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.

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

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.

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. 

"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.

"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.

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;

1. A mechanical extraction process;

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

3. A chemical extraction process using the solvent carbon dioxide, provided that the process does not involve the use of high heat or pressure; or

4. Any other process identified by the Oregon Liquor Control Commission or the Oregon Health Authority, by rule.

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."

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

1. Isopropyl is ~20% less polar than Ethanol. This directly translates into ~20% less water soluble polar compounds dissolved into your oil, IE, water soluble chlorophyll.

2. Isopropyl is much faster in dissolving oils. The faster the extraction time, the less time is given to pull unwanted compounds.

• Isopropyl can remove 80% of the oils in 20 seconds at room temperature.

• Ethanol needs 3 minutes to accomplish the same thing.

3. Isopropyl has a magic power with table salt (This was used in RSO 2.0, not in RxCE).

• Adding table salt to Isopropyl separates the alcohol from water. Isopropyl forms the top layer, water forms the bottom. This is known as "Salting Out". Ethanol requires Potassium Carbonate to accomplish this, but it radically changes the water's pH which is beyond the scope of home extraction.

• "Salting Out" Isopropyl opened a new door to cleaner oil with the discovery of Brine Isopropyl Degumming. BID removes semi-polar phospholipids which bind water soluble compounds into your oil.  

4. One study shows conclusively that Isopropyl Alcohol 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.

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. 

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 Drizzle.life 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.

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."