Using Isopropyl Alcohol

Use Isopropyl to Safely Make RSO?  

If it's Legal Where You Live, Yes You Can!

Isopropyl Alcohol has a much maligned reputation for being dangerously toxic and at worst, cancerous. In all controversies, there are facts and there are opinions. Its the muddled in-between ground that has become a vortex of misinformation. First, a question is posed to be answered at the end, then the facts about Isopropyl Alcohol discussed. Knowing these facts will help frame the discussion around safely using Isopropyl, Acetone and Ethyl Acetate to make RSO/FECO. The safe use of these solvents has been a priority developing the RxCE process.  Basic summary - If you don't drink it, nor bathe in it, it will not hurt you. Drinking any solvent in volume, even Ethanol, is harmful to the human body. But as we shall see, the tables turn down at residual trace quantities.

AUTHORS NOTE:  So what is the purpose of this page? Think of this as being comparable to a shared needle program. People are out there using Isopropyl in unsafe ways. This page is to educate people on the science of Isopropyl and the RxCE extraction process, a means of safely using Isopropyl. In the United States, 55-60% of the population live in states where 190 proof ethanol is illegal to purchase but medical grade isopropyl is available. This is an effort to keep people safe when making their medications. Isopropyl, when used correctly, has a place in cannabis extraction.

Lets open this discussion with a question to be answered at the end of this page.

Answer below, but first, here is a collection of references from regulatory agencies, government agencies and scientists about the use and application of Isopropyl alcohol. These statements are quotes from official documents found on the U.S. Food and Drug Administration website, the U.S. National Institute of Health, Oregon and Colorado State websites, and other sources.

Isopropyl Alcohol, a.k.a., 2-Propanol, is an organic molecule with the formula of C3H8O. It is important to differentiate between Isopropyl and other products known as rubbing alcohol. Too often these two products are considered the same thing.  Rubbing alcohol is a product name that typically contain other compounds such as oils, perfumes and colors

Isopropyl is manufactured through means of a chemical reaction; whereas, Ethanol is created as the waste product of yeast. Yeast eats sugar, farts C02 and pisses alcohol. Isopropyl comes together something like Milton The Monster.   Nice picture, huh?

Note: You may encounter 1-Propanol on the FDA website.  1-Propanol is not Isopropyl Alcohol. It has the same set of atoms, but assembled into a different molecule, having different chemical characteristics. It's so different, it has a completely different manufacturing process. As a result, 1-Propanol is never sold under the name of Isopropyl Alcohol. The two are not interchangeable. The FDA has not approved 1-Propanol for food or topical applications, it has other uses.

How does Isopropyl compare to Ethanol?

Ethanol and Isopropyl Alcohol are nearly identical molecules. Isopropyl has one additional molecule composed of one carbon and two oxygen atoms. This additional molecule makes Isopropyl harder on the the human body, but not much more than ethanol. Both are known a Central Nervous System depressants and can lead to death through ingestion. Both solvents have a role in human health outside the body. Isopropyl and Ethanol both have emergency clinic overdose protocols

Your liver breaks Isopropyl down into Acetone. Is this a bad thing? 

Actually, this is a great thing!  This is why Isopropyl is safer than Ethanol at the trace levels. Your liver naturally produces Acetone when breaking down lipids which you burn as energy or is eliminated through urine or exhaling. Acetone is the simplest form of ketones. Here is what ChatGPT says about Keytones: 

"Ketones are a type of molecule that are produced by the liver when the body is low on glucose (sugar) and needs an alternative source of energy. The body can use ketones for energy when glucose is not readily available, such as during periods of fasting, low carbohydrate diets, or intense exercise.

Ketones can be used as a source of fuel for the brain and other organs in the body, and they can also be converted back into glucose by the liver to provide energy for the body's cells. This process is called gluconeogenesis.

In addition to their role in energy metabolism, ketones also have other potential benefits. For example, they may help to reduce inflammation in the body and improve cognitive function. Some studies have suggested that following a ketogenic diet, which is high in fat and low in carbohydrates, may have therapeutic benefits for certain medical conditions, such as epilepsy, type 2 diabetes, and certain types of cancer.

However, it is important to note that the body typically relies on glucose as its primary source of energy, and high levels of ketones in the blood can be a sign of a serious medical condition called diabetic ketoacidosis (DKA) in people with type 1 diabetes. As with any dietary or medical intervention, it is important to consult with a healthcare provider before making any changes to your diet or lifestyle."

Here is an exhaustive discussion published by the British Government on the effects of Acetone in the body.

Can you drink Isopropyl Alcohol?

