individual author, nor is it intended to be a substitute for legal
counsel on any subject matter. No reader of this post should act or refrain from acting on the basis of any information included in, or accessible
through, this post without seeking the appropriate legal or other professional advice on the particular facts and circumstances at issue from a lawyer
licensed in the recipient’s state, country or other appropriate licensing jurisdiction.
|
|
|
thors.lab
Hazard to Others
Posts: 103
Registered: 19-7-2019
Member Is Offline
|
|
For some — whats the criterion here? Looks appealing since ZnCl2 and HCl are no problem to get.
|
|
|
thors.lab
Hazard to Others
Posts: 103
Registered: 19-7-2019
Member Is Offline
|
|
Quote: Originally posted by Steam  | Depending on what exactly you were working with you (if it obeyed Markovnikov or not) might be able to do an elimination reaction to form a alkene
then treat it with the acid to from your product. You can influence the outcome with the introduction of peroxides in the reaction (see peroxide
effect). If you provide a bit more information about what you are working with we could give more detailed answers.
Also for Benzyl alcohol, it is absolutely due to resonance stabilization. The reason is due to allylic carbon stabilization. Recognizing allylic
carbon is a really handy tool when working on synthesis schemes. |
Thanks! I'm not working with any particular product here, this is theoretical. I've had to abandon ideas for projects in the past due to this problem
(can't recall any off the top of my head right now), so it would be nice to figure out a way around it.
|
|
|
teodor
National Hazard
Posts: 922
Registered: 28-6-2019
Location: Netherlands
Member Is Offline
|
|
Just look in Vogel's "Practical organic chemistry", "Alkyl Halides". I did this route for n-butyl chloride, sec-butyl chloride and iso-amyl chloride.
The yield of sec alcohol is very depending on mixing and is almost nothing without continuous vigorous (magnetic) stirring, because the mixture forms
2 layers. For n-butyl chloride I did it without any additional stirring.
Edit: also I changed the step "wash with NaOH" to "wash with NaHCO3". I was a bit puzzled why it was NaOH in the book.
[Edited on 27-10-2020 by teodor]
|
|
|
Tsjerk
International Hazard
Posts: 3032
Registered: 20-4-2005
Location: Netherlands
Member Is Offline
Mood: Mood
|
|
Bromides are usually easier to make with in situ HBr and the short chain bromides are easier to condens compared to the chlorides. Depending on what
you want to do with them the bromide might be worth considering.
|
|
|
Chemi Pharma
Hazard to Others
Posts: 350
Registered: 5-5-2016
Location: Latin America
Member Is Online
Mood: Quarantined
|
|
@Thors.lab, you can use also the TCCA/triphenyl phosphine route or use the cyanuric chloride/DMF route easily and with good yields. Papers attached.
Attachment: Alcohols to Chlorides with cyanuric chloride and DMF.pdf (54kB)
This file has been downloaded 332 times
Attachment: Alcohols to Alkyl Chlorides with TCCA and Triphenylphosphine.pdf (26kB)
This file has been downloaded 369 times
|
|
|
clearly_not_atara
International Hazard
Posts: 2799
Registered: 3-11-2013
Member Is Offline
Mood: Big
|
|
If the resulting alkyl chloride is soluble in water, you might be able to use an iodide (or bromide) salt catalyst, since I- is a stronger nucleophile
than Cl-, so performs the first Sn2 faster:
ROH2+ + I- >> RI + H2O
RI + Cl- <> RCl + I-
The second reaction is an equilibrium which usually weakly favors chloride but can be disrupted by solubility differences as in the Finkelstein
reaction. However, the equilibrium will not be established if the alkyl iodide is not soluble in water.
[Edited on 27-10-2020 by clearly_not_atara]
|
|
|
Corrosive Joeseph
National Hazard
Posts: 915
Registered: 17-5-2015
Location: The Other Place
Member Is Offline
Mood: Cyclic
|
|
https://tinyurl.com/yy4ynfhb
https://tinyurl.com/yydl9kjl
/CJ
Attachment: A Systematic Study of the Preparation of Alkyl Chlorides from the Corresponding Alcohols.pdf (512kB)
This file has been downloaded 382 times
Being well adjusted to a sick society is no measure of one's mental health
|
|
|
Cou
National Hazard
Posts: 958
Registered: 16-5-2013
Member Is Offline
Mood: Mad Scientist
|
|
Alkyl chlorides and alkyl bromides are often carcinogenic. Use gloves and a lab coat, a respirator with organic vapor cartridges, and a heavy duty
fan. Leave used glassware to sit outside for a day or two (to let alkyl halides evaporate) before bringing it inside for washing.
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
