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Mmesoma Nwajagu
Looking for caffeine partition coefficients
In the answer elsewhere, Buttonwood has said what OP needs to know about partition coefficients and why they are not recorded for variety of organic solvents. Yet, I found these data (at $\pu{20 ^\circ C}$) in a published article (Ref.1):
The distribution coefficient $(K_\mathrm{d})$ of caffeine between an aqueous solution and organic solvents has been studied, and the influence of $\mathrm{pH}$ and temperature of the aqueous phase on the $K_\mathrm{d}$ of caffeine investigated in the caffeine—dichloroethane-water and caffeine-methylene chloride-water systems.
Since OP is looking to carry out a liquid-liquid extraction of caffeine from an aqueous phase to an organic phase, I thought following grapical representation of extraction would be helpful:
Here, $K =$ Partition coefficient or distribution coefficient; $W_o =$ Initial mass of solute; $V_1 =$ Volume of the organic layer in each extraction; $V_2 =$ Original volume of water; and $n =$ number of extractions.
The relationship is is given in:
$$\frac{\text{Final mass of solute in water phase} }{\text{initial mass of solute in water phase}} = \left(\frac{V_2}{V_2 + V_1K}\right)^n$$
References:
G. S. Klebanov, L. N. Mednikova, and A. D. Ovcharova, "Extraction of caffeine from aqueous solutions," Pharmaceutical Chemistry Journal1967, 1, 221-223 (DOI: https://doi.org/10.1007/BF00770195); Translated from: Khimiko-Khimiko-Farmatsevticheskii Zhurnal1967, (4), 49-52.
In the answer elsewhere, Buttonwood has said what OP needs to know about partition coefficients and why they are not recorded for variety of organic solvents. Yet, I found these data (at $\pu{20 ^\circ C}$) in a published article (Ref.1):
The distribution coefficient $(K_\mathrm{d})$ of caffeine between an aqueous solution and organic solvents has been studied, and the influence of $\mathrm{pH}$ and temperature of the aqueous phase on the $K_\mathrm{d}$ of caffeine investigated in the caffeine—dichloroethane-water and caffeine-methylene chloride-water systems.
Since OP is looking to carry out a liquid-liquid extraction of caffeine from an aqueous phase to an organic phase, I thought following grapical representation of extraction would be helpful:
Here, $K =$ Partition coefficient or distribution coefficient; $W_o =$ Initial mass of solute; $V_1 =$ Volume of the organic layer in each extraction; $V_2 =$ Original volume of water; and $n =$ number of extractions.
The relationship is is given in:
$$\frac{\text{Final mass of solute in water phase} }{\text{initial mass of solute in water phase}} = \left(\frac{V_2}{V_2 + V_1K}\right)^n$$
References:
G. S. Klebanov, L. N. Mednikova, and A. D. Ovcharova, "Extraction of caffeine from aqueous solutions," Pharmaceutical Chemistry Journal1967, 1, 221-223 (DOI: https://doi.org/10.1007/BF00770195); Translated from: Khimiko-Khimiko-Farmatsevticheskii Zhurnal1967, (4), 49-52.
Dichloromethane/ethyl acetate are not organic solvents for which the partition of an organic compound between water and an organic solvent are often recorded. More frequently these partitions are recorded for systems like water/1-octanol (example entry in the Dortmund Data Bank, requires an institutional subscription). Any change in the composition of the organic or/and aqueous phase (e.g., additional components, alteration of the pH value), or temperature obviously may affect $\log P$.
However, given the significance of these partitions for pharmaceutical compounds for their update, transportation, and excretion within the ADMET profile, there are programs providing a computed prediction as $c\log P$ data (some mentioned here), for example as extra plug-in of the Marvin sketcher, or as an independent application like the OSIRIS Property Explorer. Their prediction is based on a model about multiple hundreds of experimentally determined $\log P$ data with a wide range of chemical structures, aiming for a high correlation:
In the case of caffeine and the system water/octanol, DataWarrior predicts a $c\log P$ of $-0.18$, which is not terrible off from the report of $-0.21$ (median) and $-0.23$ (mean value, $n = 24$) by Harris and Logan.
