Week 4:

This week, most of the seven groups repeated their experiment. For a couple, this week was the first time their experiment yielded acceptable results. For others, they had a chance to fine-tune already acceptable experimental results from Week 3. Several groups adjusted the scale of their experiment. We are working with “macroscale” glassware. Working with too small amounts it is rather easy to “lose” the product and end the experiment with disappointment. On the other hand, working with too large amounts is wasteful in time, money, and materials. Another issue, beside scale, that comes up often in synthetic experiments is, “How long should we run the reaction?” In my experience, an hour reflux is about the maximum that is reasonable for a Sophomore Organic Chemistry Laboratory experiment. Even an hour seems excessive at times. I assume that often we are working with “the law of diminishing returns.” The law of diminishing returns, in this case, informs us that most of the action is taking place at the beginning of the process. For example, a reaction may be %50 complete in 15 minutes, %90 complete in 30 minutes and %100 complete at the end of one hour. Is the extra half-hour worth the %10? Of course, the only way to really know what is going on in that reaction mixture is to monitor the progress of the reaction by TLC or some other means.

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