Hexane Honey Oil

Ever thought of using N-Hexane for extraction or alchemy? At the skunk pharm we use an HPLC reagent grade hexane, which we acquire from the local scientific supply store, for a number of things.

Like butane, hexane is a simple alkane, but it has two more carbon atoms and four more hydrogen’s, which makes it completely insoluble in water. Pentane, with five carbons in the chain, is the first completely insoluble alkane.

It’s longer chain gives it a higher specific gravity and higher boiling point than butane. Hexane boils at 69C/156.2F, versus -0.6C/30.9F for butane, which makes it more difficult to purge.

It can be purged under heat and vacuum using thin film techniques, or simply washed in ethanol, which boils at 78C/172.4F.

Our sensory perception threshold for hexane is 30ppm and OSHA TWA limits for breathing it 8 hours, is 500 ppm, so we can detect its gasoline like taste far below TLV.

Hexane is commonly used to produce pharmaceuticals and even food products, and is not Mother’s Milk, but the point is moot, as it is not left in amounts that are toxic.

There is a difference between trace amounts and toxic doses, because poison is in the dosage. Even Oxygen is a toxin at over 75% atmosphere and you are just as dead as from an over dose of any substance.

So what are the facts about hexane? One is that if hexane is present at levels as low as 30ppm, it tastes exactly like gasoline.

Since concern starts at 250 ppm for chronic and nearly continuous exposure, our senses are adequate to protect us from exposure to toxic levels.

So lets see what the governing authorities think about it, while paying attention to how the dosage rates compare to levels less than 30 parts per millionth:

SECTION 11 – TOXICOLOGICAL INFORMATION

CAS# 110-54-3: MN9275000
LD50/LC50:
CAS# 110-54-3:

Draize test, rabbit, eye: 10 mg Mild;
Inhalation, mouse: LC50 = 150000 mg/m3/2H;
Inhalation, rat: LC50 = 48000 ppm/4H;
Inhalation, rat: LC50 = 627000 mg/m3/3M;
Oral, rat: LD50 = 25 gm/kg;

Carcinogenicity:

CAS# 110-54-3: Not listed by ACGIH, IARC, NTP, or CA Prop 65.

Epidemiology: Occupational polyneuropathy has resulted from hexane exposures as low as 500 ppm, but the minimum levels of n-hexane that are neurotoxic in humans haven’t been established.

Nearly continuous exposure of animals at 250 ppm has caused neurotoxic effects.

Teratogenicity: No evidence of teratogenicity or embryotoxicity in anmial studies with hexane.

Fetotoxicity has been observed in the presence of maternal toxicity.

Reproductive Effects: Severe testicular damage has been observed in rats exposed to hexane at concentrations which have produced other significant toxicity.

Although sub-neuro toxic doses of its principle toxic metabolite, 2,5-hexanedione, can induce progressive testicular toxicity in rats, there have been no reports of human sterility or other reproductive toxicity associated with n-hexane exposures.

Mutagenicity: Positive results (chromosomal damage in the bone marrow cells) obtained for rats exposed by inhalation to n-hexane.

Neurotoxicity: n-Hexane is a mild irritant and CNS depressant in acute exposure, but its principal effects are damage to the sensory and motor peripheral nerves, particularly in chronic exposure.

Moving to ease of use, because of its insolubility in water, you can soak plant material in hexane without picking up water solubles.  I have soaked as long as 12 hours.

Using hexane requires close attention to safety issues, as it is highly flammable and even lower explosive limits than butane when used in an unventilated area.

Hexane’s lower explosive limits is 1.2% of atmosphere, and its upper explosive limits are 7.7, as compared to lower limits of 3.3% for ethanol and 1.8% for butane. Except for well ventilated lab conditions, hexane extraction and alchemy is best done outdoors, with a fan blowing away and dispersing the vapors as they are given off.

Pentane and Hexane are the components of light naphtha, or white gasoline, and should be treated with the same care and respect.

Needless to say that it a no smoking or toking activity, so leave the lighter and smokes out of reach, lest you reach for them automatically.

