Growing CBD Crystals

Based on my lab experiences, I had an idea in mind for how I would purify CBD. Now it is time to put my ideas to the test!

Finding the Supplies

Having never done any chemistry outside of a university or industrial setting, I was completely unfamiliar with how to get supplies on my own. I was thinking of ordering solvents online, but by pure luck, I stumbled upon a vendor in downtown Ypsilanti, right off of Michigan Ave, while I was getting some takeout. Right as I was about to get in my car and drive home, I saw a storefront display with a bright blue solution in a beaker stirring. I was really curious, so I went inside to see what was going on. The store, ambiguously named Ypsilanti Oil Company, had a bunch of chemistry supplies and equiptment. Located across from the Ypsilanti Farmers Marketplace, they are an “Aromatherapy Service” company, the idea being that someone would buy herbs from the farmers market and then be able to get the supplies to go home and make their own extracts. I saw that they had hexanes, so I bought a one quart (946 mL) bottle for $42.40.

Excited about my spontaneous purchase and ready to try some things, I obtained 1 gram of a 70% CBD extract from a local “provisioning center” for $60, and ordered a 12 pack of 1 dram (3.7 mL) vials from Amazon for $7.

Step 1. Dissolve the CBD extract in hexanes

For a spatula, I used a knife from a pumpkin carving toolkit because it was narrow enough to fit into the CBD sample and also the vials.

I did not have a scale or syringes, but I would estimate that I dissolved approximately 200 mg of the CBD sample in 1.5-2 mL of hexanes. In other words, I filled the 1 dram vial half full with hexanes, and then added two “scoops” like the one shown above, which was about 1/5 of the 1g sample. I did not use any heat to dissolve the sample, just a bit of stirring for a few minutes with the knife, until the solution was homogenous and clear. I did notice that there were some “dirt” particles that did not dissolve, so if I were to do this again on a larger scale, I would probably add a filtration step before growing the crystals.

Step 2. Freeze Overnight

I put the vial, tightly capped, in my freezer overnight. 24 hours later, I found some clear crystals!

Step 3. Decant and Collect

I waited an additional 24 hours to see if I could get more crystal growth, but it looked about the same the next day. I then waited for the solution to warm up to ambient temperature and decanted off the excess solvent, leaving behind the crystal solids shown below. For the decanted liquid, or the mother liquor, I am evaporating to increase saturation and re-freezing to see if I can grow a second batch. I plan on testing the crystal samples along with the original one to determine the extent of purity improvement. Also, in the future, I will look into how to get the best yield and mass recovery.

Overall, I was able to grow some CBD crystals using only one solvent (hexanes) and without any heat.

Cannabis Chemistry: Conversion of THC to CBD

CBDecomissioning THC

There are reported methods and patents for converting CBD into THC and for maximizing THC production, but what about the other way around? Could there be a way to convert psychoactive THC into non-psychoactive CBD?

Mechanisms for opening THC.

Looking at the structures of these cannabinoids, one can imagine a plausible mechanism to open up THC’s ether ring to the phenol of CBD. Fortunately, this kind of chemistry has been done before, and there are examples in the literature. Many molecules in nature have similar structures to THC and CBD because they are all part of a larger family of molecules called terpenoids, made from the same biochemical building blocks. So although the conversion of THC to CBD has not actually been reported, to my knowledge, there are conditions in the literature that are directly applicable to this transformation. Specifically, in 2012, the Baran synthesis group at the Scripps Research Institute in La Jolla, CA published a paper in JACS, where they synthesized diverse meroterpenoids from a boron-containing scaffold derived from sclareolide, a fragrant lactone found in sage. Their divergent and scalable synthesis allowed access to a wide variety of structures from nature, and also some synthetic analogues. Among the many reactions that they report, one of them is directly analogous to the conversion of THC to CBD: the conversion of chromazonarol to isozonarol.

Scaling up.

Usually, reactions done on a small scale (15 mg of starting material was used) are not directly applicable to an industrial scale without substantial effort. Since it was a final step, they did not need to optimize the reaction to be environmentally friendly or cost effective, as it was not a priority for the broad goals of this project. The conditions that they report (dichloromethane as solvent, -78 degree C temperature, BCl3 as a Lewis acid, 2,6-di-tert-butyl-4-methylpyridine as a bulky, more selective base), might not be directly scalable, especially for those with limited experience in synthetic chemistry.

Semisynthesis.