Definitely not! Though it's not cancerous like Benzene or toxic like Methanol, it still is very harsh in the body even in low quantities. Its not a drink, its a solvent. If it trickles down your throat, it can hurt you. Don't do that!

At drinking volumes, Isopropyl will get you more inebriated than Ethanol with much more discomfort and pain. Every health clinic around the world has an Isopropyl Overdose protocol because this is a world wide problem. 

But down at the molecular level interesting enough, in trace quantities, the tables turn. Your liver breaks down Ethanol into Acetaldehyde, which after much exposure, causes Cirrhosis of the Liver, cancer and birth defects. On the other hand, Isopropyl is broken down into Acetone which is the simplest ketone uses as an energy source or expelled through urine and exhaling. 

Did you know your body creates Acetone when your liver breaks down lipids? Your body knows how to create and dissolve trace quantities through natural metabolism. This is why making RSO with Isopropyl is safe. You don't want to make a tincture out of Isopropyl, but there's no chance Isopropyl will hurt you within residual trace limits. There is nothing even remotely dangerous with trace quantities of Isopropyl in RSO. This is why the States of Alaska, Oregon, Colorado and Maine have legalized Isopropyl as a solvent in making Cannabis extract. 

Here is the NIH on medical training of Isopropyl Toxicity from a health care perspective. 

FDA has approved the use of Isopropyl in certain food ingredients. This means the FDA has approved trace amounts for human consumption effectively giving Isopropyl a semi-GRAS rating in limited applications. 






Subpart C - Solvents, Lubricants, Release Agents and Related Substances

Sec. 173.240 Isopropyl alcohol.

Isopropyl alcohol may be present in the following foods under the conditions specified:

(a) In spice oleoresins as a residue from the extraction of spice, at a level not to exceed 50 parts per million.

(b) In lemon oil as a residue in production of the oil, at a level not to exceed 6 parts per million.

(c) In hops extract as a residue from the extraction of hops at a level not to exceed 2.0 percent by weight: Provided, That,

(1) The hops extract is added to the wort before or during cooking in the manufacture of beer.

(2) The label of the hops extract specifies the presence of the isopropyl alcohol and provides for the use of the hops extract only as prescribed by paragraph (c)(1) of this section.

FDA has approved Isopropyl for topical use on the human body. 

"The only active ingredients used in OTC consumer antiseptic rub products that are eligible for consideration under the OTC Drug Review are ethyl alcohol (referred to subsequently as alcohol), isopropyl alcohol, and benzalkonium chloride."

Isopropyl is widely available in consumer products and is the primary antimicrobial found in many rubbing alcohol products, hand wipes, hand sanitizer sprays and gels. The CDC says that a minimum of 60% alcohol in hand sanitizer is required for effective use against COVID19.

FDA classifies solvents into three classes. Benzene in Class1, Methanol in Class 2, with Ethanol and Isopropyl (2-Propanol) in Class 3. Here's why that is so significant..

"Solvents in Class 1 (Table 1) should not be employed in the manufacture of drug substances, excipients, and drug products because of their unacceptable toxicity or their deleterious environmental effect.". 

"Solvents in Class 2 (Table 2) should be limited in pharmaceutical products because of their inherent toxicity.". 

"Solvents in Class 3 (Table 3) may be regarded as less toxic and of lower risk to human health. Class 3 includes no solvent known as a human health hazard at levels normally accepted in pharmaceuticals.".  

Benzene is a Class 1 solvent known to cause cancer. Proctor & Gamble has had many public product recalls in the Fall of 2021 due to residual amounts of Benzene in consumer hair care and skin products.

Methanol is a Class 2 solvent known for its toxicity making people go blind, even causing death. The FDA has published a list of banned hand sanitizers found to contain methanol.

Ethanol, Isopropyl alcohol, Acetone and Ethyl Acetate are FDA Class 3 solvents with low risk to human health. Only Ethanol is considered fully "GRAS", ie, "Generally Recognized as Safe" for human consumption. 

Isopropyl, Acetone and Ethyl Acetate have Semi-GRAS ratings, approved for human consumption in limited cases, as seen in Title 21, Chapter I, subchapter B, Part 173 - Secondary Direct Food Additives Permitted In Food For Human Consumption.

The State of Oregon approves Isopropyl as a solvent for Cannabis extraction.

In section OAR 845-025-3260 Cannabinoid Concentrate and Extract Processor Requirements,

(3) Cannabinoid Concentrates. A processor with an endorsement to make cannabinoid concentrates:

(a) May not:

(A) Use denatured alcohol.

(B) If using carbon dioxide, apply high heat or pressure.