Besides open flame, static sparks can ignite the fumes, so don’t do hexane extractions wearing plastic clothes, especially on cold dry days.

Using glass wear to contain highly flammable liquids carries drop and splash dangers, which I am going to draw your attention to, but confess that I routinely use lab glass wear with flammables in it and that the hexane itself usually comes in a glass jug.

A stainless steel container for the soak portion of the process, could achieve the same effects however, without the same breakage danger.

Ambient temperature is important, and hexane has a relatively high vapor pressure of 151mm Hg @ 25C/77F, so it is important to keep the mixture relatively cool for long soaks or use a vented container to control pressure buildup.

We use hexane for both extraction and cannabis alchemy. Because it is relatively expensive, it is usually more cost effective to do the initial extraction with another less expensive solvent and use a lesser volume of hexane to polish it afterwards.

For extraction we simply fill a jar about 2/3rd full of material that we have broken up to about coarse rolling size, and fill the jar to the 3/4 level with hexane. We shake well, loosen the lid to release the pressure, seal it again, and set aside.   We periodically repeat the shake and pressure relief steps, for up to 12 hours.

At the end of the soak, we pour the mixture in a strainer, and press the material to force as much hexane out of the plant material as possible. We then filter through a coffee filter or vacuum filter using a Wattman # 1.

You can do the initial purge of the hexane by simply setting it aside in a pie plate to evaporate, and can speed that up by setting the pie plate in hot water and blowing air over it, if you aren’t in a dusty setting.

You can also boil off the hexane in a double boiler, with either hot water or hot oil as the medium in the pot, and can speed that up with vacuum. See attached pictures of thin film vacuum purging, as well as a ghetto rig in a fruit jar:

That brings us back to final purge, and as I noted above, if you don’t have vacuum equipment, final purging can also be done by washing in ethanol. Washing is done by re-dissolving the raw HHO in ethanol and boiling the ethanol off. The higher boiling point of the ethanol and the scrubbing action of the alcohol molecules boiling off, will take the remaining hexane molecules with it, while keeping the process temperature below 173F.

Re-dissolving in ethanol also allows the interim step of winterizing, by which you place the ethanol HHO mixture in the freezer for a couple of days until the waxes coagulate and can be filtered out, before evaporating away the alcohol.

While it can be used for extractions, where hexane really shines, is cannabis alchemy. For instance, you can extract the cannabinoids with ISO, Methanol, or Denatured alcohol and after reducing the volume of the alcohol through evaporation, when it reaches a convenient and economical handling volume, mix it with equal parts of hexane and super saturated salt water.

If you agitate that and place it in a separatory funnel to separate, the hexane will rise to the top with the cannabinoids and the water and alcohol mixture will sink to the bottom, where they can be bled off. See picture of separatory funnel, and check out our page on polishing extracts for more details.

Lastly, we use hexane to isomerize or make cannabis acetate. That involves reflux boiling the hexane cannabis oil mixture in sulfuric acid, or acetic anhydride.

More on that in Joe’s Cannabis Acetate thread.

197 responses to this post.

  1. Posted by Nick on August 19, 2016 at 10:32 AM

    Can anyone tell me why hexan is even required in all this? What would be the problem with extraction via isopropyl throw the aliquots a into a rotovap to evaporate off 80-90% of the ISO to a point where it’s still workable then transfer to the fractional distillation apparatus to distill the rest of the ISO off and then do you fractions at slowing increased temps? All the lipids and chlorophyll should just stay in the round bottom and won’t boil off until the last fraction, right? The end use of the product would be for vaping not edibles if that even matters.

    Reply

    • Posted by redturtle984 on August 19, 2016 at 2:33 PM

      In this process it is a required component because the title of the article is about it.

      Reply

      • Posted by Nick on August 19, 2016 at 7:18 PM

        Haha yeah I noticed that after I posted. sorry about that. Not really the right article to be asking. You seem really knowledgable on the subject. is there anyway to contact you directly to ask your opinion on a few things?
        -nick
        campbeln2007@hotmail.com

        Reply

        • Posted by redturtle984 on August 20, 2016 at 3:01 AM

          lolz, I was half joking in the response hehe. My contact is my screen name redturtle984 at gmail dot com. Drop me a line anytime.

