dextro88
Hazard to Self
Posts: 60
Registered: 20-10-2018
Location: In the lab
Member Is Offline
Mood: loading...
|
|
Darzen condensation
Im researching the mechanism behind the darzen condensation,
the papers says also the para-substitued aldehydes gives even higher yields,
otherwise i was just want to confirm the procedure im going to do to be relaible :
1mole of aldehyde is combined with 1mole methyl-haloacid and driped over sodium methoxide in methanol, refluxing for a few hours afther full additon
and isolate the glycidic ester as sodium salt without the need of inert atmosphere in the reaction conditions and isolate it directly from the
reaction mixture as its quite insoluble as sodium salt in almost everythink as i understand ?
many thanks for any suggestions 
Best regards, dextro
[Edited on 17-6-2020 by dextro88]
|
|
|
stoichiometric_steve
National Hazard
Posts: 827
Registered: 14-12-2005
Member Is Offline
Mood: satyric
|
|
Again with the spoonfeeding?
|
|
|
dextro88
Hazard to Self
Posts: 60
Registered: 20-10-2018
Location: In the lab
Member Is Offline
Mood: loading...
|
|
sponfeeding ???
Im asking somethink chemistry related if someone want to give me some insight before experimentation to help me i will be greatfull, otherwise go with
spaming otherwhere, as in the serach engine isnt much of this topic i thinks its good to coment this procedure.
|
|
|
Tsjerk
International Hazard
Posts: 3032
Registered: 20-4-2005
Location: Netherlands
Member Is Offline
Mood: Mood
|
|
Start by giving a reference to the procedure you are talking about...
|
|
|
dextro88
Hazard to Self
Posts: 60
Registered: 20-10-2018
Location: In the lab
Member Is Offline
Mood: loading...
|
|
Im looking at this paper but its unclear when they perfom the darzen betwen haloacetic acid and 4chlorobenzaldehyde they use sodium and no
methanol/ethanol to form the ethoxide in suito and use toulene as solvent, there is also some theoretical speaking on the hive with theoretical
claimed succes by adding sodium methoxide in solution of methyl-haloacid and subst. benzaldehydes in toulene and extracting the sodium salt by adding
sodium as it must be quite insoluble in these reaction conditons and comes in reasonable purity, but im am not a chemist yet myself and want to
experiment and know exactly what i do.
best whishes, dextro
Attachment: Chapter 10- The Darzens Glycidic Ester Condensation - Newman and Megerlein (Org. Reactions V) (1949).pdf (527kB)
This file has been downloaded 1138 times
[Edited on 18-6-2020 by dextro88]
|
|
|
Tsjerk
International Hazard
Posts: 3032
Registered: 20-4-2005
Location: Netherlands
Member Is Offline
Mood: Mood
|
|
To be clear, they don't use halo-acetic acid. And why would you doubt this reference? Do you have reason to?
|
|
|
dextro88
Hazard to Self
Posts: 60
Registered: 20-10-2018
Location: In the lab
Member Is Offline
Mood: loading...
|
|
darzen catalyzed only by sodium ?
i wisly woud use the methoxide, and woud that change the procedure, it seems no-one is going to help me, so i probably will need to figure out the
best conditions duo to experimentation, it looks easy but as everybody know thinks sometimes only looks easy, im intrested how to determine the
glicidic ester have been formed and woud the sodium salt can be dicretly extracted into alkaline solution and woud it left in the fridge with the
exess alkaline precipitate ?
[Edited on 18-6-2020 by dextro88]
|
|
|
Sigmatropic
Hazard to Others
Posts: 307
Registered: 29-1-2017
Member Is Offline
Mood: No Mood
|
|
I fail to see how the glycidic ester can form a sodium salt.
|
|
|
dextro88
Hazard to Self
Posts: 60
Registered: 20-10-2018
Location: In the lab
Member Is Offline
Mood: loading...
|
|
its shoud do,i will post a refference that can be trust like grain of salt...(https://the-hive.archive.erowid.org/forum/showflat/Cat-/Numb...) in wich barium even used exess methyl-halopropionate instead like in the patent
stating 1:1 molar ratio, probably its water soluble but in toulene/methanol reaction conditions it shoud precipitate in the fridge for shure, but i
will probably need to neutralize the reaction mixture with alkaline solution, and its no matter for me to isolate it as pure glyicidic ester or as the
sodium salt even in alkaline solution, im looking for the best way to isolate it from the reaction mixture that dont need distilation, and probably
the crude salt will need some sort recrystalization, its my first time working with glycidic esters or theyrs salts, so any help will be very
apreciatable.
Sincerly, dextro
[Edited on 19-6-2020 by dextro88]
|
|
|
stoichiometric_steve
National Hazard
Posts: 827
Registered: 14-12-2005
Member Is Offline
Mood: satyric
|
|
yeah well good luck with your low effort crap.
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
