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

Printable Version  
 Pages:  1    3
Author: Subject: PETN vs. RDX
Microtek
National Hazard
****




Posts: 492
Registered: 23-9-2002
Member Is Offline

Mood: No Mood

[*] posted on 29-12-2006 at 01:50


@ Nitrojet:

When you do the transesterification of castor oil to obtain methyl- or ethyl ricinoleate, which set of reaction conditions do you follow ? In that pdf they used both high and low temps, both KOH and NaOMe as catalysts, etc.
When I attempted the reaction, I mixed castor oil and ethanol ( 100 % excess ) with ca. 1 % KOH dissolved.
I then capped the flask and shook it vigorously. It quickly became homogenous ( I had thought this would take quite a while ) so I added a magnetic stir bar and stirred it for 2 hours at room temp.
I then let it sit overnight, but no phase separation occured. If I add some of it to an equal amount of water, slight agitation causes an emulsion to form, which isn't the case with fresh castor oil so this is promising, I suppose. However, the product doesn't seem to be very soluble in gasoline.

Does this correspond to your experiences on the subject ?
View user's profile View All Posts By User
quicksilver
International Hazard
*****




Posts: 1820
Registered: 7-9-2005
Location: Inches from the keyboard....
Member Is Offline

Mood: ~-=SWINGS=-~

[*] posted on 29-12-2006 at 06:35


I am pretty sure needle size / shape could be controled with temp and other specifics within the recrystalization process. And I'm also willing to bet that the actual moxing results in shaving of the material more than would be expected. but a source for industrial / pure PIB...that, I have not found. (If anyone knows, please U2U me, or post). - IF the process of re-crystalization is done in reverse using a single ice cude as a seed the length of the needle becomes much shorter and thicker, making them "fit together" in a denser format.



View user's profile View All Posts By User
nitro-genes
International Hazard
*****




Posts: 971
Registered: 5-4-2005
Member Is Offline

Mood: No Mood

[*] posted on 30-12-2006 at 14:18


I took 100 ml of methanol and 100 ml castor oil. A very large excess of methanol was used since this makes dissolving the NaOH/KOH easier and prevents this gelatin mass you describe. Then I warmed the methanol slightly to dissolve all of the catalyst, this is easier with KOH than with NaOH btw since the first is more soluble in alcohols than the latter. All of the catalyst, KOH or NaOH, should have dissolved in the alcohol before you add the castor oil! When using ethanol be sure though that it is as waterfree as it can possibly be, since using a large excess of water-containing-ethanol will result in a very bad yield or even no product at all...

After adding the castor oil, warm to near boiling point of the alcohol to reduce the reaction time to about 3 hours IIRC. (could have been 4 hours :)) Unfortunately, phase separation will not occur. According to the article this is mostly determined by the catalyst used. IIRC, using sodium ethoxide does result in phase separation, whereas KOH or NaOH (like I used too) does not...

Not that it really matters, the oil is the only reactant that would be difficult to seperate from the isopropyl rincinoleate, but the conversion of the oil should be near 100% (when using absolute alcohol). The rest of the products, like potassium oleates, glycerine and the excess ethanol can all be removed by washing with water. The end product should be a very runny oil, slightly more viscous than water and completely non-volatile...
View user's profile View All Posts By User
nitro-genes
International Hazard
*****




Posts: 971
Registered: 5-4-2005
Member Is Offline

Mood: No Mood

[*] posted on 30-12-2006 at 14:19


I took 100 ml of methanol and 100 ml castor oil. A very large excess of methanol was used since this makes dissolving the NaOH/KOH easier and prevents this gelatin mass you describe. Then I warmed the methanol slightly to dissolve all of the catalyst, this is easier with KOH than with NaOH btw since the first is more soluble in alcohols than the latter. All of the catalyst, KOH or NaOH, should have dissolved in the alcohol before you add the castor oil! When using ethanol be sure though that it is as waterfree as it can possibly be, since using a large excess of water-containing-ethanol will result in a very bad yield or even no product at all...

After adding the castor oil, warm to near boiling point of the alcohol to reduce the reaction time to about 3 hours IIRC. (could have been 4 hours :)) Unfortunately, phase separation will not occur. According to the article this is mostly determined by the catalyst used. IIRC, using sodium ethoxide does result in phase separation, whereas KOH or NaOH (like I used too) does not...

Not that it really matters, the oil is the only reactant that would be difficult to seperate from the isopropyl rincinoleate, but the conversion of the oil should be near 100% (when using absolute alcohol). The rest of the products, like potassium oleates, glycerine and the excess ethanol can all be removed by washing with water. The end product should be a very runny oil, slightly more viscous than water and completely non-volatile...
View user's profile View All Posts By User
 Pages:  1    3

  Go To Top