          Reply

  2. Posted by redturtle984 on August 7, 2016 at 9:01 PM

    Azeotrope is easy to look up on the internet, but if true what this person is suggesting is that a ternary azeotrope exists between these substances then is simple to check; if these three do form an azeotrope then distilling them under standard atmosphere will not seperate them. They will come out of the condenser in the same ratios that they boil at, complicating seperation.

    Isopropyl Alcohol and water form an azeotrope known as rubbing alcohol. If you distill water and isopropyl alcohol then you get both back at the same ratio they were before because they form an azeotrop (constant boiling temp) rather than a non-azeotropic mix in which each component boils off at seperate temps.

    If the assertion that these three form such a combination is true then in order to use fractional distillation it must be carried out at reduced atmosphere. These are other ways to “break” an azeotrope too. For instance, if you want isopropyl alcohol in a form mostly free of water, you can add salt to the mix. The salt breaks the azeotrope formed between iso and water and the two will seperate into seperate immiscible layers. Try it. Very cool to watch happen. Alcohol goes to top by itself, and salt water settles to bottom. It is a simple way to cheaply obtain relatively pure iso from any grade of rubbing alcohol – just salt out the water.

    Reply

  3. Posted by Rich on August 7, 2016 at 3:59 PM

    I am used to making RSO w 99.8+ isopropyl. Soak time is suggested at only 3 minutes so other non THC compounds dont go into solution, such as waxes, chlorophyll etc.
    So I’m surprised the soak time for hexane is 12 hours. Thoughts?

    Reply

    • Posted by redturtle984 on August 7, 2016 at 9:58 PM

      I routinely disolve supercritical fluid extracts in isopropyl alcohol as the first step in refining them. At room temperature, unless agitated, the extracts left to soak in iso can still not be dissolved completely in more than an hour. Depending on the xtract it sometimes involves several minutes of vigorous shaking to disolve every last bit.

      Since the extracts are orders of magnitude easier to disolve because they have already been seperated, I am having amtough time visualizing how just a few minutes soak of plant material can extract the same things out of the plant in such a short time? I have speculated that one thing that makes RSO effective is likely trace residue of iso which in theory is an anesthetic in mammals. Since RSO clearly spells relief for so many I often wonder if there is a synergy between trace amounts of it and other plant constituents. I am absolutely certain that extract refined with iso is far and away better than other processes I use. Generally makes the oil turn red if it is cooked low and slow leading up to a boil. Yum.

      Reply

  4. Posted by R&D the cure on August 7, 2016 at 3:44 PM

    That means you need to use a column when you reclaim the solution. If two different compounds boil together than there needs to be a column to cause the ethanol and water to reconsid and not come out in the distallation process. Thanks for that info, I was wondering what was happening.

    Reply

  5. Posted by Nicodemus on July 30, 2016 at 4:42 PM

    It’s worthy to note that if you are intending to reclaim your hexanes, that they form an azeotrope with ethanol and H2O.

    Reply

  6. I have as a and eye problems can this help me.

    Reply

  7. Posted by redturtle984 on June 17, 2016 at 3:11 AM

    I have learned how to tease out the red color, purify, and control the general makeup of dispensary extract in preparation of running a cryogenic sublimator to attempt to photograph amber and red crystal formations of Delta 9 THC. I use isopropyl alcohol in the process which is fully removed. Isopropyl alcohol can be fatal in doses as little as eight ounces. My whole process prior to evaporation uses a tiny fraction of that dosage and is therefor safe even if exposed.

    I vape everything I make. The Cherry Red oil is by far the smoothest, fruitiest, and most pleasant body rush and mental focus medicine I have to date used – and I use a LOT. The reality of purifying the med this way is from dispensary to vape the process removes 25% nominal material by weight. Most of what is removed smells and looks just plain gross, but there is some transfer loss which can add up. It makes gleening fun though lolz.

