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

Printable Version  
Author: Subject: Cold and Minty
Aloesci
Harmless
*




Posts: 28
Registered: 7-4-2018
Member Is Offline

Mood: No Mood

[*] posted on 2-3-2021 at 03:18
Cold and Minty


I'm experimenting with making some menthol crystals from peppermint oil I've distilled.
Industrially, they freeze the oil colder than around -22.2°C where the menthol crystallises out.

My first idea to reach this temperature was an salt and ice bath but apparently those only get to about -21°C
Then I thought of using butane from a canister to cool it down but butane boils at -1°C so that wouldn't work either.

What could be some easily obtainable and effective options for cooling below -22.2°C? Or even a lot colder?
View user's profile View All Posts By User
Antigua
Hazard to Others
***




Posts: 116
Registered: 27-9-2020
Member Is Offline


[*] posted on 2-3-2021 at 03:21


CaCl2 + ice gets lower than -35 if I recall correctly. Just toss some CaCl2 with ice and add a bit of water to slush it up and put in your freezer. Or buy dry ice.
View user's profile View All Posts By User
Fyndium
International Hazard
*****




Posts: 1013
Registered: 12-7-2020
Location: Not in USA
Member Is Offline


[*] posted on 2-3-2021 at 09:04


About 30% CaCl2 can go even as low as -54C, at least in theory. In practice, I've got currently a polyurethane box of 20 liters filled with CaCl2 solution sitting in a chest freezer at -35C and it's fully liquid and clear. I use it as cold trap coolant primarily, and for specific reactions, because dry ice is exceedingly expensive.
View user's profile View All Posts By User
mackolol
National Hazard
****




Posts: 437
Registered: 26-10-2017
Location: Poland
Member Is Offline

Mood: Psychedelic

[*] posted on 2-3-2021 at 10:34


Keep in mind, that the CaCl2 has to bee in form of hydrate to create the -35C solution with ice.
Also, you can use dry ice + acetone solution as mentioned if you have dry ice on hand
View user's profile View All Posts By User
Fery
International Hazard
*****




Posts: 503
Registered: 27-8-2019
Location: Czechoslovakia
Member Is Offline


[*] posted on 2-3-2021 at 10:55


After crystallization, you'll obtain an oil depleted of menthol, but there is still a lot of menthol present from which it could be separated by vacuum distillation using powerful column.
https://www.sciencemadness.org/whisper/viewthread.php?tid=15...




If there is a heaven, it seems not to be materially based. Does chemistry exist there and if yes, how does it look like? Are there good souls well supplied with laboratory equipment, glass, chemicals and information?
View user's profile Visit user's homepage View All Posts By User
unionised
International Hazard
*****




Posts: 4626
Registered: 1-11-2003
Location: UK
Member Is Offline

Mood: No Mood

[*] posted on 2-3-2021 at 11:23


Looking at that paper I wonder if reduction of the peppermint oil with borohydride before fractionation would increase the menthol yield.
View user's profile View All Posts By User
Aloesci
Harmless
*




Posts: 28
Registered: 7-4-2018
Member Is Offline

Mood: No Mood

[*] posted on 2-3-2021 at 12:16


Thanks Antigua, Fyndium and mackolol for the information about CaCl2! I have a bunch of it from some dehumidifying products, so I will test around with some different amounts with ice and see just how cold I can get!

I work in a lab for blood transfusions and we use dry ice to keep blood plasma frozen. They might let me take some away.

Also I've read that peppermint oil is about 36% menthol and 24.5% menthone so a reduction could perhaps significantly improve menthol yield? I don't have the chemicals to try but it could be a fun idea.

For now I'm enjoying how minty it smells over here :)
View user's profile View All Posts By User
Fery
International Hazard
*****




Posts: 503
Registered: 27-8-2019
Location: Czechoslovakia
Member Is Offline


[*] posted on 2-3-2021 at 13:25


reduction of ketone to alcohol group using NaBH4 won't be stereoselective... I wonder whether there is a difference between the scent of the 2 stereoisomeric products



If there is a heaven, it seems not to be materially based. Does chemistry exist there and if yes, how does it look like? Are there good souls well supplied with laboratory equipment, glass, chemicals and information?
View user's profile Visit user's homepage View All Posts By User
UC235
International Hazard
*****




Posts: 531
Registered: 28-12-2014
Member Is Offline

Mood: No Mood

[*] posted on 2-3-2021 at 18:30


Menthol is a solid at room temperature. A decent freezer should be about -20C. The yield might be a bit lower but probably not by much. I'm not sure where you're getting -22.2C from. Commercial menthol is typically produced from mentha arvensis oil, which is largely menthol whereas peppermint contains a lot of menthone.