The field of natural product synthesis specializes in these types of transformations, to be able to convert one structure to another in order to access a natural product target either from simple commodity chemicals (total synthesis) or another natural product (semisynthesis). The conversion of THC to CBD would be classified as semisynthesis, since the starting material is another natural product – THC. Semisyntheses can have an advantage that the starting material is often similar in structure to the product, thus requiring fewer steps. However, some molecular targets cannot easily be accessed by semisynthesis, but their unique structure can be made from scratch, essentially, using organic chemistry methods to construct the scaffolds from chemical feedstocks. Both total synthesis and semisynthesis are used industrially for different purposes, and both strategies incorporate the same organic chemistry principles when designing a route.

The thought process.

As an important and necessary part of synthesis, reaction conditions are optimized using small amounts before scaling up; hypothesis-driven trial-and-error, or in some cases, high-throughput screening can be used to develop a more robust and ideal process. All factors of this reaction have the potential to be changed: the solvent, the Lewis acid, and the base. I would recommend, first, for a chemist to do this reaction with THC, using the same scale, reagents, and conditions as those in the paper. This would require access to a fume hood, to avoid exposure to the toxic reagents. After getting a sense of this, for example find out: what is the yield of CBD? How much recovered THC? Is any of the tetra substituted olefin formed? Then, the reaction conditions can be altered (time, temperature, equivalents) to increase yield, and a different solvent, Lewis acid, or base can be swapped to reduce toxicity and cost. This reaction optimization process may sound complex, and will definitely not be an easy problem to solve, but I know from experience, from a chemistry standpoint, this problem is solvable. With careful observation, organic chemistry intuition, and perseverance, there is no reason we cannot develop a method for converting THC into CBD, essentially “de-commissioning” a Schedule I substance.

Contact Us.

Orion GMP Solutions is a Pharmaceutical Process Engineering firm based out of Denver Colorado. We specialize in the implementation and auditing of GMP Cannabis Manufacturers to assist them in reaching international markets. If you would like to get more information, please send us an email at info@oriongmp.com.

This content was written and supported by Orion GMP Solutions.

Purification methods: Cannabinoid Recrystallization

Growing Crystals.

One pretty reliable recrystallization technique involves a mixed solvent system. For this, you will need two solvents of different strength: one that dissolves the molecules easily (Ethyl Acetate) and another that the molecules are mostly insoluble in (Pentane).

Experiment at a small scale.

A good working sample size is around 20-200 mg, and a 20 mL dram vial with a screwcap, or a small round bottom flask with a stopper are ideal. To the evaporated solid sample in the vial, a few mL of pentane are added and then broken up with a stirring rod or metal spatula, ideally sonicated, to produce a fine suspension of the solid. Then, with stirring and/or sonicating, Ethyl Acetate was added one drop at a time until the cloudiness dissipates to a clear, transparent solution. Let the vial sit at room temperature in an undisturbed ventilated area overnight, loosely capped, allowing a slow evaporation to occur. If crystals form in the next few days, they can be collected and washed with cold pentane.

The Layering Method.

If the evaporation leaves behind more of a residue, you can try a layering method. Re-dissolve the sample in the same way that you did before, but before you cap it, using a pipette, add a few mL of pentane slowly and carefully along the side of the vial to make a distinct layer on top. The crystals will form at this layer. Close the cap tightly this time, and let it sit undisturbed in a freezer for a few days. You can try several different ratios of solvent or temperatures. Once you figure out a method that works, you can try that on a larger scale. If your sample is not pure enough for recrystallization, other isolation methods, such a chromatography, may be necessary beforehand.

Contact Us.

If you’re interested in learning more about recrystallization as a method for purifying your extracts, CannaChemist can help. Contact us at info@oriongmp.com and let us help you.

This content is written and supported by Orion GMP Solutions, a pharmaceutical engineering firm dedicated to international standardization of GMP Cannabis.

Cannabis Chromatography

This short article describes the theory and basics of Cannabis Chromatography. CannaChemist has spent quite a bit of time patiently waiting for molecules to separate in chromatography columns used to purify organically synthesised columns, and shares her knowledge here to help you resolve products like THC from CBD rich tinctures.

