This blog lists that research that I have conducted as a part of the Bradley Research Group in the Chemistry Department at Drexel University and documents significant events in my young career as a scientist. I am participating in the Open Notebook Science Challenge for which I am performing experiments to measure the solubility of certain compounds (ex. carboxylic acids) in organic solvents. One of the goals of this challenge is to promote transparency in the scientific process. Every reported scientific finding is only as reliable or as meaningful as the steps incorporated to obtain that finding. This challenge requires that a detailed log of all steps completed in the experiment be recorded and posted in order that anyone attempting to repeat the experiment or desiring to better understand the meaning of the reported result is able to observe exactly what steps were carried out. From these solubility experiments, mathematical models are built to predict solubility. These models are used to choose recrystallization solvents and plan synthesis reactions. The products of these reactions are investigated as potential treatments for various diseases such as cancer and malaria.

Saturday, February 11, 2012

Winter Term Catch Up

When I first created this blog, I had been hoping to consistently post experiments as I completed them in the lab.  In the midst of classes and performing lab work, I have not been able to update this blog as much as I would have liked.  But now I will summarize what I have been working on recently:

I have completed a few more lab experiments using cinnamic acid to measure solubility as we continue to investigate the ability of the Abraham Model to predict solubility in organic solvents.  I measured the solubility of cinnamic acid in acetonitrile and attempted to measure the solubility in THF using the density method in EXP245.  The solubility obtained in the acetonitrile showed agreement with the Abraham model prediction (difference < 1M).  I was unable to measure the solubility in THF in this experiment due to not creating a saturated solution.

Most recently, I received training on NMR spectroscopy.  NMR stands for Nuclear Magnetic Resonance and is an extremely valuable method in organic chemistry for determining the structural and chemical make-up of a compound.  I have access to both a 300Hz and a 500Hz NMR machine.  NMR uses a powerful magnet to investigate the magnetic proper inherent to every atom of a compound.  In EXP255, I was able to perform my first experiment using NMR to measure the solubility of cinnamic acid in cyclohexanone and 1,2-dichloroethane.  In each case, the solubility predicted by the Abraham Model was extremely close and accurate to the experimentally measured value.  Using NMR for the solubility measurement was much faster and easier than the procedure required by the density method.  For my experiment, I used H1 NMR, which examines protons in a solution.  By looking at the resulting spectrum for each saturated solution of cinnamic acid in each solvent and by taking the integration under the curves, the solubility of cinnamic acid in each solvent was determined.

In addition to lab work, I have expanded my horizon for online research.  I have been introduced to Reaxys (the online data base can only be accessed while on Drexel's network or through a subscription), which allows compounds to be manually drawn or generated from their name or SMILES and then generates hits in literature based on the search criteria.  For example, I can enter a molecule and then check "melting point" and any piece of scientific literature present in the data base that has a melting point for the compound will come up as a hit.  This is a valuable way for quickly checking what research has been done on a compound for either verification purposes or just as a way to avoid needlessly repeating lab work.  One thing that must be consistently checked is that the stereochemistry of the compound is the same in the piece of literature as the compound being worked with.  At times, Reaxys will not indicate stereochemistry on the hits, so that must always been in consideration.

This is a brief update on what I have been investigating recently as I continue my winter term at Drexel and I hope to post soon in the future with other new scientific experiences!
Posted by at

No comments:

Post a Comment

Subscribe to: Post Comments (Atom)