The Vespiary
The Hive => Newbee Forum => Topic started by: neopharmaphobia on December 10, 2003, 12:50:00 AM
-
If SWIM obtains glycol/epoxide from the Oxone reaction, exactly as posted on Rhodium's site, and proceeds to hydrolize with 15% H2SO4, the result is probably glycol. Freezing the glycol/epoxide immediately after the Oxone reaction (before hydrolisis) would make it almost solid or very thich and slow moving (depending on buffered or non-buffered reaction--glycol or epoxide). However, after the hydrolisis it would still be slow moving. I believe that the hydrolisis failed. Previous attempts of distilling post-hydrolisis product would yield some MDP2P and mostly glycol or epoxide.
What would cause the hydrolisis to fail? Different brands of Oxone were tried, buffered, unbuffered, and varying the ammount of buffer, still problems. Hydrolisis ran at 3 hours. Might the H2SO4 be bad? It is suryupy and has good density (to the best that it can be measured). Is the quality (water content, etc) of H2SO4 very important? All distilled water used. Reflux rate on hydrolisis (with methanol) is 1-1.5 drops per sec. Is the heat too low? Stirring does not stay stable at high speed, but is set to the highest possible (when it stirs and the stirrer is turned off, tiny droplets can be seen forming at the bottom (leading to the belief that the stirring is sufficient to mix all of the reactants). Are there any other variables that may have been overlooked? How viscous is post-hydrolisis ketone when in a freezer? Any suggestions?
-
What temp are you running it at? If its betwwen 70c-80c, then your problem lies within the oxone procedure prior. The hydrolysis step is pretty cut & dry as long as the proper molecule going into it is the correct one. How are you checking your oxone reaction product for reaction completion?
-
Check your sulfuric acid solution(15% that should be) density.Should be around 1.10-1.11 if i remember correctly,check rhodium site for verification.
-
I too have had problems with the Oxone method... I think there's more buffer in the stuff sold in hardware stores than the reaction can use, interferring with the reaction. Never had a yield higher than 15% after distillation. My best (well, most consistent) results have been from the peracetic method (typically around 70% after distillation of the ketone), but I've found there's a window between days 5 and 7 after mixing during which the peracetic acid must be used or yields fall dramatically.
-
Your refluxing your shit at over 70c?? Man do a biphasic with xylene and 10% acid for five hours at 55c and work up. Your going to kill your yields refluxing like that if you go over the needed ammount of time.
-
Trying to get good quality Oxone is tough. I think this is the big problem with this method (well, that and the huge solvent volumes required). The ketone should be quite thin--with a viscosity like the isosafrole. The glycol is however quite thick, like olive oil.
-
What exactly do you mean by good quality? You refering to low concentrations like the 50&85% packets, or improperly stored pacakges of the typical 85% that have begun to break down and lose the properties that make it useful... Acording to my package if it is opened or stored near moisture heat above eighty degrees it gives off gasses and makes h2so4. Or just overall poor quality oxone? I mean it is only going into a swimming pool.
-
I mean Oxone of a known purity, suitable for epoxidation. The Oxone brand I did get my hands on didn't come with an MSDS. I wouldn't be surprised if others encountered the same thing and didn't luck out with good quality persulfate.