1. DETERMINING REACTION RATES OF NITROAROMATIC REDUCTION REACTIONS Hayley Johnston Mentor: Ali Salter-Blanc Tratnyek Lab Summer 2013

2. Background Release of energetic munitions compounds into the environment leads to contamination Water Soil Sediments Selection of new energetic compounds Less shock sensitive (safer) Toxicity Environmental persistance

3. Objectives Determine the reaction rate of various nitroaromatic compounds in reducing conditions Formulate quantitative structure activity relationships (QSARs) Predict the behavior of current and future ammunitions contaminants in the environment 2,4,6-trinitrotoluene 2,4-dinitroanisole nitrobenzene 2,4-dinitrotoluene 4-chloro-1-nitrobenzene 1,3-dinitrobenzene

4. Reduction of Nitroaromatic Compounds (NACs) Reduction: an electron transfer reaction where the product gains electrons Overall Reaction 1 st Step Reduction by electron shuttle (mediator) High rate Moderate rate

5. Kinetics Generally assumed to be pseudo-first-order Reaction is second order in [Fe(II)P] and [NAC] rate= k FeP [Fe(II)P][NAC] [Fe(II)P] is constant so it can combine with the k FeP to get the k obs rate= k obs [NAC] Obtain second order rate constant (k FeP ) from k obs = k FeP [FeP]

6. Methods 60mL Reaction Vial containing: 25-400 μ L of 4.29mM iron(III) porphine (FeP) 1mL of 0.25M cysteine (to generate Fe (II)) 49mL Sodium Phosphate Buffer pH 7.0 50 μ L 0.1M nitroaromatic compound (NAC) 25 O water bath HPLC detection @ 254nm or 220nm Sampling frequency based on half life of NAC

7. Slope values are the observed reaction rate ( k obs ) for each reaction The k obs values are plotted against the concentration of FeP to obtain the k FeP value of each NAC Reduction Rates of 2,4-dinitrotoluene (DNT) by increasing concentrations of FeP

8. Complications New fit parameters Autocatalytic reaction? A→B A+B→C

9. Results First order fit is good up until ≈10 μ M NAC This enables me to obtain second order rate constants for each compound

10. Acknowledgements I would like to extend many thanks to: Ali Salter-Blanc Paul Tratnyek Vanessa Green Oregon Health and Science University (OHSU)