Sciencemadness Discussion Board
Not logged in [Login ]
Search the forums Search   Frequently Asked Questions FAQ   View member list Member List   Today's Posts Today's Posts   Forum Stats Stats Back to: sciencemadness.org
Sciencemadness Discussion Board » Fundamentals » Organic Chemistry » Removal of aldehyde from alcohol Go To Bottom

Printable Version  
Author: Subject: Removal of aldehyde from alcohol
DraconicAcid
International Hazard
*****



Posts: 4278
Registered: 1-2-2013
Location: The tiniest college campus ever....
Member Is Offline

Mood: Semi-victorious.

[*] posted on 14-11-2019 at 18:26
Removal of aldehyde from alcohol

I made some cinnamyl alcohol recently, and wanted to get rid of any excess cinnamaldehyde. Recrystallization is tricky because of its low, low melting point (I managed to get it to crystallize from toluene/heptane in an ace bath, but then the crystals melted at RT and gave two layers- cinnamyl alcohol and heptane).

So I'm planning to get rid of excess cinnamaldehyde by making the sulphite addition product. Should I a) dissolve the crude alcohol in toluene, and wash several times with sulphite solution, or b) dissolve the crude alcohol in methanol, add sulphite, filter out the adduct, then re-isolate the alcohol?

Most of the references I can find are for purifying the desired aldehyde, rather than removing it as an unwanted impurity.

(The alcohol smells nice, though- most of the people I've shown it to detect a floral or rosy odour, with hints of cinnamon, although one person insisted it smelled like hot dog water.)



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.
View user's profile View All Posts By User
DraconicAcid
International Hazard
*****



Posts: 4278
Registered: 1-2-2013
Location: The tiniest college campus ever....
Member Is Offline

Mood: Semi-victorious.

[*] posted on 14-11-2019 at 18:37


Never mind- found a reference. Wash organic layer with sulphite solution.

http://web.fscj.edu/milczanowski/eleven/cinnamin.pdf



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.
View user's profile View All Posts By User
nimgoldman
Hazard to Others
***



Posts: 303
Registered: 11-6-2018
Member Is Offline


[*] posted on 20-11-2019 at 09:40


Yes - remove alcohol by distillation, mix with sat. aq. bisulfite soln. (adduct will form), filter, wash with DCM or chloroform, evap. solvent, hydrolyze with dilute HCl, extract, dry solvent, filter, evap. solvent, vacuum distill
View user's profile View All Posts By User
Texium
Administrator
********



Posts: 4508
Registered: 11-1-2014
Location: Salt Lake City
Member Is Offline

Mood: PhD candidate!

[*] posted on 20-11-2019 at 10:39


Alternately, just run it through a short chromatography column. Cinnamaldehyde should elute much faster than cinnamyl alcohol. It would be a trivial separation.



Come check out the Official Sciencemadness Wiki
They're not really active right now, but here's my YouTube channel and my blog.
View user's profile Visit user's homepage View All Posts By User
Corrosive Joeseph
National Hazard
****



Posts: 915
Registered: 17-5-2015
Location: The Other Place
Member Is Offline

Mood: Cyclic

[*] posted on 20-11-2019 at 10:58


There is some interesting information in this old paper....

Hill, A. J., & Nason, E. H. (1924).
The Utilization Of Cassia Oil For The Synthesis Of Cinnamyl Alcohol.
Journal of the American Chemical Society, 46(10), 2236–2246.
https://sci-hub.se/10.1021/ja01675a014


/CJ



Being well adjusted to a sick society is no measure of one's mental health
View user's profile View All Posts By User
DraconicAcid
International Hazard
*****



Posts: 4278
Registered: 1-2-2013
Location: The tiniest college campus ever....
Member Is Offline

Mood: Semi-victorious.

[*] posted on 21-11-2019 at 17:28


Quote: Originally posted by nimgoldman  
Yes - remove alcohol by distillation, mix with sat. aq. bisulfite soln. (adduct will form), filter, wash with DCM or chloroform, evap. solvent, hydrolyze with dilute HCl, extract, dry solvent, filter, evap. solvent, vacuum distill


I'm not trying to save the aldehyde, just get rid of it from the alcohol I'm trying to purify. Distillation isn't an option because the bp is too high (and I don't have a pump for vacuum distillation).

Recrystallization seems to improve it a bit, but it still melts after the collected solid returns to room temp (even after washing with sodium bisulphite). I'll have to run a column.



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.
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 21-11-2019 at 18:50


Did you dry before evaporating? Maybe it's just a little wet.



"You're going to be all right, kid...Everything's under control." Yossarian, to Snowden
View user's profile Visit user's homepage View All Posts By User
DraconicAcid
International Hazard
*****



Posts: 4278
Registered: 1-2-2013
Location: The tiniest college campus ever....
Member Is Offline

Mood: Semi-victorious.

[*] posted on 21-11-2019 at 20:51


Quote: Originally posted by S.C. Wack  
Did you dry before evaporating? Maybe it's just a little wet.


Yes, over anhydrous sodium sulphate, twice (dissolved in toluene, which has a low affinity for water anyway).



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.
View user's profile View All Posts By User

 Sciencemadness Discussion Board » Fundamentals » Organic Chemistry » Removal of aldehyde from alcohol   Go To Top