Types of Cannabinoids:
- Phyto-cannabinoids [produced or derived from the plant, Cannabis. Sativa.]
- Endo-cannabinoids [produced in the human body]
- Synthetic Cannabinoids [produced in a lab with a chemical structure that approximates the endocannabinoids we produce]
The scope of this post will only discuss the optimal temperature for “vaping” as it pertains to phyto-cannabinoids.
Phyto-cannabinoids: These extracts are non-psychoactive until sufficient heat is applied to cause a reaction known as decarboxylation.
The following are carboxylic, acid-containing, precursors to what we collectively refer to as cannabinoids. These acid precursors are the compounds produced by the plant C. Sativa.
- (Δ9 – THCA) Δ9 Tetrahydrocannabinoic Acid
- (CBDA) Cannabidiolic Acid
- (CBGA) Cannabigerolic Acid
- (CBCA) Cannabichromenic Acid
From these four precursors, 8 groups of cannabinoids can be produced through decarboxylation.
- (Δ9 – THC) Tetrahydrocannabinol
- (CBD) Cannabidiol
- (CBC) Cannabichromene
- (CBG) Cannabigerol
- (CBN) Cannabinol
- (CBL) Cannabicyclol
- (CBE) Cannabielsoin
- (CBT) Cannabitriol
Of the 86 cannabinoids identified, the majority of them can be categorized as structural analogs of one of the 8 compounds listed above. In other words, the majority of cannabinoids that have been identified approximate the molecular structure of one of the 8 compounds listed above.
The production of the 8 cannabinoid groups and their analogs is achieved through a chemical reaction known as decarboxylation. In the context of the carboxyl acid-containing precursors found in C. Sativa, decarboxylation involves the removal of a carbon atom from the carbon chain in the molecular structure of the acid.
What is Decarboxylation?
What this means is that the acid loses a carbon atom through a process called oxidation. When cannabis is heated, or burned, the atoms comprising the acid become agitated and begin to vibrate and bump into other atoms. In the context of smoking, or vaping, the atoms comprising the plant material or e-liquid begin to bump into the ambient oxygen molecules and bind with them.
The carboxyl group found on the acid-containing precursors of C. Sativa bind with the ambient oxygen once heat is applied, particularly at temperatures above 105 degrees Celsius. The byproduct of this is the formation of carbon dioxide (CO2).
What is left is a neutral cannabinoid that is accepted freely by the endocannabinoid receptors found on the surface of the cells in our body after we inhale the vapor or smoke.
Without undergoing a process of decarboxylation, the cannabinoic acids cannot be converted to cannabinoids that our body and cells can process. In other words, decarboxylation through oxidation converts the cannabinoic acids into compounds that are bioavailable to our cells.
It just so happens that heating, or burning, are the most popular ways to decarb cannabinoic acids, but the truth is that oxidation can be achieved without the presence of oxygen. In chemistry, the term oxidation has a more comprehensive definition, which is the loss or gain of an electron.
Oxidative increase, or decrease, depends on the electronegativity of a molecule or atom. In a very general sense, acids tend to be more positively charged than ambient oxygen. This means that from the outset, oxygen is primed to gain electrons and compounds like the cannabinoic acids are primed to lose electrons.
The protons in an oxygen atom are pulling electrons to the nucleus. Since the cannabinoic acids are positively charged, and carry an excess number of electrons, their electrons are susceptible to being pulled by the protons found in the oxygen atom. The electrons that are most susceptible to binding with oxygen from the cannabinoic acids belong to the carbon atoms in its molecular structure.
In other words, the cannabinoic acids, by virtue of their composition, are ready to decarb. When we introduce burning, or heating, we are catalyzing the oxidation of the cannabinoic acids. However, heating, or burning, is only one catalyst for decarboxylation. Chemists can achieve the same reaction through other means in a lab.
What does all of this have to do with “vaping”?
The issue is that the temperature at which carboxylic acids decarboxylate at an accelerated rate is 105 degrees Celsius. However, it is not clear whether or not the temperature required for decarboxylation is sufficient for “vaping”. A discussion about optimal temperature for “vaping” would require an assessment of the individual boiling points of each of the constituents found in an e-liquid, dry herb, and extracts.
Phyto-Cannabinoid Boiling Points
- Δ9 – THC: 157°C
- CBD: 160-180°C
- CBC: 220°C
- CBG: 52 MP
- CBN: 185°C
- CBL: N/A
- CBE: N/A
- CBT: N/A
- Δ8 – THC: 175-180°C
- THCV: <220°C
Terpenoid Boiling Points
- b-myrcene: 166-168°C
- b-caryophyllene: 119°C
- d-limonene: 177°C
- linalool: 198°C
- pulegone: 224°C
- 1, 8-cineole: 176°C
- a-pinene: 156°C
- a-terpineol: 217-218°C
- Terpineol-4-ol: 209°C
- p-cymene: 177°C
- borneol: 210°C
- Δ-3-carene: 168°C
Flavonoid and Phytosterol Boiling Points
- apigenin: 178°C
- quercetin: 250°C
- cannaflavin: 182°C
- b-sitosterol: 134°C
- Propylene Glycol: 188.2°C (boiling)
- Pure Glycerin/Glycerol: 290°C (boiling)
- Flavours: TBD
As you can see, the points at which each of these constituents sublimate differ greatly from each other, and all of them sublimate at a temperature higher than what is required to catalyze decarboxylation.
We need to determine the optimal temperature, or temperature range, for “vaping” and provide the justification for it.
In order to make that determination, there are a number of questions that need to be answered, and consensus achieved. They are as follows:
- Is 105°C the temperature at which cannabinoic acids decarboxylate at an accelerated rate? If not, what is the correct temperature?
- What are the thermodynamic properties of e-liquids, dry herb, and extracts, how do they heat up?
- What is the numerical distinction in temperature between vaporization and combustion for e-liquids, dry herb, and extracts?
- What constituents of the e-liquid, dry herb, or extract produce visible vapour, is the presence of a visible vapour necessary for “vaping” to work?
- Why do some “vape pens” produce more vapour than others, is it because they are heating the e-liquid, dry herb, or extracts to a higher temperature?
- Is it necessary to standardize, or regulate, how powerful a device can be, or to what temperature (max/min) an e-liquid, dry herb, or extract can be heated?
- Are there health risks associated with “vaping” at a higher vs. lower temperature?
- What are the implications on the e-liquid, dry herb, or extract (yield of cannabinoids) at higher vs. lower temperatures?
Authorship & Co – Authorship