Student Work

2010 coming Soon

 

2009

Keri Avery (Advisor: Cynthia McGowan)
Multi-Step Synthesis of Combretastatin A-4 Using Microwave Radiation

The use of microwave irradiation as a source of energy in organic synthesis can greatly reduce reaction time, increase product yield, improve efficiency and improve the purity of products.  Microwave techniques were applied to the multi-step synthesis of the compound Combretastatin A-4, a natural product found in the bark of the South African Bush Willow that has been shown to be an effective anti-tumor drug.  The synthesis involved a Knoevenagel condensation followed by bromination, elimination and Suzuki coupling reactions.  For some of the steps the results using microwave irradiation were compared to results using conventional synthetic procedures.  In the bromination step, microwave procedures produced higher yields and increased stereoselectivity.  The products of the reactions were characterized using Fourier Transform Infrared Spectroscopy (FTIR), ¹ H and ¹³ C Fourier Transform Nuclear Magnetic Resonance Spectroscopy (FTNMR) and  Gas Chromatography/ Mass Spectrometry (GC/MS).

  

Joseph Chiarelli (Advisor: Kathleen Swallow)
Analysis of Phenols in River Water Using Solid-phase Microextraction (SPME)

Solid-phase microextraction (SPME) was investigated as a method for extracting phenols from natural waters for analysis by gas chromatography/mass spectrometry (GC-MS). After testing a number of different fibers a SPME method for phenol extraction was developed and Limits of Detection (LOD) and mass recoveries were calculated. The method was applied to water samples from the Merrimack and Shawsheen Rivers and to samples collected at a polluted site along the Bega River in Romania. No detectable phenols were found in the local rivers tested. The SPME method was compared to a Spin-Bar Sorptive Extraction (SBSE) method using a Gerstel Spinner.  Low levels of phenols were detected in the Bega River samples using the Gerstel Spinners.

   

Julia Stein (Advisor: Stephen Theberge)
Detection of NSAIDs and Triclosan in Tap Water and Influent from a Wastewater Treatment Plant by Gas Chromatography-Mass Spectrometry (GC-MS)

Environmental scientists have recently become concerned with detectable concentrations of NSAIDs and other pharmaceuticals in tap water and wastewater.  Wastewater from the Lawrence, Massachusetts, treatment facility was analyzed to determine if these compounds were present and, if so, to what extent.  Samples were extracted using an Oasis HPL solid-phase extraction cartridge.  The analytes were derivitized using N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) with 1% trimethylcholosilane and analyzed by Gas Chromatography-Mass Spectrometry.  No detectable triclosan, naproxen or ibuprofen was found in any of the samples above the level of 1 part per billion.

 
2008

 

Stephanie Tanner (Advisor: Anthony Fernandez)
Analysis of the NMR Chemical Shifts of Iron(II) Complexes

It has been proposed that ¹ H NMR could be used to measure the electronic effects of a number of different phosphorous ligands on the iron(II) complex, Cp(CO)Fe(L)(COMe), where L is the ligand.  To assess this proposal, we analyzed the chemical shifts of the protons of the cyclopentadienyl ring and the methyl protons of the acyl group in a number of compounds with different ligands This approach was not successful because the differences were insignificant.  However, using ³¹ P NMR to measure the chemical shifts of the phosphorous ligands yielded results which did correlate with the electronic effects of the ligands.

 

2007

Natalya Atlasevich (Advisor: Kathleen Swallow)
Detection of Maillard Reaction Products Using Solid Phase Microextraction (SPME) and Gas Chromatography with Mass Spectrometric Detection (GC-MS)

 

The Maillard reaction is a browning reaction that occurs between amino acids and sugars at high temperatures. The reaction yields important flavor, aroma, and color compounds present in foods such as coffee, peanuts, and roasted meats. In this study, the Maillard reaction between glucose and glycine was studied at high temperatures and pressures. The two most abundant volatile compounds detected by GC-MS in the reaction products was 2,5-dimethylpyrazine and trimethylpyrazine. The quantitative analysis for these compounds was used to study the reproducibility of the SPME method and to calculate a partition coefficient between an aqueous solution and a SPME fiber for 2,5-dimethylpyrazine and trimethylpyrazine.

 

 

 

Christina Owen (Advisor: Stephen Theberge)
Validating Method Proficiency: Procedures for Extracting Gasoline Residues from Concrete Samples

 

Arson is one of the most difficult crimes in which to obtain a conviction. District Attorney Alan P. Kelley describes why a conviction is so difficult; “because you have to show that this person that you are trying to convict had essentially almost exclusive opportunity and exclusive motive, to get a conviction.” Scientifically speaking, the ability to prove if a sample came into contact with an ignitable liquid and what category of ignitable liquid was used is irrefutable. Each category of ignitable liquids has a very characteristic fingerprint produced when analyzed by gas chromatograph mass spectrometer (GC-MS).

The technique used to extract the ignitable liquid from fire debris samples is the most critical step in the analysis of evidence. Heating fire debris in the presence of an adsorbent, followed by elution is the most widely used method for evidence analysis. However, the current method for removing ignitable liquids from concrete uses a different adsorbent and returns insufficient results. The purpose of this research project is to validate the proficiency of sampling techniques which are used in the collection of ignitable liquid residues from concrete.

 

2006

Brian Provencher (Advisor: Cynthia McGowan)
A Novel Approach to 3-Pyrrolidones

Pyrrolidones constitute a class of chemical compounds
consisting of a five-membered heterocyclic ring containing nitrogen with a carbonyl in the ring. These compounds are known mostly for their use in hair care, oxidative hair dyes, wet wipes, lithographic printing and enzyme inhibition. Pyrrolidones have been used for pharmaceuticals and also have been investigated for use in transdermal drug delivery. In order for pyrrolidones to have so many different uses, the ring system must be highly substituted which is very hard to accomplish. Several different methods have been employed to synthesize highly substituted pyrrolidones.  By following a new scheme of brominating the central carbon of dibenzoylmethane, refunctionalizing the molecule, and then heating we were able to synthesize the triketone without using selenium dioxide. We have found that attempting to cyclize our pyrrolidone in triethylamine has given us less decomposition and cleaner NMR spectra then when we perform this reaction in an acidic solvent but we are still unsure of the structure or reaction pathway.

Keith Bartelson (Advisor: Anthony Fernandez)
Equilibrium Studies of an “Open Metallocene” with Isosteric Phosphorus Ligands

 
The goal of this research project was to investigate both the steric and electronic effects that may influence the equilibrium of the “open titanocene” phosphine ligands. To do this, an isosteric set of phosphorus (III) ligands, P(Me)2(p-XC6H4), were considered because they have a constant steric parameter, which would allow further investigation into the electronic effect. If a significant electronic effect is present in this equilibrium, more investigation must be done into the revision of the ligand cone angles for phosphorus (III) ligands. Several difficulties were encountered in the synthesis of the series of isosteric phosphorus ligands, but the best way to prepare them is now known. The first attempts at preparing the “open titanocene” were promising, but still need further work.