Chromatography

Chromatography, or “color writing” is a reliable purification and analytical technique that has been used for over a century. In 1897, the American chemist David Talbot Day observed that crude oil turned into bands of color as it seeped upwards through clay. In 1900, the Russian-Italian chemist Mikhail Tsvete used chromatography for the separation of plant pigments such as chlorophyll (green), carotenes (orange), and xanthophylls (yellow). Chromatographic techniques continued to advance substantially, gaining widespread use and winning the 1952 Nobel Prize in Chemistry. Today, there are countless variations of chromatography and even automated instruments that are used by scientists around the world, making all kinds of research more efficient than ever.

It’s all about sand… Silicon Dioxide.

Chromatography is a way of separating and purifying all chemical compounds, not just colors, taking advantage of their differences in properties. More specifically liquid, column, or flash chromatography is a practical and straightforward way to purify a substance from a complex mixture (a natural extract or chemical reaction) by passing it through an inert solid called silica, or silicon dioxide. The different compounds in the mixture will have different degrees of attraction, or stickiness, to the silica, and will pass through it at different rates.

Silicon dioxide, a major constituent of sand, is a network of silicon oxygen bonds. The less polar, or more oily compounds will have less attraction to the polar silica, and come off of the column first. If you had a mixture of THC and CBD, the THC would elute first, since it contains only one alcohol functional group instead of the more polar CBD, which contains two. During this process, the compounds and the silica are dissolved in solvents such as pentane and ethyl acetate. The ratio of ethyl acetate to pentane is increased during the column to elute compounds of increasing polarity. However, this practice can be problematic for greasy nonpolar compounds such as terpenes, and even cannabinoids. If there is not enough attraction between the molecules and the silica, they will all travel quite quickly and elute together, not achieving a good separation.

Reversed Phase Chromatography.

Another form of chromatography, called reversed phase, can be used for these instances. A special hydrocarbon-coated silica is used, which reverses the elution order. Polar solvents such as water and acetonitrile (an organic solvent) are used. The ratio of acetonitrile to water is gradually increased during the run to draw the nonpolar compounds through the stationary phase. THC has greater attraction to the hydrophobic stationary phase, so CBD travels more quickly. If you are looking to remove lesser amounts of THC from a predominantly-CBD sample, reversed phase chromatography, although more expensive than untreated silica, is an ideal technique.

Contact Us.

If you’re interested in learning more about chromatography and separating cannabinoids, send us an email at info@oriongmp.com.

This content was written and supported by Orion GMP Solutions.

Chronic pain in the aged care setting

Medicinal Cannabis: A Therapeutic Alternative for Management of Chronic Pain in older Australians:

Presented by:

Leah Bisiani

MHlthSc/Dementia Consultant/RN.1.

“United in Compassion Symposium”, Melbourne, Australia. June 2017

Paper by Leah Bisiani

“Consider the present alternative, which is, we continue ignoring the significant benefits of cannabis, and refuse to contemplate the areas where traditional medicine is ineffectively managing critical conditions. We must provide a united front in advocating for medicinal cannabis as an innovative solution and a way forward within the realms of modern medicine by challenging and dispelling the myths and attitudes associated with cannabis, and sharing what we have recognized as the beneficial attributes associated with this plant”

Highlights:

Our commitment is to put the focus back on patients. Leah’s motivation regarding the emerging medicinal cannabis industry is to “challenge stigmas that have been propagated by judgmental perspectives of society related to negative stereotypical views, of which do not reflect the reality of the people we care for.”

Philosophy of Empathy and Compassion:

“Those who work within the medical and caregiving communities generally enter the health profession because of a belief in the alleviation of suffering for humanity. We aim to speak with empathy and compassion from the perspective of those who deserve to live a life free of suffering. Let us advocate for more empathetic approaches that will benefit our population, alleviate suffering, and maximize dignity, value, and quality of life. It is our responsibility to benefit our people, and to provide them with answers to identified problems and conditions, even and especially when these conditions do not respond to available medicine or practices.” Bisiani’s work is in “innovative approaches, thinking outside the box, and creating change, through the courage of our convictions. Actually, what I truly believe is there is no box,” says Bisiani.

Education is crucial:

Bisiani characterizes the situation well: “It’s real, it’s positive, it’s logical, and it’s humane. All change takes time, because making dreams a reality and anything worth fighting for, requires effort. Let us continue encouraging a solid and robust duty of care, that should be, at the very least, a baseline expectation within our medical community. We are creating a framework that enables current information for prescribers, patients, and society. We can reverse the stigma, and make it clear we are advocating exclusively for medicine through clinical based research, providing data and evidence for medicinal cannabis as a therapeutic alternative to non-effective regimes. Once provided, there will be a responsibility to honor these results or else be accused of denying assistance and permitting ongoing suffering and anguish. A multidisciplinary approach is required to enable an overall treatment plan to compliment the use of medical cannabis. Considerations of age, nutrition, environmental factors, lifestyle, can all be adjusted to maximize life quality first and foremost. Balance is what we aim for.”

