Note: This is the first of 3 posts on rotary evaporation. Please note the post date of each article, some older information may be used as reference. Here are links to the following 2 roto instructionals:
As a general disclaimer, I want everyone to know, your recovery and alcohol work is only as good as your equipment. As a general notion, I suggest a caution to newbies. to attempt roto work as if done improperly you will saturate the air with alcohol fumes, and cause a dangerous scenario.
Roto work is time consuming; however, here you will find information that will allow you to excel and complete your task quickly both pre-roto and roto itself.
First off, we need to prepare the liquid source. With solvent reactor systems, it can be very difficult to control saturation levels before the solvent stops working, so here we will discuss closed loop preemptive material handling for roto work. Normally, if you run 4x and make around 450-700 grams total of essential oil extracts, you will fist emulsify this with 200 proof ethyl in 2000ml on a hot plate with stirrer around 80-100f. The lower the better, but we know some components don’t dissolve fully during emulsification. You will then stretch the solution you created say with 500 grams starting material from 2000ml ethyl to 4000ml ethyl. We suggest not to specifically make a cryo loop with your cls. Instead, run cold fluid in one pass at a slightly higher psi with no dry ice in column. This will create mixed phasing in the column creating a nice over all extraction for yields – not colors or appearance.
There are two basic modular setups used in this process.
- Filter apparatus -> cold trap -> variable speed vacuum pump.
- Rotovap -> cold trap -> balloon diaphragm vacuum + controller.
We suggest these components because they work exceptionally, in fact compared to YouTube videos you will never find a better performing glassware set. The Wilmad lab glass 90 mm filter apparatus. At Summit Research we are working on a new ultra high fluid velocity filtration apparatus; however, manufacturing this product is difficult, and cost for custom setups like these are enormous. We are waiting for production costs to come down before we release it, and we need to accomplish numerous monthly side-by-side testing because the Wilmad lab glass filter does work exceptionally to begin with. Our solution is to create a stepped filtration system, as current ones are limited to how much inactives they are catching for efficiency of flow. We want to reduce this effect and allow it to flow full speed no matter what. That will be a future discussion as the current filter we are working on will be in R and D for a while.
The first and very most important step is physically preparing the fluid after you have emulsified it in alcohol. To begin that process, you must understand that not all alcohol is the same, and water is something that you always want to avoid. Components within the alcohol will eventually carry over and create issues during recovery and processing, especially filtering. Kleen extract is not CLEAN ALCOHOL. We do not understand who this company is as they have numerously lied to the public over and over and refuse to release HPLC tests. The concept they ride on is the MSDS. MSDS only contains component by volume % information, and not where the alcohol came from or even the purity. When working with alcohol (say you drink some moonshine), well your body can process the impurities that are within at the same rate as you would get drunk. The body then boils these impurities off in your metabolism; however, after reducing 4 gallons of moonshine, not only would you have nearly a lb or more of the remainder % in either water – but the impurities aren’t in the (example) 30ppm rage but now in roughly 2000ppm (16 cups per gallon x 4 gallons, 1 cup starting rage at 30ppm). Another thing to consider is that with cheap alcohol like Kleen extract there is ZERO heavy metal removal prior to packaging. Alcohol is famous for coming out of cheap laps using rotten grain and bacteria sugars that cannot be sold. Often they use steel, iron, copper etc to make alcohols. Some companies will re-boil off the alcohol in a stainless reactor or even glass reactors, but the source contamination is still present and cannot be just 30ppm but instead 3000ppm overall, easily. Imagine recovering 4 gallons of alcohol and the ppm left behind. We have read and observed weaker winterizing effects with grape alcohol and other forms of novelty alcohol. The reason being is the purity is not matched by 200 proof ethyl. Also – a handful of alcohols in your backpack may equally get you drunk but clearly have different molecular bonds and avail chemical characteristics. The only lab grade HPLC alcohol you are to ever use with this process, if you care about the quality of your process and stand behind the end result of your products, is 200% ethyl with lab test. The price of this alcohol is roughly $140 per gallon in a case price. Right – it’s cheaper than those knock off brands. You would never ever see a lab use grape alcohol or Kleen extract in their hardware uses, so why would you use that? Oh yea, your FAM told you too…”hey bro I heard this cheap shit everyone is using, you should try it – oh yea thanks FAM”.
Other points to consider are hardware, health, and recover-ability, with alcohols not suitable. If you use 200 proof ethyl right off the bat, your recovery rate will be say 100% speed. If you use a 190 proof with 5% water in it, your recovery rate will be roughly 75% of that speed depending on solution saturation. If solution is heavy, then your recovery rate will also be even slower. Everclear is also not suitable because it has alkaline flavors that are carried over during distillation, which will create a bitter metallic flavor that is left behind. We have heard numerous complaints of this with drinking alcohol but some people have not had these issues. So if there is nothing left to use, try everclear. At least we know everclear is probably cleaner than KLEEN EXTRACT. Kleen extract is not good because nobody knows what is in it or how it will concentrate, and the owners refuse to release any info. Transparency is the most important thing we can achieve in the industry around us. We want to stride for the best and have the work to reflect that. Watching artists and cholos post Instagram using the most rudimentary and shittiest closed loop setups and hardware is a joke. No scientist would take them seriously. In fact why do you take them seriously? Probably because many people are on a branding game with FAM, and they are not really looking past the smoke screen of media. All of which is in a effort to falsely emphasize skills that one does not possess in a method to gain business and profiteering schemes to fill their pockets. If you are good, then you don’t need to advertise. People will come to you. If you are going to advertise make sure it’s done with the best gear money can buy. Don’t maverick your way through life buying the most bottom dollar hardware and then still not know how to use it. Learn, buy, excel, advance, and become all that your skills can be.