(b) Must only use or store dry ice in a well-ventilated room to prevent against the accumulation of dangerous levels of carbon dioxide.

(c) May use:

(A) A mechanical extraction process; or

(B) A chemical extraction process using a nonhydrocarbon-based or other solvent, such as water, vegetable glycerin, vegetable oils, animal fats, isopropyl alcohol or ethanol.

(C) An extraction process using the solvent carbon dioxide, provided that the process does not involve the use of heat over 180 degrees (Fahrenheit) or pressure.

The City of Portland Oregon restates it clearly in 14B.130.020b:

B.  “Cannabinoid concentrates” means a substance obtained by separating cannabinoids from marijuana by;

The State of Colorado approves Isopropyl as a solvent for Cannabis extraction.

Here is Colorado's Marijuana Enforcement Dividsion code 5-315 section A.2 – Permitted Categories of Medical Marijuana Concentrate Production.

"A Medical Marijuana Products Manufacturer may also produce Solvent-Based Medical Marijuana Concentrate using only the following solvents: butane, propane, CO2, ethanol, isopropanol, acetone, heptane, ethyl acetate, and pentane. The use of any other solvent is expressly prohibited unless it is approved by the Division."

What is the benefit of using Isopropyl over Ethanol for making oil?

Isopropyl chemical properties are slightly different than Ethanol with these benefits:

Isopropyl is less polar than Ethanol meaning it extracts more Cannabinoids than Ethanol.

Isopropyl is almost 20% less polar than Ethanol because it has a dialetric constant of 18.2 vs Ethanol's 24.3. Here's a chart from a study that graphically shows the slight advantage Isopropyl has over Ethanol.

What Isopropyl products are safe to use?

That depends on how the alcohol is used whether for cleaning, sanitizing, or used in or on the body

A grading system has long existed in the chemical industry to designate levels of purity. Ethanol is available in multiple grades and so is Isopropyl alcohol. These grades range from from Technical Grade at the bottom, to ‘ACS Reagent Grade’ at the top. The bottles of Isopropyl Alcohol found at the neighborhood store are Technical Grade. 

Take a look at the grading system. For the consumer at home walking into a liquer store is the safe way to acquire ethanol. For other solvents, select the USP-NF and higher grades which have a purity guarantee

How should Isopropyl Alcohol be handled properly? 

Safety is paramount: NEVER distill near lit cigarettes, sparks or open flame as alcohol vapors are highly flammable. Always perform distillation in well-ventilated spaces using electric heat sources.

Exposure to solvents may occur during various stages of extraction. The primary risk involves direct skin contact when washing the plant. It's important to know that these solvents can dissolve skin oils leading to rapid skin dryness and cracking. Protection against skin contact is recommended using Neoprene or latex gloves.

Airborne exposure is a concern during bulk alcohol removal and the final reduction. When boiling off alcohol, the creation of airborne solvents poses both an exposure risk and a fire hazard. This risk can be mitigated by using a countertop moonshine still or an electric water distiller. Higher-end models like the Extract Craft Source Turbo, EtOH Pro, and Merlin400 also recapture alcohol vapors.

For those using an open boiler, it is imperative to operate in well-ventilated spaces to reduce the risk of inhaling dense fumes. The human olfactory point of detecting Isopropyl in the air is well below OSHA's Permissible Exposure Limits (PEL), but is not a good gauge to measure the density of the fumes. So to be safe, ALWAYS distill in well ventilated spaces using electric heat sources.

Here are  questions and arguments against using Isopropyl heard in social media:

Someone heard from others that 100% isopropyl will leave behind hydroxyl groups that are too difficult to purge because of their bond to the oils. Is that true?

I asked ChatGPT..

"The claim that 100% isopropyl will leave behind hydroxyl groups that are difficult to purge due to their bond to the oils is not accurate. Isopropyl alcohol (isopropanol) is a widely used solvent in various industries, including extraction processes. It is known for its ability to dissolve oils, resins, and other organic compounds effectively.

Isopropyl alcohol is a polar solvent, meaning it can break down polar substances like water and other hydrophilic compounds. It can also dissolve non-polar substances like oils and fats. During the extraction process, isopropyl alcohol can dissolve the desired oils, including cannabinoids, from the plant material.

However, it's important to note that thorough purging is necessary to remove any residual solvent and ensure a clean final product. Purging involves removing the solvent through evaporation or other methods to leave behind the desired compounds. The presence of hydroxyl groups or any other unwanted residues would depend on the quality of the extraction and the purging process, rather than the use of 100% isopropyl alcohol itself.

