A presentation of my research involving using organic solubility predictions to optimize the process of choosing a recrystallization solvent. This research was conducted using Open Notebook Science to promote the sharing and access of the results and findings. This presentation was given as a 10 minute oral presentation for the 2013 COAS research day at Drexel University on April 9, 2013.

1. Using the Abraham Model to Predict
Organic Solubility to Determine a
Recrystallization Solvent
College of Arts and Sciences Research Day
Drexel University
Matthew McBride
Undergraduate Chemistry Major
Bradley Research Group
April 9, 2013

2. Open Notebook Science
Releases experiments and results
online in real time
Promotes the sharing and availability of
research
Provides all the details associated with
an experiment
Allows for “failed experiments” to be
available

3. Online Notebook
(http://onschallenge.wikispaces.com/EXP321)

4. Solubility
Amount of a solute (organic solid) that
can dissolve into a solvent (organic
liquid)
Important when choosing a
recrystallization solvent to obtain
maximum yield
Accurate solubility predictions for a
compound allows for the optimal solvent
to be used

5. Predicting Solubility with
Abraham Descriptors
Five descriptors for each solute and each solvent
The descriptors for over 80 solvents, including some
ethanol/water mixtures, are known
[William Acree](http://onschallenge.wikispaces.com/Benzoic+acid+-+Abraham)
Caffeine
Descriptors

6. Solubility Predictions
Using ONS Webservices, can list the predicted
solubility for a compound
Trans-dibenzalacetone
(http://showme.physics.drexel.edu/onsc/models/solventselector.php?csids=555548)
Solvent Model003
(M)
AD Measured
(M)
Experimental
(M)
BP
(°C)
(www.chemspider.com/55
5548)
[Andrew Lang]

7. Solubility Curves
Using a melting point, temperature dependent
solubility curves are generated
Assumes that at the melting point the compound is
miscible with the solvent
Solubility in Ethanol (Concentration M vs. Temperature °C)
(http://showme.physics.drexel.edu/onsc/models/solventselector.php?csids=555548)[Andrew Lang]

8. Temperature Controlled Shake
Flask Method
Add solute to the vials with the solvent and allow to
shake in the 25°C water bath
(http://onschallenge.wikispaces.com/e
xp324)

9. Temperature Controlled Shake
Flask Method
Measure the solubility using HNMR
Need to take two consecutive measurements without
the solubility changing to confirm the solution is
saturated
(http://onschallenge.wikispaces.com/EXP311)

10. Measuring Solubility with NMR
Compare integration of solute and solvent peaks in
saturated solutions using google app scripts
1.5M Saturated solution of dibenzalacetone in THF
Dibenzalacetone
THF
(http://onschallenge.wikispaces.com/EXP308)
[Andrew Lang]

11. Benefits of Solubility
Curves
These temperature dependent solubility
curves allow a solvent with the greatest
difference between solubility at room
temperature and at the boiling point to
be used
Reduces reliance on only recrystallizing
in solvents listed in literature
Optimizes the process of choosing a
recrystallization solvent

12. Example
The solvents used to recrystallize compounds in
organic teaching labs can be improved
Trans-dibenzalacetone
Aldol condensation between two molecules of
benzaldehyde and one molecule of acetone
(http://showme.physics.drexel.edu/onsc/reactionattempts/advancedsearch.php?compound=&solvent=&reactiontype
=&researcher=Matthew+McBride)
[Andrew Lang]

13. Dibenzalacetone
First recrystallized in ethyl acetate in 1906
Recrystallized in ethyl acetate in Organic Syntheses
(Straus and Ecker, Ber. 39, 2988 (1906))

14. Organic Teaching Labs
Many recrystallize in ethyl acetate
Is there a different solvent that could be used?
(http://classes.kvcc.edu/chm230/MIXED%20ALDOL%20CONDENSATION.pdf)
(http://www.xula.edu/chemistry/documents/orgleclab/Aldol_notes.pdf)

15. SmartPhone App
This app predicts the recrystallization yields of any
compound in different solvents using the solubility
curves:
Provides experimental and predicted values for
melting point and LogP
[Andrew Lang]
(http://onschallenge.wikispaces.com/recrystallization)

16. SmartPhone App
Enter compound identification (SMILES, CSID,
name…etc), and desired parameters
(http://onschallenge.wikispaces.com/rec
ation)
[Andrew Lang]

17. SmartPhone App
Lists solvents and their predicted recrystallization
yield
Prediction is generated by the temperature
(http://onschallenge.wikispaces.com/recrystalliz
ation)
[Andrew Lang]

18. Comparison
Ethyl acetate (predicted yield of 69%) vs ethanol
(predicted yield of 91%)
Ethyl acetate
Ethanol
0.09M
1.1M
0.62M
2.06M
(http://showme.physics.drexel.edu/onsc/m
odels/solventselector.php?csids=555548)
[Andrew Lang]

19. High Boiling Point Solvent
Recrystallize caffeine from 1-octanol (boiling point:
194°C) and wash with pentane (boiling point: 36°C)
Temperature curve for caffeine in 1-octanol (M vs. °C)
(http://showme.physics.drexel.edu/onsc/models/solventselector.php?csids=2424)

20. Recrystallization with 1-octanol
With a 0.25M solution, predicted recrystallization
yield is 92%
(http://onschallenge.wikispaces.com/EXP343)

21. Further Information
http://onschallenge.wikispaces.com/
http://usefulchem.wikispaces.com/
http://onswebservices.wikispaces.com/