    Reply

  8. Posted by Ryan on May 27, 2016 at 7:26 AM

    Where can I find affordable hexane? I’m not-for-profit, so can only afford iso by the gallon. N hexane is exponentially more expensive but I want to try it. Also, than you for the great info!

    Reply

  9. Posted by Tim on January 26, 2016 at 8:11 PM

    Hi graywolf,

    The first thing I would like to say is thanks for all the amazing information. I really, really appreciate it. I wanted to ask you about hexane extractions. I have a question I was hoping you could answer.

    It seems like hexane oil extractions can still be very dark after filtering through coffee filters and “removing” the chlorophyll. My thought is that some of the chlorophyll is still present but it doesn’t exactly make sense since as far as I can tell hexane won’t dissolve water.

    The samples were dissolved in isopropyl, evaporated then redissolved in hexane. Then it was filtered through coffee filters and some thin wire mesh, removing a large amount of thick green material. After it was dissolved in hexane it was mixed with water and stirred under heat for a while. Then frozen to remove the water and evaporated down. It however still remains quite dark.

    A few notes,
    Salt was not added to the water

    I would appreciate if you have any knowledge of why its still so dark, and any methods that might be available to change that.

    Reply

    • in your initial rinse, how long are you letting the material “soak”? Are you doing sub zero rinses? or room temp? In my experience keeping it cold along with precise timing keeps the color for me. I have never experienced any green in my rinses mostly cherry and gold.

      One thing you might consider is cutting back your soak times. start by cutting them in half and work up hour by hour. this might just help your color problem.

      Reply

      • Also, as you are doing the fill, shake and drain process, make sure that you have enough hex in the mix to keep the oil dissolved good. I found that after filling and draining over and over the hex would gradually evaporate and I would have to add some new (~50ml) to the separatory funnel a time or two to keep the process going in the right direction. (the process—> right direction = removing the dark color) REMEMBER! Always use care when handling/opening a container of n-Hexane. The very high vapor pressure of this stuff is a trip and all the agitation increases this property!

        Reply

        • fantastic advice. good point man, kudos! I affectionately call that “sprinkling”. Hex DOES evap. very fast and you most definite can F*&^ yourself during this process if you are not mindful of time vs evap. when it comes to hex.

          Reply

        • Posted by Timothy on February 1, 2016 at 8:21 PM

          Hi,

          Thanks for the replies guys. Just to be clear I’m hearing that you redissolve the samples in hexane and filter several times. This seems like a prudent idea as any chlorophyll should stay behind in the filtering layers. My question is in large samples around 1/4″ thick (6mm) is it always going to look black or should it be transparent.

          How many times do you repeat the fill shake and drain process?

          I’d also really like to know the specific compounds that hexane might pick up that isn’t a active ingredient or a terpene. I was looking into beta carotene but as far as I can tell only a small amount should exist since pubchem lists only 109mg dissolving in 100ml of hexane.

          https://pubchem.ncbi.nlm.nih.gov/compound/5280489#section=Melting-Point

          I’ve really not much chemistry knowledge but I thought chlorophyll shouldn’t dissolve in hexane as well, which again perplexes me why the color remains dark.

          It may just be sample size.

          In response to Shivago Joe, the rinses are about -10C from like 5 minutes to as long as 12 hours and they don’t exactly look green, the edges look gold but looking directly at the sample all I can gleam is black.

          Oh and I most definitely agree hexane does evaporate very fast, I would never get near it without a gas mask.

          As a side note it seems condensing hexane vapors is more than a small challenge due to the unusually high vapor pressure at normal operating temperatures. One possible solution is heating a closed system, but well ….. I don’t know if I’ll be willing to try that without quite a bit of research first.

          Reply

  10. This shit is analogous to cooking meth. Yall aren’t even getting high from weed at this point. You know every additional chemical added leaves residues that DO NOT vacuum off….

    Reply

  11. He’s solely 23 years previous and he might easily win this week
    it is just do you want to take 16 to 1 odds on him?