When we talk about alcohol quality the very best is a corn/grain ethyl lab grade, not fruit derived, not mixed. Just a raw pure 200 proof ethyl that has been both, micron filtered biologically and tested by hplc to ensure quality and reactivity. Water present will actually damage the hardware, ruin the recovery(h20 attaches to ethyl vapor), extend the process, and leave behind things you just don’t want. Water will also prevent the ethyl from staying viscous under low temps. Even the slightest water present will prevent ethyl from filtering fast. Some issues people noticed with Kleen and ever clear is fogginess. We believe this is mineral based, which causes your final product to look foggy. Some companies use limonine and other components to flavor their poorly processed extract. They Think the cloudiness or poor flavors are attributed to the source material. No, it’s the source supplies and hardware. Before making any assumptions or alterations to a process, you must first start with the correct chemicals, hardware, and skills. Then you may learn how to identify the issues and backtrack problems to create solutions. Otherwise, if you are using crap to begin with, your just like an artists who is guessing on a process without truly really knowing. This is very important because I have seen numerous people attempt and try and fail over and over because they decided to use cheap shit and make changes that were relevant to the process and never succeed. Once I rearranged their thought process and emphasized to go buy correct alcohol or filtering mediums they instantly had night and day results. You would be surprised how the smallest details carry over into the greatest results.
As we stated first step was emulsification of your product.
***this step is optional, place your product in separatory funnels for initial mechanical separations and or centrifuge to mechanically separate by density the inactives. You can collect these later and create a separate filtered grade of fluid to work with***
The next step is to take your emulsified solutions and to make sure the viscosity is correct and cryo them. Around -15 to 0f seems to be the right spot. Then, using a modular filter apparatus, lay 5u filter paper grade 412 on the glass frit. Assemble the funnel onto the filter, and lay expanded glass wool down. We feel, depending on saturation levels, 500-1000ml of fluid can be filtered at a time. With a seriously wax and impure batch of solution you should see roughly 1min per 1000ml of fluid, if the filtration is prepared correctly and the fluids are prepared correctly. This physical filtration is on top of any mechanical filtration you may be doing. Even warm wax filtration’s can work. The whole concept is no matter how fucked up your fluid is, you can separate the head fluid and tail fluids into grades. In this case we want to strip out obvious crap from the fluid prior to cryo filtering. This will allow the fluid not to bind to the impurities and the time it takes you to filter will determine how well you filter. If you are waiting for a shitty Buchner funnel to operate and numerous passes still flowing slow, then you need to reevaluate your hardware and process. The faster you can filter (not speed of paper) the better the fluid will be because it is not sitting on the surface clogging itself up while the fluid re-dissolves shit back down. The use of glass wool is the most important factor. Remember preload your filtration. As I said earlier with the filter bases, filters are made to be used a certain way. If you cannot do that, you need to quit fucking around and get a day job. Everything has a use, and everything should be used properly, like using a channel lock to pull a bolt off when you have sockets and box wrenches. The glass wool will immediately freeze and gravitate contents to the material itself while the fluid thins and becomes free flowing under the glass wool. Your filters again will look nearly clean and like new. Extending the life and speeding them up considerably. Like I said, we have ran 1000ml of fluid with roughly 150-200 grams of essential oil contaminated product through a filter in about 1 min. It can be done. Anyone struggling with filtration speeds is using the wrong filtration hardware and processes and or misusing what they have.
The next process to understanding alcohol filtration is the inherent ability for the alcohol to vaporize and contaminate your pump. When we see maverick trying to use a hvac vacuum pump on everything it is a sign not to try that at home. Alcohol vapors will condense and fill your pump up with alcohol in minutes of use, completely removing the stator vapor head space for proper vacuum ratings and achieving speeds that now will fluctuate. Also alcohol in the oils will enable de-laminating of the stator, which will ruin your vacuum pump in about a week, even with fluid changes. We just ruined a brand new e2m30 in about 10 uses approx. Most people think to just reload oil and go. Yea it may work, but what will you do the moment that vacuum pump fails and the stator will break in half cracking the case and sending nasty fractioning/recovery alcohol and fluids all over the room? Yea exactly, like we said, everything is designed to be used a certain way and there is always the right tool for the job.
