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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 is 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.

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136 Comments

  1. Nick

    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       Edit
      1. Nick

        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
        1. redturtle984

          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. redturtle984

    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. Rich

    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       Edit
    1. redturtle984

      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
    1. Skunk Pharm Research,LLC

      Start reading on page 741 in the Granny Storm Crow listings. http://www.letfreedomgrow.com/cmu/GSCListJan2014CONDITIONS.pdf GW

      Reply
  4. redturtle984

    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. https://vimeo.com/171020414

    Reply
  5. jlg5637

    When you get your finish product I would run it through a reflux still the smooth it off i can create or remove ant taste that way

    Reply       Edit
  6. peanutbutter

    I have a suggestion, GW. I've been thinking that I could take my pan of hexane extraction with the solution cooked down to about 10% of original volume. Spray a small amount of water into the solution and then freeze the mix. Should be able to filter off any ice then.

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  7. JP

    Hi GW, I may be in the wrong place for this post so I apologise in advance. I'm new to this procedure of making oil and am just totally confused as to what I need to do. I'm located in Ireland so getting equipment and solvents is very difficult here so I'm limited in what I can get my hands on. After reading this entire post and the different methods used can I ask if hexane can be used in this method:https://www.facebook.com/?_rdr#!/334801926611457/timeline/story?ut=3&hash=7180875461232508646&wstart=0&wend=1378018799&pagefilter=1&ustart&__user=100003697020689 Would following these steps produce a decent oil? Is there anything different that you would do here or wouldn't do. I was curious as to why the bud and alcohol is frozen, is this nessacery. The distiller I can get is the same as in the video but it's rated at 800watt, would that heat it up to much. Sorry for all the questions but I just want to do it right first time. Cheers

    Reply       Edit
    1. skunkpharmresearch

      You can do a hexane extraction without freezing the material or chilling the hexane, because hexane is non polar and mostly insoluble in water. It will do a good job, but I would be leery of using that distiller without knowing more about how its electrical components are set up. Hexane boils at 68-69C/155-156F, so no problems with the boiling range, but it is as flammable as gasoline, so the vapors are highly explosive. We distill off hexane in the lab using a simple boiling flask and water cooled condenser, which might be a safer way.

      Reply
      1. JP

        Thanks for the reply GW. In other comments in this thread people talk about using the hexane to do the extraction and then letting a fan blow over it until it evaporates, is it ready to be ingested after that or would sitting it on a hotplate on a low setting for a few hours be needed.

        Reply
        1. skunkpharmresearch

          A hexane extraction is harder than butane or ethanol to purge below sensory threshold, and at the very least, the pool needs to stay liquid so that the remaining solvent molecules can escape. Without vacuum, we typically have to redissolve in ethanol a couple of times and evaporate away the ethanol, to purge the remaining hexane.

          Reply
          1. ketones

            This is correct. Redissolving in a nontoxic solvent like ethanol (everclear or other high % spirit, you don't want to add water) several times, stirring, and evaporating will remove residual solvent. You'll also lose volatile flavor components of the oil but so it goes, thats why something like supercritical CO2 is preferred to a traditional solvent extraction.

            Reply
            1. skunkpharmresearch

              Tis true that extracting the volatile monoterpenes is easy with any number of solvents, but holding on to them during purge becomes more problematic the higher the boiling point of the solvent being used. Butane only has four carbons in the chain, while hexanes have six, so the Van der Waal forces and boiling point will be higher. One of the issues with the monoterpenes, is that they are alcohols, ethers, aldehydes, ketones, esters, and carboxylic acids themselves, with very high vapor pressures. It is because of this high vapor pressure at even ambient temperatures and far below their boiling points, that they can fill a room with molecules that collide with your noses. That is how skunky weed stinks up a room or car, even double bagged. The same heat that drives off the solvent, does doubly so with the monoterpenes. Hexane also extracts non polar waxes, we typically also winterize it using ethanol, so it gets a double whammy from a solvent evaporation standpoint, and tastes primarily of sesquiterpenes and the diterpene cannabinoids. That is one of the reasons that we use hexane for alchemy, but not for extractions other than in class as a demonstration. It

      2. Tom

        GW, You mentioned using a boiling flask and an condenser to reclaim the hexane. I plan on going this route and was wondering what size flask and condenser should I buy? Also, what would you recommend as far as a heater? I typically make batches of oil from 1/4 to 1lb of dry starting material. Just want to get this right the first time so I have to only order once! Thanks Tom

        Reply
        1. skunkpharmresearch

          We don't do much volume or huge batches, so we use a one liter flat bottom boiling flask, with a 24/40 taper on a stirring hotplate. You could also use a hot oil bath or sand bath or heating mantle to eliminate hot spots. We use a distillation elbow, with a 24/40 taper, and a Allihn or Graham, or Liebig condenser with the same taper, to reclaim the hexane and circulate coolant from a five gallon pail of ice water.

          Reply
  8. clean freak

    What materials are safe to use with hexane? I have a stainless steel trim pro with rubber fingers and a rubber gasket that I would like to clean. Will the steel and rubber hold up? Also what type of brush would be best? Thank you.