    Reply

  12. Hello I am wondering if all the extra “rinse” steps are totally needed? I have been using more or less the same procedure but when it comes to evaporating off the white gas, I use minimal heat at forced air(controlled). The art form, for me, is in the last evap. making sure that I don’t heat it up to the point where it will burn because we all know how fussy thc can be in this form. Also are the super long rinses a better way to go? I have been doing about up to 2 hours max. and getting two good batches and one “lesser” batch from that initial rinse procedure. Is doing a cleanser rinse with ethanol a vital procedure? I have not been using anything to rinse away the final traces of white gas I have just been purging with minimal heat and “kneeding” the oil with a 2″ wide spatula. I hope I have not been slowly killing myself all these years hehe.

    Reply

  13. Posted by Onlysurvivor on September 26, 2015 at 7:09 PM

    GW, Thanks for all the REALLY helpful information, you guys must have a great time doing what you do! I was going to use the term “blast” but thought otherwise. My question(s) have to do with cold boiling, purging and recovering as much of the solvents used (Hexane and Ethanol) at room temperature as described below and if this process will work. You have much more experience so we look to the “Master” for his opinion.
    A friend sent me his “recipe” for HHO. It seems very straightforward and clear process.
    This process seems slightly safer than boiling under heat since it is performed at “room temperature”, I guess the area is hot since the stated temp is 21c or 80f.
    If there are any missed steps or critical errors PLEASE ADVISE. Would you please review it as I would like to try it ASAP.
    Here is the process as explained to me:

    Materials List:
    112g of high grade dry (40% humidity) bud
    1 Liter of HPLC Grade Hexane 98%+
    1 liter of 95% Ethyl Alcohol
    1cf Vacuum Oven or vacuum chamber (since heat is not required)
    1000ml vacuum distillation kit and stand to hold it.
    70mm Ceramic Buchner vacuum filter kit and slow 70mm filter paper
    Vacuum pump, Vacuum gauge(s),
    Submersible fountain pump (small), air tubing, 5 Gal bucket
    20Lb Ice
    2 big mason jars with lids
    gloves, goggles, lab coat, assorted glassware
    Lots of Isopropyl Alcohol and paper towels to clean up
    A work Area with plenty of ventilation (OUTSIDE), no source of ignition or flame