To achieve a high-quality extract, it's crucial to follow proper extraction and purification techniques, which may involve additional steps such as winterization, filtration, or vacuum drying. These methods help eliminate impurities and unwanted substances, ensuring a purer final product."

Step into our visual elevator!  We have a million floors to descend, all the way down into Parts Per Million.  

This illustration shows how Parts Per Million relates to the familiar items in our daily lives.  For instance, an average grain of rice is 29mg according to Google.  Do you buy Gummi bears at the Dispensary? 10mg is a common dose per bear. 

The FDA allows certain food ingredients to have PPM quantities of Isopropyl.  The seven lab tests presented below all come in under Oregon State's Limit of 5mg.  How lethal is Ethanol and Isopropyl?  About 1 cup of Isopropyl or 1.4 cups of Ethanol may be fatal to a 50c/110lb person.

(Hint: Right click on the image and open it in a new tab to see it at full resolution)

So, how did Isopropyl Alcohol become so maligned in our society?  

The answer begins with our parents telling us “Don’t drink that, it's poison!”. That served us well as children, but as adults having access to a world of information at our fingertips, we can easily find the truth. Reality is, you should never drink solvents, except of course water, which is the most polar solvent on earth. If you can wet your finger with a solvent, that is too much. Government regulation dictates the limits to stay within your body's ability to metabolize the solvent.The graphic above illustrates this scale. The only safe solvents that you can consume are at trace levels, well within the capacity of your liver and kidney's to metabolize them. 

When comparing the safety of GRAS ethanol and semi-GRAS isopropyl, things take an unexpected turn down at the trace level. At these levels, ethanol is revealed as a Dr.Jekyl/Mr Hyde where it is metabolized into carcinogenic Acetaldehyde which causes long term health effects. But trace quantities of Isopropyl, a.k.a. 2-Propanol, are broken down by your liver into Acetone, the simplest form of Ketones, used for energy or expelled from the body as a normal course of metabolism with no detrimental effects

As shown above, the FDA permits Isopropyl in certain spice ingredients to be consumed by humans. Just the mere fact it has FDA approval for limited food uses, says the whole story. As defined within government regulations, limits on trace amounts of Isopropyl fall well below the capacity of the liver and kidney's to metabolize these chemicals with no detrimental effects. 

If this were not true, the FDA would not allow it to be in food products. Rest assured, Isopropyl is not cancerous. If it were, it would be a Class 1 solvent. It does not cause blindness like Methanol, or it would be a Class 2 solvent. Isopropyl is listed with Ethanol as a Class 3 solvent "with low toxic potential to humans".

On dermal applications, Isopropyl is the normal disinfectant in hand sanitizer, hand wipes, and Rubbing Alcohol. The small amount of Isopropyl that gets absorbed through the skin is also metabolized by the liver to be consumed as energy or expelled in excess, with no detrimental effects.

One study conclusively proves Isopropyl extracts more cannabinoids than ethanol.

Bringing it Home.

Given the great fear that exists about Isopropyl’s toxicity, much time and effort has been spent in creating a robust procedure for eliminating residual Isopropyl from the oil. As with ethanol, heat over time is the catalyst that evaporates Isopropyl from the oil. The final reduction step is a literal firewall against unsafe trace levels remaining in the oil.  Multiple lab tests are presented below showing undetectable levels of Isopropyl in the RSO created using this process.

Basic summary on Isopropyl Alcohol's safety - if you don't drink it, nor bathe in it, it will not hurt you. Isopropyl Alcohol is a well known, well understood molecule, almost identical to Ethanol. FDA regulations and guidelines provide safeguards for limited use in food products and topical applications. 

Now, the answer the opening question..


Introductory Reading:

States That Permit Solvent Extraction:

                                                 Ethanol   Isopropyl  Acetone  Ethyl Acetate

..More to be listed soon.

Ethanol References:

Acetone References:

Isopropyl References:

Ethyl Acetate References:

Additional Reading:

All four solvents are NOT on the above list, but metabolites Acetaldehyde and Formaldehyde are.

Methanol References:

Heptane References

n-hexane Facts

Table of Solvent Properties - The Four Solvents, Safety Data Sheets Plus Plastics Chemical Resistance to Solvents

                      FDA    FDA GRAS  Dialetric   Boiling    Flash    Forms    Miscible    Chemical Resistance

            Class   Rating   Constant*1   Point     Point    Azeot.   W/Water    Nylon PP    PE    PET  HDPE

Ethanol       3       Y       24.3      78c/173f   14c/57f      Y        Y         A    A     A     A     A

Isopropyl     3       Y*2     18.2      82c/180f   11c/53f      Y        Y         D*3  A     B     A     A

Acetone       3       Y*2     20.7      56c/132f   -18c/0f      Y        Y         A    A     B     D     D

Ethyl Acetate 3       Y*2      6.0      77c/170f   -4c/24f      N        N         A    A     C     D     D

Further Reading on How to Understand Safety Data Sheets. 