The extraction of caffeine is an old lab class experiment. Murray and Hansen, for example, report a coefficient K for the partition between 1-propanol, and water/$\ce{NaCl}$ of 3.7. For a partition between chloroform and water, the same authors compare this with an estimate (based on solubility data listed in the Merck Index) of 8.3.
References:
Harris, M. F.; Logan J. L. Determination of log Kow Values for Four Drugs. J. Chem. Educ.2014, 91, 915–918; doi: 10.1021/ed400655b.
Murray, S. D.; Hansen, P. J. The Extraction of Caffeine from Tea: An Old Undergraduate Experiment Revisited. J. Chem. Educ.1995, 72, 851-852; doi: 10.1021/ed072p851.
Dichloromethane/ethyl acetate are not organic solvents for which the partition of an organic compound between water and an organic solvent are often recorded. More frequently these partitions are recorded for systems like water/1-octanol (example entry in the Dortmund Data Bank, requires an institutional subscription). Any change in the composition of the organic or/and aqueous phase (e.g., additional components, alteration of the pH value), or temperature obviously may affect $\log P$.
However, given the significance of these partitions for pharmaceutical compounds for their update, transportation, and excretion within the ADMET profile, there are programs providing a computed prediction as $c\log P$ data (some mentioned here), for example as extra plug-in of the Marvin sketcher, or as an independent application like the OSIRIS Property Explorer. Their prediction is based on a model about multiple hundreds of experimentally determined $\log P$ data with a wide range of chemical structures, aiming for a high correlation:
In the case of caffeine and the system water/octanol, DataWarrior predicts a $c\log P$ of $-0.18$, which is not terrible off from the report of $-0.21$ (median) and $-0.23$ (mean value, $n = 24$) by Harris and Logan.
The extraction of caffeine is an old lab class experiment. Murray and Hansen, for example, report a coefficient K for the partition between 1-propanol, and water/$\ce{NaCl}$ of 3.7. For a partition between chloroform and water, the same authors compare this with an estimate (based on solubility data listed in the Merck Index) of 8.3.
References:
Harris, M. F.; Logan J. L. Determination of log Kow Values for Four Drugs. J. Chem. Educ.2014, 91, 915–918; doi: 10.1021/ed400655b.
Murray, S. D.; Hansen, P. J. The Extraction of Caffeine from Tea: An Old Undergraduate Experiment Revisited. J. Chem. Educ.1995, 72, 851-852; doi: 10.1021/ed072p851.
In the answer elsewhere, Buttonwood has said what OP needs to know about partition coefficients and why they are not recorded for variety of organic solvents. Yet, I found these data (at $\pu{20 ^\circ C}$) in a published article (Ref.1):
The abstract of the paper states that:
Since OP is looking to carry out a liquid-liquid extraction of caffeine from an aqueous phase to an organic phase, I thought following grapical representation of extraction would be helpful:
Here, $K =$ Partition coefficient or distribution coefficient; $W_o =$ Initial mass of solute; $V_1 =$ Volume of the organic layer in each extraction; $V_2 =$ Original volume of water; and $n =$ number of extractions.
The relationship is is given in:
$$\frac{\text{Final mass of solute in water phase} }{\text{initial mass of solute in water phase}} = \left(\frac{V_2}{V_2 + V_1K}\right)^n$$
References:
In the answer elsewhere, Buttonwood has said what OP needs to know about partition coefficients and why they are not recorded for variety of organic solvents. Yet, I found these data (at $\pu{20 ^\circ C}$) in a published article (Ref.1):
The abstract of the paper states that:
Since OP is looking to carry out a liquid-liquid extraction of caffeine from an aqueous phase to an organic phase, I thought following grapical representation of extraction would be helpful:
Here, $K =$ Partition coefficient or distribution coefficient; $W_o =$ Initial mass of solute; $V_1 =$ Volume of the organic layer in each extraction; $V_2 =$ Original volume of water; and $n =$ number of extractions.
