Sciencemadness Discussion Board
Not logged in [Login ]
Go To Bottom

Printable Version  
Author: Subject: After RXN how to extract aldehyde
spanner
Harmless
*




Posts: 22
Registered: 5-7-2006
Member Is Offline

Mood: No Mood

[*] posted on 19-9-2006 at 04:00
After RXN how to extract aldehyde


i have just finished a Rxn of converting piperic acid to piperanol via CUSO4 redox can anyone help me in understanding how to now remove the aldeyde from the reaction flask and purifying it
View user's profile View All Posts By User
solo
International Hazard
*****




Posts: 3975
Registered: 9-12-2002
Location: Estados Unidos de La Republica Mexicana
Member Is Offline

Mood: ....getting old and drowning in a sea of knowledge

[*] posted on 19-9-2006 at 04:41


You might try using the search engine , had you done so you might have found the thread that talks about that particular problem with the reaction.......solo

http://www.sciencemadness.org/talk/viewthread.php?tid=4465




It's better to die on your feet, than live on your knees....Emiliano Zapata.
View user's profile View All Posts By User
spanner
Harmless
*




Posts: 22
Registered: 5-7-2006
Member Is Offline

Mood: No Mood

[*] posted on 20-9-2006 at 04:39


i did use the serch engine but if you read my question properly i was asking if anyone could help me to understand the process not just find the process because last i looked it just tells you which process to use
View user's profile View All Posts By User
not_important
International Hazard
*****




Posts: 3873
Registered: 21-7-2006
Member Is Offline

Mood: No Mood

[*] posted on 20-9-2006 at 07:17


Quote:
Originally posted by spanner
i have just finished a Rxn of converting piperic acid to piperanol via CUSO4 redox can anyone help me in understanding how to now remove the aldeyde from the reaction flask and purifying it


That doesn't sound too much more than asking for cookbook information.

You should have been ready to run product isolation right away, aldehydes tend not to stick around when there's air and/or acids or bases around.

The write-up in the reference give says to filter, wash copper oxide with water, add wash water to filtrate - thus removing the reacted copper from the mixture, then acidify and extract with ether to remove the organics from the reaction mix. Finally form the bisulfite addition product to isolate the aldehyde from unreacted raw material and any carboxylic acid formed through over- or air oxydation. Bisulfite addition compounds are likely talked about in other threads, as well as in many preparative org chem books - check those in the Library section.

The thread also had an entry saying
Quote:
The CuO procedure does not work as published on substrates having no phenolic group in my experience. Maybe it is because you need the Phenolate anion in solution which is oxidised by the CuO.
so your yield may be poor to none.

So what is lacking in the write-up in that thread, that you wish was there? It's typical technical journal reporting, targetted at readers with experience in the field. Lab textbooks are better for a 'how and why' explanation, teaching general technique although perhaps not using the exact reaction you are interested in.
View user's profile View All Posts By User
chochu3
Hazard to Others
***




Posts: 185
Registered: 21-10-2003
Location: South Side Tejas [Cloverland]
Member Is Offline

Mood: Inside looking out

[*] posted on 21-9-2006 at 02:33


sodium iodide I think can make a salt from an aldehyde. This may be found in Vogel's Pratical Chemistry.



\"Abiding in the midst of ignorance, thinking themselves wise and learned, fools go aimlessly hither and thither, like blind led by the blind.\" - Katha Upanishad
View user's profile View All Posts By User
spanner
Harmless
*




Posts: 22
Registered: 5-7-2006
Member Is Offline

Mood: No Mood

[*] posted on 22-9-2006 at 00:15


thanks guys that was a lot more helpfull, i start uni next year so im sure this will only get easier for me as i gain more knowledge and i hope that i can pass it on some day
View user's profile View All Posts By User
mick
Hazard to Others
***




Posts: 338
Registered: 3-10-2003
Member Is Offline

Mood: No Mood

[*] posted on 23-9-2006 at 11:15


The sodium bisulphate addition compound was good for separating aldehydes.
mick
View user's profile View All Posts By User
not_important
International Hazard
*****




Posts: 3873
Registered: 21-7-2006
Member Is Offline

Mood: No Mood

[*] posted on 23-9-2006 at 21:33


Quote:
Originally posted by mick
The sodium bisulphate addition compound was good for separating aldehydes.
mick


bisulfite, not bisulfate. I've mistyped that one myself.
View user's profile View All Posts By User
spanner
Harmless
*




Posts: 22
Registered: 5-7-2006
Member Is Offline

Mood: No Mood

[*] posted on 24-9-2006 at 02:20


Would it possible set up a distillation in stead of a reflux and distill the aldeyde off as its being formed then do a bisulfite purification after
View user's profile View All Posts By User
S.C. Wack
bibliomaster
*****




Posts: 2419
Registered: 7-5-2004
Location: Cornworld, Central USA
Member Is Offline

Mood: Enhanced

[*] posted on 24-9-2006 at 03:00


The solubility of piperonal in water decreases dramatically with decreasing temperature. One may find that it crystallizes out if left undisturbed for a while in the fridge if they actually have more than a smell. It sublimes easily, this is likely the best purification method for it.
View user's profile Visit user's homepage View All Posts By User
spanner
Harmless
*




Posts: 22
Registered: 5-7-2006
Member Is Offline

Mood: No Mood

[*] posted on 26-9-2006 at 02:16


I do seem to get that sweet marshmallow smell after the Rxn . I also am left with after the filtration step a clear yellow liquid, if i leave it for a little while a white precipitate forms but has a high m.p so i assume that cant be the piperanol i think i may try the distillation and see if distilling while the Rxn progresses ill let you know how it goes
any more help appreciated
View user's profile View All Posts By User

  Go To Top