drexel university researcher's report
DESCRIPTION
A 10-15 minute presentation on my research conducted in the chemistry department of Drexel University for students interested in participating in undergraduate research.TRANSCRIPT
Using the Abraham Model to Predict Organic Solubility to Determine a Recrystallization Solvent
Researchers’ ReportJanuary 16, 2013
Matthew McBrideUndergraduate Chemistry Major
Drexel UniversityBradley Research Group
Advantages of OpenNotebook Science for Undergraduate Research
Gain organization skills and learn how to properly present experiments
Receive timely feedback and corrective input
Documentation of a student’s contribution to a project
Organization and PresentationUpdating the log the day the experiment is performed requires a student to keep an organized record of the lab work
Eliminates long term reliance on handwritten notes and allows the log to be recorded when the experiment is still fresh in the student’s memory
(http://onschallenge.wikispaces.com/EXP324)
Organization and Presentation
Teaches a student how to identify the critical elements of an experiment
(http://onschallenge.wikispaces.com/EXP321)
Correction and InputUsing ONS allows the student to receive needed advice and guidance from the mentor directly on the experiment’s page
Allows the student to understand where an error was made and how to avoid repeating the mistake
(http://onschallenge.wikispaces.com/EXP255)
(http://onschallenge.wikispaces.com/EXP229)
DocumentationAllows a student’s work and contribution to a project to be documented
Provides graduate schools with the ability to view exactly what research an applicant has conducted
(http://onschallenge.wikispaces.com/list+of+experiments)
Solubility
Important when choosing a recrystallization solvent
Accurate solubility predictions for a compound allows the optimal solvent to be used
Preferred Solvent Characteristics
Does not react with the compound being recrystallized
High solubility at boiling point, but low solubility at room temperature
A boiling point that allows for easy drying of the product
Miscibility with water
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
Descriptors for a solute can be experimentally determined by measuring the solubility in 5 solvents
Descriptors for a solute can be predicted using AD Model003
Using the solute descriptors, the solubility in any of the solvents with known descriptors can be predicted
[William Acree](http://onschallenge.wikispaces.com/Benzoic+acid+-+Abraham)
Solubility PredictionsUsing 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/555548)
[Andrew Lang]
Solubility CurvesUsing 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]
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/exp324)
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)
Measuring Solubility with NMRCompare integration of solute and solvent peaks in saturated solutions using google app scripts1.5M Saturated solution of dibenzalacetone in THF
Dibenzalacetone
THF
(http://onschallenge.wikispaces.com/EXP308)[Andrew Lang]
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
[Andrew Lang]
ExampleThe 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]
DibenzalacetoneFirst recrystallized in ethyl acetate in 1906
Recrystallized in ethyl acetate in Organic Syntheses
(Straus and Ecker, Ber. 39, 2988 (1906))
Organic Teaching LabsMany 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)
SmartPhone AppThis 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)
SmartPhone AppEnter compound identification (SMILES, CSID, name…etc), and desired parameters
(http://onschallenge.wikispaces.com/recrystallization)
[Andrew Lang]
SmartPhone AppLists solvents and their predicted recrystallization yield
Prediction is generated by the temperature dependent solubility curves
(http://onschallenge.wikispaces.com/recrystallization)
[Andrew Lang]
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/models/solventselector.php?csids=555548)
[Andrew Lang]
Solubility at BoilingCannot be too low or an impractical recrystallization solvent
Developing a novel recrystallization method using 1-octanol (boiling point: 195°C) and then washing with pentane (boiling point: 35°C)
The ability to heat 1-octanol to higher temperatures increases the yield of the recrystallization
Designing reactions using solubility
These solubility tools can be used to choose a solvent for a reaction
Finding a solvent in which the reactants are soluble, but the product is insoluble. This allows the product to be recovered by a simple filtration
ExampleDerivatives of dibenzalacetone may be synthesized by altering the aldehyde used
From a library of derivatives, the following compound was the top hit for the docking site of Taxol
Uses phenanthrene-9-carboxaldehyde
(http://usefulchem.wikispaces.com/D-EXP022)
(http://www.chemspider.com/28190813)
[Andrew Lang]
Search Literature Perform a Reaxys© search to determine availability of synthesis procedures
No results
Synthesis PlanningDesire a solvent that the aldehyde is soluble in, but the product is not
The product was predicted as having very low solubility (<0.000M) in all solvents
NaOH used as the catalyst, so needs to be soluble in the solvent
(http://showme.physics.drexel.edu/onsc/models/solventselector.php?csids=28190813) [Andrew Lang]
Synthesis PlanningNaOH is soluble in methanol, so check aldehyde solubility
Phenanthrene-9-carboxaldehyde
SolventModel003 (M)
AD Measured (M)
Experimental (M)
BP (°C)
(http://showme.physics.drexel.edu/onsc/models/solventselector.php?csids=70806)
(http://www.chemspider.com/70806)
[Andrew Lang]
Synthesis Planning
Conclusion: Using methanol as the reaction solvent should allow the aldehyde be dissolved into solution, but will cause the product to precipitate
Synthesis
Created an approximately 0.016M solution of phenanthrene-9-carboxaldehyde in methanol
Added acetone and then a large excess of NaOH (catalyst) to the reaction mixture
Stirred mixture without heat over two days
(http://usefulchem.wikispaces.com/EXP286)
ProductReaction mixture:
(http://usefulchem.wikispaces.com/EXP286)
Crude Product Following suction filtration: 0.0834 g of yellow crystals
(http://usefulchem.wikispaces.com/EXP286)
Recrystallization Used benzene
Melting Point: 264-265°
(http://usefulchem.wikispaces.com/EXP286)
HNMRSpectrum of product
(http://usefulchem.wikispaces.com/EXP286)
16Hz Trans Coupling
Benzene peak in CDCl3
(http://www.chemspider.com/28190813)
[Andrew Lang]
SummaryOpen Notebook Science provides advantages to an undergraduate researcher
Measured and predicted solubilities can be used to optimize recrystallizations
Predicted solubilities can be used to plan the synthesis and optimize the recovery of the product
Further Information
http://onschallenge.wikispaces.com/
http://usefulchem.wikispaces.com/
http://onswebservices.wikispaces.com/