The relationship is is given in:
$$\frac{\text{Final mass of solute in water phase} }{\text{initial mass of solute in water phase}} = \left(\frac{V_2}{V_2 + V_1K}\right)^n$$
References:
More
VOTE
Dichloromethane/ethyl acetate are not organic solvents for which the partition of an organic compound between water and an organic solvent are often recorded. More frequently these partitions are recorded for systems like water/1-octanol (example entry in the Dortmund Data Bank, requires an institutional subscription). Any change in the composition of the organic or/and aqueous phase (e.g., additional components, alteration of the pH value), or temperature obviously may affect $\log P$.
However, given the significance of these partitions for pharmaceutical compounds for their update, transportation, and excretion within the ADMET profile, there are programs providing a computed prediction as $c\log P$ data (some mentioned here), for example as extra plug-in of the Marvin sketcher, or as an independent application like the OSIRIS Property Explorer. Their prediction is based on a model about multiple hundreds of experimentally determined $\log P$ data with a wide range of chemical structures, aiming for a high correlation:
(credit, "Calculated Compound Properties" about Property Explorer / DataWarrior)
In the case of caffeine and the system water/octanol, DataWarrior predicts a $c\log P$ of $-0.18$, which is not terrible off from the report of $-0.21$ (median) and $-0.23$ (mean value, $n = 24$) by Harris and Logan.
The extraction of caffeine is an old lab class experiment. Murray and Hansen, for example, report a coefficient K for the partition between 1-propanol, and water/$\ce{NaCl}$ of 3.7. For a partition between chloroform and water, the same authors compare this with an estimate (based on solubility data listed in the Merck Index) of 8.3.
References:
Harris, M. F.; Logan J. L. Determination of log Kow Values for Four Drugs. J. Chem. Educ. 2014, 91, 915–918; doi: 10.1021/ed400655b.
Murray, S. D.; Hansen, P. J. The Extraction of Caffeine from Tea: An Old Undergraduate Experiment Revisited. J. Chem. Educ. 1995, 72, 851-852; doi: 10.1021/ed072p851.
Dichloromethane/ethyl acetate are not organic solvents for which the partition of an organic compound between water and an organic solvent are often recorded. More frequently these partitions are recorded for systems like water/1-octanol (example entry in the Dortmund Data Bank, requires an institutional subscription). Any change in the composition of the organic or/and aqueous phase (e.g., additional components, alteration of the pH value), or temperature obviously may affect $\log P$.
However, given the significance of these partitions for pharmaceutical compounds for their update, transportation, and excretion within the ADMET profile, there are programs providing a computed prediction as $c\log P$ data (some mentioned here), for example as extra plug-in of the Marvin sketcher, or as an independent application like the OSIRIS Property Explorer. Their prediction is based on a model about multiple hundreds of experimentally determined $\log P$ data with a wide range of chemical structures, aiming for a high correlation:
(credit, "Calculated Compound Properties" about Property Explorer / DataWarrior)
In the case of caffeine and the system water/octanol, DataWarrior predicts a $c\log P$ of $-0.18$, which is not terrible off from the report of $-0.21$ (median) and $-0.23$ (mean value, $n = 24$) by Harris and Logan.
The extraction of caffeine is an old lab class experiment. Murray and Hansen, for example, report a coefficient K for the partition between 1-propanol, and water/$\ce{NaCl}$ of 3.7. For a partition between chloroform and water, the same authors compare this with an estimate (based on solubility data listed in the Merck Index) of 8.3.
References:
Harris, M. F.; Logan J. L. Determination of log Kow Values for Four Drugs. J. Chem. Educ. 2014, 91, 915–918; doi: 10.1021/ed400655b.
Murray, S. D.; Hansen, P. J. The Extraction of Caffeine from Tea: An Old Undergraduate Experiment Revisited. J. Chem. Educ. 1995, 72, 851-852; doi: 10.1021/ed072p851.
More
VOTE