This is some very cool chemistry. And this post is dedicated to all of those who think that the organic chemistry you learned in your class was useless.
A professor and his graduate student at the University of Oregon have developed a hydrogen sulfide detector that can detect H2S in the parts per billion range (ppb). This detector would be very important in the study of biologically contaminated water samples. H2S is a colorless gas that smells like rotten eggs and is world-renown for its ability to make people sick.
This is very cool chemistry and it is performed using nucleophilic aromatic substitution. Most of you are familiar with electrophilic aromatic substitution from second semester class, so some of you may recognize nucleophilic aromatic substitution. Here is a quick example to refresh your memory.
In this reaction, methoxide anion is displacing fluorine in order to create the new aromatic ring. The defining characteristic of nucleophilic aromatic substitution is that you need electron withdrawing groups on your aromatic ring to make the reaction occur. In the above example, NO2 is our electron withdrawing group. I am not sure what they are using in their probe (spoiler alert: i have not red the article yet), but i am sure it is something similar.
The crux of the reaction, said the study’s graduate student Leticia A. Montoya, is the reaction process in which the probe reacts with H2S to produce a distinctly identifiable purple compound. “This method allows you look selectively at hydrogen sulfide versus any other nucleophiles or biological thiols in a system,” Montoya said. “It allows you to more easily visualize where H2S is present.”
The cite for JOC is: Leticia A. Montoya, Taylor F. Pearce, Ryan J. Hansen, Lev N. Zakharov, Michael D. Pluth. Development of Selective Colorimetric Probes for Hydrogen Sulfide Based on Nucleophilic Aromatic Substitution. The Journal of Organic Chemistry, 2013; :
Dr. Michael Pa
Dr. Michael Pa got a bachelors degree in chemistry from Binghamton University, a masters degree in organic chemistry from the University of Arizona and a Ph.D. in organic chemistry from the University of Arizona. His research focus was on novel pain killers which were more potent than morphine but designed to have fewer side effects. There may even be a patent or two that came out of it. Prior to all of this, he was a chemist at Procter and Gamble. After all of that, he (briefly) worked as a post-doctoral assistant at Syracuse University, working on novel organic light-emitting diodes (OLEDs). In between, he did NOT compete at the 1996 Olympics, make the Atlanta Braves opening day roster, or become the head coach of the Indiana Pacers, as he had intended. #fail During this entire time, he always loved helping students, especially if they were struggling with organic chemistry. In 2006, Dr. Pa founded AceOrganicChem.com in order to make learning organic chemistry fast and easy. 14 years and about 60,000 students later we are still helping students to learn organic chemistry one reaction at a time at https://www.aceorganicchem.com