    Reply       Edit
    1. skunkpharmresearch

      The stainless is fine, but the rubber isn't. Cole Palmer's http://www.coleparmer.com/Chemical-Resistance is a good site to check out material compatibility on. You might consider using something like Viton for the fingers.

      Reply
  9. Zac

    Thanks for a great site! I was using crown VM&P naphtha for extracting and I checked the msds and it said it contained benzene in less than 101 ppm. They say that's not hazardous but I don't know if in terms of honey oil if that cause's any effect, is any level of benzene safe for making honey oil? Do you know how that would compare to a cigarette?

    Reply       Edit
  10. Samantha

    GW, Thank you for the extremely informative articles and website. It has inspired me to try a hexane wash. I was hoping you'd be kind enough to indulge a few questions. I have ~25grams of AVB (already vapped bud), which I was planning on doing the initial extraction with ethanol and the polish with hexane. My understanding is that ~50% of cannabinoids are left in AVB. If I assume a generous upper bound of 25% THC/cannabinoids originally in the pre-vapped bud, then I would expect to extract approximately 25g*0.50*0.25 or 3.125 grams of cannabinoids. Do you have any sense of the saturation point for cannabinoids in ethanol and hexane respectively? (At say, one atmosphere pressure and 20c.) I'm guessing that I'll need a larger volume of ethanol to adequately soak and to press an efficiently large percentage of the ethanol from the AVB, but I'm also curious from the perspective of making tinctures, etc. You recommend people evaporate their ethanol to reduce the volume so that it requires less hexane when polishing. Is this due to saturation issues, or just ensuring there's enough surface area when mixing the liquids to fully migrate the cannabinoids from the ethanol to the hexane? If it is the later, could this be mitigated by aggressively mixing or stirring the mixture, e.g., having the solution in a flash on a stirring plate for N minutes? Does one prefer their ethanol/hexane mixture shaken or stirred? :) What percentage of cannabinoids would one expect to be typically transferred? I was planning on purging the hexane using 200-proof ethanol wash and then evaporate the ethanol away. When vaporizing this final product, does one have to be concerned about purging ethanol as aggressively as hexane? While perhaps being less pleasant, is vaporizing small amounts of ethanol (which goes directly into the bloodstream) any more harmful than oral consumption? What sort of consistency can I expect out of my final product? I've inferred that this is partially dependent how decarboxylated the cannabinoids are? Is there any way to control the consistency? Previous "ethanol wash and evaporate" extractions I have done were a thick, very sticky and quite unwieldy paste. Any tips/suggestions for going from "lab glass" to storage container to consumption? Thank you for your attention, -Samantha

    Reply       Edit
    1. skunkpharmresearch

      Thanks for the good thoughts sisterwoman! There is no saturation point for mixing cannabis essential oils in either alcohol or hexane when simply mixing together, as they will blend at any ratio. The practical saturation point is probably around 30 to 50%, mol/mol, when extracting with either, as they become less aggressive as they load up with resin. You could do a cleaner extraction using simply hexane, instead of extracting with EtOH and washing with hexane. We extract large volumes with alcohol first, because of to the cost of HPLC reagent grade Hexane, which is more expensive than alcohol. Especially if using denatured alcohol or Iso. I shake my hexane mixture lightly to keep the boundary layers removed and fresh solvent at the resin interface. Not aggressively, as we don't want to fragment the material. Hexane tastes and smells like gasoline, which most folks can detect down to 130 ppm, which is less than half a percent of (0.52%) the Acute Oral Toxicity of (LD50): 25000 mg/kg (~ppm) [Rat], or the Acute Toxicity of the gas (LC50): 48000 ppm 4 hours [Rat] . Ethanol tastes and smells like booze down to about 100ppm and the Acute Oral Toxicity (LD50): is 3450 mg/kg (~ppm) [Mouse], with Acute Toxicity of the vapor (LC50): 39000 mg/m3 4 hours [Mouse]. As you can see, drinking Ethanol is actually more toxic to our bodies than Hexane. Hexane just doesn't have as pleasant a taste or effect. Once vaped material will be partially decarboxylated and will be of a soft oily consistency and is one of the stickiest substances known to nature. We draw it up into a glass syringe and inject it into the new storage container, while still hot. Don't try that with plastic syringes, as when it sets up, the piston cup will come off, before the plunger will withdraw, and with glass, you can heat it back up again easier.

      Reply
      1. Shawn

        Interesting enough finding a use for my ABV was how I got into extractions. I have had good luck doing QWET with ethanol, however when I started using denatured ethanol (I believe it is denatured with methanol and isopropyl) the liquid would become bright green. I have attempted using a denatured QWET twice, the second time I even baked (200F ~35min) the product longer, and both times it yields a very bright green product; very different from the amber color using pure ethanol. Is this due to the denaturing additives (the soak time was two minutes both times)? Unfortunately I was unable to remove the green color with a hexane/salt-water wash and separating funnel. I did my second pull of the second batch material with HLPC grade hexane and the filtered liquid is the same bright green even after washing :( Has anyone else had luck using denatured ethanol? Any ideas how to remove the green tint? The end goal is e-juice.

        Reply
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