I am trying to understand the variables of decarbing under vacuum versus atmospheric pressure using flower material (not solvent extract). From my experiments, it seems that residual water in the material helps act as a barrier (raises activation energy?) and keeps the material at a lower temp versus the oven temps (I am not sure if that makes sense). My calculus is a little rusty, and I am just trying to make heads and tails of it all.
In a nutshell, what I am asking is there a relationship between heat, time and vacuum level as it relates specifically to Decarboxylation? I have placed finely ground cured material in a vacuum oven at 200F+ for 4 hours and it is still slightly damp to the touch. I would think that 15-20 minutes in a traditional convection oven would dry out the material quite well.
Any thoughts on what is going on?
http://thealchemistresource.thealchemistresource.com/p/82-decarboxylation.html
https://en.wikipedia.org/wiki/Decarboxylation
"Upon heating, Δ9-Tetrahydrocannabinolic acid decarboxylates to give the psychoactive compound Δ9-Tetrahydrocannabinol.[6] When cannabis is heated in vacuum, the decarboxylation of tetrahydrocannabinolic acid (THCA) appears to follow first order kinetics. The log fraction of THCA present decreases steadily over time, and the rate of decrease varies according to temperature. At 10-degree increments from 100 to 140 C, half of the THCA is consumed in 30, 11, 6, 3, and 2 minutes; hence the rate constant follows Arrhenius' law, ranging between 10−8 and 10−5 in a linear log-log relationship with inverse temperature. However, modelling of decarboxylation of salicylic acid with a water molecule had suggested an activation barrier of 150 kJ/mol for a single molecule in solvent, much too high for the observed rate. Therefore, it was concluded that this reaction, conducted in the solid phase in plant material with a high fraction of carboxylic acids, follows a pseudo first order kinetics in which a nearby carboxylic acid participates without affecting the observed rate constant. Two transition states corresponding to indirect and direct keto-enol routes are possible, with energies of 93 and 104 kJ/mol. Both intermediates involve protonation of the alpha carbon, disrupting one of the double bonds of the aromatic ring and permitting the beta-keto group (which takes the form of an enol in THCA and THC) to participate in decarboxylation.[7]"
Arrhenius Law
https://en.wikipedia.org/wiki/Arrhenius_equation
https://www.youtube.com/watch?v=3eBu2M975hE
https://en.wikipedia.org/wiki/Activation_energy
"In chemistry, activation energy is the energy which must be available to a chemical system with potential reactants to result in a chemical reaction.[1] Activation energy may also be defined as the minimum energy required to start a chemical reaction. The activation energy of a reaction is usually denoted by Ea and given in units of kilojoules per mole (kJ/mol) or kilocalories per mole (kcal/mol).
Activation energy can be thought of as the height of the potential barrier (sometimes called the energy barrier) separating two minima of potential energy (of the reactants and products of a reaction). For a chemical reaction to proceed at a reasonable rate, there should exist an appreciable number of molecules with translational energy equal to or greater than the activation energy."
In a nutshell, what I am asking is there a relationship between heat, time and vacuum level as it relates specifically to Decarboxylation? I have placed finely ground cured material in a vacuum oven at 200F+ for 4 hours and it is still slightly damp to the touch. I would think that 15-20 minutes in a traditional convection oven would dry out the material quite well.
Any thoughts on what is going on?
http://thealchemistresource.thealchemistresource.com/p/82-decarboxylation.html
https://en.wikipedia.org/wiki/Decarboxylation
"Upon heating, Δ9-Tetrahydrocannabinolic acid decarboxylates to give the psychoactive compound Δ9-Tetrahydrocannabinol.[6] When cannabis is heated in vacuum, the decarboxylation of tetrahydrocannabinolic acid (THCA) appears to follow first order kinetics. The log fraction of THCA present decreases steadily over time, and the rate of decrease varies according to temperature. At 10-degree increments from 100 to 140 C, half of the THCA is consumed in 30, 11, 6, 3, and 2 minutes; hence the rate constant follows Arrhenius' law, ranging between 10−8 and 10−5 in a linear log-log relationship with inverse temperature. However, modelling of decarboxylation of salicylic acid with a water molecule had suggested an activation barrier of 150 kJ/mol for a single molecule in solvent, much too high for the observed rate. Therefore, it was concluded that this reaction, conducted in the solid phase in plant material with a high fraction of carboxylic acids, follows a pseudo first order kinetics in which a nearby carboxylic acid participates without affecting the observed rate constant. Two transition states corresponding to indirect and direct keto-enol routes are possible, with energies of 93 and 104 kJ/mol. Both intermediates involve protonation of the alpha carbon, disrupting one of the double bonds of the aromatic ring and permitting the beta-keto group (which takes the form of an enol in THCA and THC) to participate in decarboxylation.[7]"
Arrhenius Law
https://en.wikipedia.org/wiki/Arrhenius_equation
https://www.youtube.com/watch?v=3eBu2M975hE
https://en.wikipedia.org/wiki/Activation_energy
"In chemistry, activation energy is the energy which must be available to a chemical system with potential reactants to result in a chemical reaction.[1] Activation energy may also be defined as the minimum energy required to start a chemical reaction. The activation energy of a reaction is usually denoted by Ea and given in units of kilojoules per mole (kJ/mol) or kilocalories per mole (kcal/mol).
Activation energy can be thought of as the height of the potential barrier (sometimes called the energy barrier) separating two minima of potential energy (of the reactants and products of a reaction). For a chemical reaction to proceed at a reasonable rate, there should exist an appreciable number of molecules with translational energy equal to or greater than the activation energy."