I should add that actual essential oil composition varies wildly depending on weather, plant parts distilled, growth stage, exact cultivar, and soil chemistry.

[Edited on 3-3-2021 by UC235]
View user's profile View All Posts By User
zed
International Hazard
*****




Posts: 2203
Registered: 6-9-2008
Location: Great State of Jefferson, City of Portland
Member Is Offline

Mood: Semi-repentant Sith Lord

[*] posted on 22-3-2021 at 06:28


Ummm. I obtained some material reputed to be Borneol/Isoborneol. So, even though I have a pint of Peppermint Oil in the cupboard, I will be using it for the purpose I originally bought it for. Spraying around my foundation, in an effort to keep ANTS out of my house.

Now, Menthol it turns out, is a top catalyst for producing Sodium by Nurdrage's Method. But, fer repelling insects, I'm thinking Menthone might be the best choice. I was using a semi-natural lotion called "Off" a few years ago. Full of Menthone. When you put this stuff on, bugs leave you alone. Seriously; it really repels them. Deet, can't compete.

So, my quest has sort have been the opposite of yours. How can I convert so-so Menthol, into uber repellant, Menthone? Maybe Perborate?

Oh yeah. Back to Borneol/Isoborneol. A dealer on Ebay is selling it. I'm assuming it's the real stuff. Time will tell. One thing I can say..."It is not Camphor!" Camphor I know. It has kind of a sharp, penetrating odor.

This Borneol, has more of a musty, earthy smell. Not Camphor! https://www.ebay.com/itm/BORNEOL-Isoborneol-Crystals-250-g-F...

[Edited on 22-3-2021 by zed]

[Edited on 22-3-2021 by zed]
View user's profile View All Posts By User
Fery
International Hazard
*****




Posts: 503
Registered: 27-8-2019
Location: Czechoslovakia
Member Is Offline


[*] posted on 22-3-2021 at 13:38


zed you can oxidize menthol using aqueous environment with dichromate+H2SO4, or in acetone environment using CrO3 (Jones reagent) or menthol in ether and oxidizing agent aqueous dichromate + H2SO4
http://www.orgsyn.org/demo.aspx?prep=cv1p0340
https://sci-hub.st/https://doi.org/10.1021/jo00802a005
https://en.wikipedia.org/wiki/Menthone

If you wish I can find you the CrO3/acetone method, we had it as a practical preparatory problem in chemistry olympiad.


[Edited on 22-3-2021 by Fery]




If there is a heaven, it seems not to be materially based. Does chemistry exist there and if yes, how does it look like? Are there good souls well supplied with laboratory equipment, glass, chemicals and information?
View user's profile Visit user's homepage View All Posts By User
Aloesci
Harmless
*




Posts: 28
Registered: 7-4-2018
Member Is Offline

Mood: No Mood

[*] posted on 22-3-2021 at 14:08


If anyone is curious i managed to extract some very crude menthol from some mint, and i made a video about it. I'm a (very) amateur chemist so the video is not really meant for anything documenting my own playing, but feel free to check it out :)

https://www.youtube.com/watch?v=e9UlMjoeukc

I don't think my extraction extracted all the components of the oil so i was left with a waxy solid and i didn't carry out any freezing like i described.
How could i recrystallize my product seeing as it melts between 36–38 °C?
Any help would be appreciated.
View user's profile View All Posts By User
zed
International Hazard
*****




Posts: 2203
Registered: 6-9-2008
Location: Great State of Jefferson, City of Portland
Member Is Offline

Mood: Semi-repentant Sith Lord

[*] posted on 22-3-2021 at 16:26


Menthone to Menthol? Here, I would try to use Aluminum Isopropoxide and Isopropyl Alcohol, as the reducing agents. Seems like it might be the right thing.
View user's profile View All Posts By User

  Go To Top