Getting It Right the Second Time

This past week my Organic Chemistry students were instructed to repeat last week’s experiment (oxidization of a secondary alcohol to a ketone with household bleach). They were asked to change one variable that they thought would give a better outcome. I explained that in a real research environment chemical reactions are repeated several times to optimize them. For example, it is usually advantageous to maximize the yield of a reaction. It turned out that the previous experiment had an obvious flaw – the product was contaminated with residual acetic acid from the reaction mixture. This could be easily observed by a massive carboxylic acid peak on the IR spectrum of the product. The acetic acid peak was also apparent in the GC-FID chromatogram though not as pronounced. I was very impressed that a few students not only identified the problem, but came up a reasonable with a way to deal with it. This is a challenge that goes beyond simply following directions to complete an experiment successfully. I have wanted to do a series like this for a long time. Maybe I should be asking my students to repeat more experiments during the year. That way they would be performing the experiment the first time with an idea of how to improve it – sounds like research to me.

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