*1 Dialetric Constant - The higher the #, the higher the polarity.

*2 Semi-GRAS approval given for limited uses. Isopropyl, Acetone, Ethyl Acetate

*3 SDS conflicts. Half rate an A, half rate a D.

Chemical Resistance:

Types of Plastics:

Nylon, PP=Polypropylene, PE=Polyethylene, PET=Polyethylene terephthalate, HDPE=High Density PolyEthylene,


A = Excellent.

B = Good -- Minor Effect, slight corrosion or discoloration.

C = Fair -- Moderate Effect, not recommended for continuous use. Softening, loss of strength, swelling may occur.

D = Severe Effect, not recommended for ANY use.

N/A = Information not available.

Lab Test Results during the development of the RSO 2.0 process reporting both Potency and Residual Solvents.

Lab Test Summary

The table plots the Total Cannabinoids reported in each test. Test #1 was run in May 2021 on standard RSO resulting in 34% Total Cannabinoids. The six subsequent tests were run with subsequent process improvements. The final test shows an increase to 79% cannabinoids with, Distillation, Rapid Winterization and the final reduction.

The seven lab tests can be seen below starting from most recent.

Lab Test #7 RICE Oil

This oil was made using Isopropyl for Extraction, then Distilled Water Distillation and Rapid Winterization.

Highest Yet - 79% Total Cannabinoids 

Lab Test #6 RECE Oil

This oil was made using Ethanol for Extraction, then Distilled Water Distillation and Rapid Winterization.

78% Total Cannabinoids 

Lab Test #5 12/22 - Test showing improvements using Silting in the RSO 2.0 2022 process.

This oil was made using a QWISO Dry Ice extraction, then Silting, Distillation, Winterization and final Reduction. Total Cannabinoids are just below the threshold of Distillates which start at 80%. Residual Solvents are undetectable.

Amazing! 78% Total Cannabinoids which is nearly Distillate Quality.

2-Propanol (IPA) again is undetectable.

Lab Test #4 02/22 - Isopropyl Alcohol and Brine Distillation. Residual Solvents are undetectable.

4th lab result during mid development stage. This test was the second to use Brine in the distillation rather than water. Potency is much better!

2-Propanol (IPA) is undetectable.

Lab Test #3 09/21 - Isopropyl Alcohol and Brine Distillation.  Residual Solvents are undetectable.

3rd lab result during mid development stage. This test was the first to use Brine in the distillation rather than water. Potency is much better!

2-Propanol (IPA) is undetectable.

Lab report #2 06-21 - Isopropyl and Water Distillation.  Residual Solvents are undetectable.

2nd lab result during early development stage. This test used water in the distillation rather than Brine. Potency is getting better!

2-Propanol (IPA) is undetectable.

Lab report #1 05/21 - Using Isopropyl Making Original RSO.  Residual Solvents are undetectable.

1st lab result during early development stage. This test used water in the distillation.

2-Propanol (IPA) is undetectable.

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WARNING: Never distill alcohol near open flame.  Alcohol vapors are highly flammable so always distill in well ventilated spaces.

This oil is appropriate for oral ingesting and vaping.  Due to the potential of residual salts, do not torch this oil.  Torch temperatures can reach over 760c/1400f and can vaporize any residual salts. 

Disclaimer:  Your use of any information or materials on the C.H.S. Website is entirely at your own risk, for which we shall not be held liable. It shall be your own responsibility to ensure safe use and operation of any processes, products, services or information made available through C.H.S publications and Website.

Revision History - Isopropyl Alcohol Controversy

24/03/02 Added a study that shows Isopropyl extracts more cannabinoids than Ethanol.

24/02/15 Corrected Ethyl Acetate stats 

23/12/26 Added section 'How should Isopropyl Alcohol be safely handled'.

                        Added section 'How does Isopropyl compare to Ethanol'.

                        Expanded links to FDA Semi-GRAS ratings for Isopropyl, Acetone and Ethyl Acetate.

23/12/04 Clarifying Acetone as a ketone. 

23/11/10 More polishing. 

23/11/04 More polishing. More detail about metabolites.

23/10/01 Page expansion in progress highlighted in red. Edits to continue..

23/02/27 Page expanded.

23/01/01 Page Published