We have found one of two ways: digital vacuum control with a start-stop action control on the pump helps on to reach a relative vacuum rate with pausing for hysteresis and then restarting. This is the most common and highly utilized method for rotovap; however, it isn’t as efficient when doing filtration. The solution is a variable hz controller on the vacuum pump used. You can use a standard oil vein(we use e2m30) and we can literally slow down the rotation of the motor, which enables complete control over the amount of vapor available in the hose path vs. the vacuum pressure. This is done with a glass cold trap. As you initiate vacuum, the filtration setup will begin vacuum, and the vapor coming from the head space of the filtration flask will get carried over to the your cold trap. If used correctly you will see a fog filling up in the cold trap. The rate of freq/hz on the pump, at this moment, will allow the fog to either pass up the condenser or related to 2/3 effect of the condenser. 2/3 to 3/4 is about where you want that fog to stop at. If you see it past the exit port you are vacuuming too fast. This will load up your vacuum pump relatively fast and well…. you’re just shitting money at this point. Alcohol is expensive and should be handled like gold. This way you will recover scent free, color free, 99.9%+ style recovered alcohols. The idea behind what we are teaching you is that you get the alcohol back at nearly original proof. Why not save and return it at as close to 200 proof.
When we start teaching people about roto use, one of the things we are battling against is incorrect hardware. No you do not need a 12-30k rotovap. Believe it or not the heidolph salesmen nearly doubled their money when selling that brand. We won’t mention names because it is a profit margin game. When we bought our first rotovap we chose a Buchi r-100+v700+i100. This combination is simple, cheap and effective. And the new r100 systems are nearly silent and don’t need any excess hardware. You aren’t going to be making gasoline or any volatile fuels. You are just dropping your evap flask into the bath and adjusting vacuum, the speed only needs to be adjusted near the end to excite the reaction. Most digital units only have a digital control for speed and height. However without buying a proprietary preloaded software, like the v800 type controllers, those electronic elevated units won’t even be needed. Your height won’t change once your flask is in the bath. Mechanical lift rotos are almost nearly useless, as they are used for tailing the condensation rate. Normally, when making volatile fuels, the roto cuts heat short and lifts itself up chilling and cooling the product inside, which creates a safe way to open the flask. We are using alcohol. I can assure you, this feature, even if programmed correctly is NOT needed at all. We suggest using a pear-shaped evap flask as this will help the speed and efficiency of the process. The round bottom standard neck-style actually does not rotate the insides as smoothly. It tends to create a roll over turbulent effect vs. a pear-shaped flask, which will create a swirling less turbulent effect. We don’t want to bump the over excited chemicals, we want to create a fast thin film movement on the glass. This will help the speed be as smooth as possible, which will create a slight bubbling effect. This is the maximum proportional effect we want when recovering alcohol.
When you being to run your rotovap we suggest starting at 150mbar, then step to 100mbar. Within this time, the flask temps will increase and begin sending vapor up. The first thing will be remainder noble gasses that destabilize and pop off first. Do not fret – you are not supposed to collect those. They are not needed. It will look like the solution is partially carbonated but it is not. After this effect, the solution will become relatively non-reactive. At this point, your condenser will slowly start to piss, very slowly. Maybe a drop or two. At this point, drop mbar to 75 and allow that to sit until 4/5ths of the fluid is evaporated. The speed can be increased with added speed on the flask. We note around 40c is the best spot for alcohol recovery on the bath. If you drop mbar too fast the alcohol will destabilize under vacuum sending way too much vapor up the neck. Your vacuum pump will seem like it’s going faster and struggling as the vacuum gradually decreases and mbar will reach about 140 approx. Here it will teeter while the vacuum pump is over pulling. This will damage your vacuum sensor as literally solid vapor condensate will leech into your lines and such. The lowest you’ll need to go to create a gel from your starting solution is roughly 40-50mbar at max. If your vacuum pressure is bumped too fast or too hard, you may suffer from decreased vacuum. Shut off the vacuum pump for 30 seconds and put it back to 125 mbar, and slowly take it back down until the vacuum depth is stabilized so the pump may operate in hysteresis. When running say 75mbar your vacuum pump should hit this rating. Stop. Wait about 5 seconds for hysteresis to gain 10 pts, say from 75-85mbar max, and then it will turn back on. This on- and-off process is not suitable for oil vein. It is only suitable for dual diaphragm balloon vacuum pumps similar to the Buchi v700 or type.
Always keep the joints clean, and dry. When you are finished, those clean and dry joints will not gum up and weld tight, so you will easily be able to remove them. When using the roto it is preferred to use a media bottle to collect your finished product, do not keep adding product to the evap flask as it will slow down your recovery considerably. Sometimes 3/4 of the speed slower. You can load a 4l flask half way and run it 10x over and over, and still complete in more than half the time that you would be re-adding solution to your roto. The molecular bonds and saturation are too great at that point to produce fast vapor release. This is for lazy/stupid people who do not understand how to work a machine. Wait did I say lazy? Yes we are the laziest mother fuckers you will ever meet, and we still would rather run numerous batches over and over and collect them all last. You can re-run the last collected batch as well if you need to get to a denser gel. We have ran one flask and added another with no issues but this was total of 3000-4000ml fluid max (2 runs collected). Anything outside of this would be difficult and extremely time consuming. Remember time is money
If you need any clarification or help or want anything added to this how to and pro use tips please email tech@summit-research.tech/ -JBV