Chemical Forums
Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: Homeslice on November 28, 2021, 12:06:02 PM
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I am going to try and distill different fatty acids, that boil close to "231 °C at 1.70E+01 mm Hg". So that is the bogie. I have no idea what that 1.70E+.01 mm Hg means, but using google it appears its like .022 atmospheres. That sounds like a big pressure reduction, but I don't know how hard that is to achieve!
Any recommendations for an affordable, decent vacuum distillation set up?
Would something like this kit:
https://www.amazon.com/Distillation-Apparatus-Equipment-Chemistry-Glassware/dp/B07R8JFK97/ref=sr_1_3?keywords=vacuum+distillation+kit&qid=1638117238&sr=8-3 (https://www.amazon.com/Distillation-Apparatus-Equipment-Chemistry-Glassware/dp/B07R8JFK97/ref=sr_1_3?keywords=vacuum+distillation+kit&qid=1638117238&sr=8-3)
And this pump:
https://www.amazon.com/Homesprit-Filtration-Laboratory-Distillation-Apparatus/dp/B083Z98JKH/ref=sr_1_5?keywords=vacuum+distillation+pump&qid=1638056598&sr=8-5
Do the trick?
Any suggestions appreciated!!!
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You need a much better pump and these fatty acids are hard to separate. It will get expensive and maybe not possible at all. You need to look in the literature, these types of compounds are manufactured and purified so there are methods.
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I've never tested how much vacuum it pulls, but I've run vacuum distillations on this $20 pump:
https://www.amazon.com/Karlsson-Robotics-D2028-Vacuum-Pump/dp/B00DYA21PU/ref=sxts_rp_s1_0?cv_ct_cx=vacuum+pump&keywords=vacuum+pump&pd_rd_i=B00DYA21PU&pd_rd_r=e043d3cd-765e-4f40-bb2b-e75992ec4692&pd_rd_w=HAOA3&pd_rd_wg=3xCee&pf_rd_p=29dcfc78-5030-4047-b3bb-fd095cf7aa8a&pf_rd_r=716EZX900NJYH1JDMK7W&psc=1&qid=1638669118&sr=1-1-f0029781-b79b-4b60-9cb0-eeda4dea34d6
There's a good chance that won't be strong enough, but at the price point, it cant hurt to try, and it works great for vacuum filtration so it's not a loss. If it doesn't work, this pump is about the most popular in amateur chemistry. You can find them on sale for about $50 every now and then. Again, never measured the vacuum, but I've seen people get away with doing quite a bit with this type of pump:
https://www.amazon.com/GYZJ-Refrigerant-Recharging-Degassing-Processing/dp/B08B8NSKHV/ref=sr_1_22?keywords=vacuum+pump&qid=1638669166&s=industrial&sr=1-22
With that said, I've never worked with fatty acids outside of instructional labs, so I really cant say if it'll be good enough or not, but I know quite a few other people who use them with success
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The second pump could be good enough, you can see the best vacuum you can obtain in the description of the pump. You also need a vacuum gauge, these are also available but they can be expensive, a pre-used can be an option. On ebay there are lots of pumps and gauges. But still you first need to check in the literature if distillation is the best option.