    1. Grind the material to the consistency of course coffee grounds, remove any sticks and twigs.
    2. Soak Material covered in Hexane for 12 hrs in a Stainless or glass container semi-sealed and allowed to release the pressure. I put it in the fridge to minimize evaporation. Mason Jars work fine just don’t tighten the top.
    3. Vacuum filter the soaked material through “Slow” filter paper (you can cover the top of the filter funnel with clear plastic food wrap and a rubber band which will increase the vacuum pressure as the plastic food wrap is pulled down adding pressure to the material getting more of the liquid out), save liquid. If any solid material is present in the liquid repeat step 3 until there is no vegetable material present.
    4. Take the filtered bud material and repeat steps 1 & 2 again, 2 runs should be sufficient if you have enough Hexane left or use the recovered Hexane. If you repeat the process and distill each hexane extraction individually you will see that the first extraction gets about 98% and the second gets very little but one pass doesn’t get it all and we would hate to throw away any of the good stuff.
    5. WINTERIZATION; Mix filtered Hexane with equal amount of 95% Ethyl Alcohol and Place the filtered liquid in Freezer for 12 hrs and allow the waxes to congeal. You can place it in the freezer in a bath or bag of dry ice to reduce the temperature as much as possible (**do not place dry ice in the liquid) Time and temperature are key so, as cold as you can get it works best (-50) but most freezers give up long before that. It takes time for the waxes to congeal enough to filter them out, that’s why the 12 hours.
    6. Vacuum filter the liquid again through slow filter paper ** We Freeze our ceramic Buchner filter prior to vacuum filtering the waxes, as they will melt back into the liquid so keep the funnel as cold as possible during this step. Keeping it really cold is really good in this process so colder the better. Allow the waxes after filtration to air dry and they can be used in hand cream or other uses
    7. BASIC FRACTAL DISTALLATION: Place the now filtered liquid into a distilling flask of sufficient size and connect to the distilling column with the thermometer in the liquid, it will take a while for it to come up to room temperature (21c 80f).
    8. Once the mixture reaches room temperature, Vacuum distill the Hexane off at room temperature (21c) at 22 In. Merc. On my Gauge, either by maintaining the vacuum pressure or the temperature the Hexane should distill off long before the alcohol, if you keep this a constant. This can take awhile depending on the volume. **Measure the distilled Hexane to make sure you got MOST of it. ** I have a 1000ml vacuum distillation kit I bought on Ebay with 2X 1000ml boiling flasks, 1x 300mm Liebert condenser, a few fittings, to which I added a 300mm Graham condenser in series to the Leibert condenser being first in line. I feed chilled water from the bottom to the top of the columns using a small submersible fountain pump in 5 gallon bucket filled with ice and water that recirculates. Place a collection flask just past your vacuum port in an ice bath and turn on the pump to controlled vacuum pressure. Save the re-distilled Hexane to use on the next batch.
    9. Once you recover the majority of the Hexane, change to a clean flask and raise the vacuum to pressure 28 In. Merc. And the alcohol should start distillation, this will also remove any lingering Hexane. Recover as much of the alcohol until the oil mixture starts to noticeably thicken.
    10. THIN FILM EVAPORATION: Remove the liquid into Pyrex baking pan(s) putting NOT more than ¼ (.25) inch of liquid into the pan, cover with glass flat sheet to prevent it from boiling out of the Pyrex (these can be stacked in the oven, we use 4) and place in vacuum oven (no heat) and apply vacuum SLOWLY to 29 In. Merc. and the balance of the alcohol will boil off. Repeat the filling and purging process if necessary until all the liquid is evaporated and you have a thick oil remaining, if after an hour there is no more alcohol dripping into the cold trap or condenser then all the alcohol has been purged.** Make sure you have a cold trap connected between your oven and pump or connect your oven to the distillation column before pulling a vacuum (this is what is recommend, using the same columns and ice bath to recover any remaining solvent(s) with the distillation apparatus). **Hexane and alcohol will ruin the oil in your vacuum pump and stink up your work area.
    11. Test the Oil in the oven, If you can still taste the Hexane after step #10 when smoked, redislove the oil into fresh 190 proof Alcohol and purge in the oven again until the Hexane (Gasoline) taste and alcohol are gone.
    12. Never pull a vacuum on the oil mixture higher than 29.8 (at room temperature) or the cannabinoids will start to boil off as well(17c/68f @ 29.9). 29.8 is a lot however and many pumps will not go this far (29.5 max) but will easily get to the pressures necessary to vacuum distill and vacuum purge water or solvents.
    **Always Increase the vacuum pressure slowly, rapid decompression has the same result as increasing the heat rapidly and can result in the mixture boiling out of control. To stop the boiling simply stop or reduce the vacuum. **Always “lock off” your vacuum pump with a valve as they can “bleed” vacuum oil back up your vacuum tube (liquid or airisol) and into your PURE product when they are shut off and connected to a vacuum.

    We recovered 22g of pure oil or about 19.6%, no hexane taste, no waxes just clear thick oil. We recover about 97%+ of the solvents also. If you purge and distill reasonably carefully you can easily reuse your solvents.

    If your alcohol starts to smell like gasoline, there’s a lot of Hexane in it, probably just start with fresh as the “gasoline” taste is what you are trying to get rid of, this is a result of incomplete purge of the hexane stage, to fast or too much vacuum pressure, the boiling point of Hexane and Alcohol are quite different and can easily be separated, The amount of Hexane necessary to be able to be detected by smell is small and taste even smaller(>130ppm or less, target is >30ppm or less).

    This process will yield good high quality Oil if you take your time. The shortcuts through this process are expensive and don’t really impact yield or quality very much. Sure, you could add lots of equipment and cost but you will not get much cleaner or better product.

    Reply

    • Posted by Todd on January 14, 2016 at 8:25 AM

      If your serious about making oil get yourself a CO2 extractor. Much cleaner, easier and safer. No toxic petrochemicals used on the process either!!

      Reply

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