The current landscape of pain in aged care:

“Pain is a fundamental and universal human experience, and thus access to effective pain relief should be regarded as an essential and universal human right. With the influx of baby boomers into the aged care community and an increase in life expectancy of our population, there is a growing need for more effective pain management regimes. Opioid analgesics are widely prescribed currently, yet these agents are associated with the highest degree of drug-related harm. The frequent and significantly dangerous adverse effects associated with opioids are detrimental to living safely, as they often predominantly affect mood, conscious thought, judgement, can create hallucinations and delusions, change cognition, and affect mobility. In relation to people living with dementia, these regimens can exacerbate the symptoms of dementia and potentially place them at higher risk of complications. Another huge issue regarding people living with dementia is that they may be unable to verbally express their pain. People living with dementia feel pain just as acutely as we do, and it is our responsibility to ensure their pain is managed, to avoid catastrophic events associated with acute delirium, behavioral expression and increased debility. It has been indicated that many geriatrics prescribed opioid pain management regimes are still not having their pain effectively managed. There is an urgent need for an alternative approach.”

An available solution:

The potential benefits of medicinal cannabis in treating poorly managed intractable chronic pain has been suggested as a beneficial alternative approach to enhancing quality of life and maximizing comfort and well-being in Australia’s older population. We are the ones with the drive and ability, so that we may revolutionize modern medicine in a way that creates a sustainable future for those in need. We are moving forward, and are fighting for what is right because we care on a level that is inundated with true compassion.

Paper by Leah Bisiani

CBD Recrystallization

Not all solids are created equal. Some molecules can be “more solid” than others. What does this mean? Well, certain kinds of functional groups on the molecule, such as the alcohol, or –OH group, are like little magnets that bind the molecules to each other and make them clump up as a solid. Sucrose, or table sugar, has eight alcohol functional groups. This gives it a crystalline structure and the ability to dissolve in strongly polar solvents such as water. The more –OH groups you have, relative to the overall molecule’s size and other properties, the more solid character the molecule possesses. CBD, or cannabidiol, has two alcohol groups, that is why it is called cannabi-di-ol, meaning “two alcohols”. On the other hand, THC only has one alcohol functional group. The other oxygen is an ether, which is less polar than an alcohol because it is not a hydrogen bond donor. Other portions of the molecule including the terpenoid portion, the benzene ring, and the pentane tail contribute hydrophobic character to the molecule, so even though alcohol groups are present, neither of these cannabinoids are polar enough overall to dissolve well in water, but organic solvents, such as ethanol and methanol will dissolve them more readily.

You might be thinking, a solid is a solid, so why does this matter? It matters for recrystallization. If you added just a small amount of solvent to a mixture of CBD and THC, which would dissolve more easily? The one that is less solid, the THC. If you have a mixture of CBD and THC already dissolved, which one will precipitate more easily? The one that is more solid, the CBD.

THC and CBD are both soluble in alcohol solvents, which is very useful for extraction, but for a recrystallization procedure, a solvent that is a little more selective about what it can dissolve is necessary. A less polar solvent, such as pentane, is needed so at the end of recrystallization the final product can be filtered and collected as a solid. Pentane is just a straight chain consisting of 5 carbons, a very nonpolar solvent. At room temperature, it doesn’t dissolve the cannabinoids well. For recrystallization, temperature control is the trick. When the pentane is near its boiling point (36C), it can actually dissolve the cannabinoids just from that extra input of kinetic energy, and when the solution cools back down to room temperature, which molecule do you think will precipitate first? The CBD!

Articles by CannaChemist are focused on concepts surrounding cannabis chemistry, both regarding the 400+ molecules present in the cannabis plant, and the chemicals typically used for processing and manufacturing cannabis products. These writings are for the purpose of educating and advising those that are striving to achieve GMP standards in the cannabis industry. The intention is that by increasing the knowledge of chemistry principles, you will be able to develop safer, more efficient, reliable, and inventive procedures for your cannabis manufacturing company.

No procedures or ideas developed based on these writings should be attempted without the same safety precautions that would be employed in an industrial or academic setting.