Electrochemistry
Here's some thoughts:
1. I categorize all reaction yields qualitatively.
2. I don't record yields on reactions less than 10 mg.
3. TLCs of reactions in SI
4. Yield ranges on multiple scales
5. Yield is not important.
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Electrochemistry
Reflecting on Yield, and the Need for a Qualitative Assessment of Reactions
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1. I categorize all reaction yields qualitatively.
What does this mean? Generally speaking, I don't really believe in yields other than 0%, 25%, 50%, 75%, or quantitative. I also sometimes break this down as 1.) Doesn't work, 2.) Works a little, 3.) Goes halfsies, 4.) Pretty alright, 5.) The bomb diggity. Now, I might conform to the standards of society and report a 62% yield for a publication or presentation, but for the purposes of a practicing-academic-chemist-grad-student, my breakdown is good enough. I readily acknowledge that this view of looking at yields is generally flawed, but it gets the job done on a day-to-day basis.
2. I don't record yields on reactions less than 10 mg.
This isn't entirely true. If I've rigorously run a reaction, and then repeated it, I'll believe a yield on 10 mg scale. But generally speaking, there are too many ways for the yield to go wrong: trace solvent, water, silica, or dust? add 10-20%. Did any manipulation of the material? subtract 10-20%. If I do record a yield on this scale, its most likely going to be as defined in section 1, rounded to the nearest 25%.
3. TLCs of reactions in SI
Why doesn't anyone do this? We record our TLCs in our notebooks and report Rf in the SI. But in my opinion, the TLC is the most important qualitative and rapid way to assess a reactions "goodness." If your reaction has an 75% yield, and an Rf = 0.40, but an inseparable side product at Rf = 0.37, then I hate your reaction (but I'll still use it if I need it). This is useful qualitative data! Far more useful than melting point. Believe it or not, you can optimize reactions on tiny scale by TLC alone. Its not ideal, but it definitely works when material is scarce.
4. Yield ranges on multiple scales
Reported at 95%! Awesome! Except, maybe that was the best yield you got out of 15 experiments, the reaction usually sits around 75% (and once you got a 30%). Maybe you know the reason for variabliliy (great! put it in the discussion), maybe you don't (thats ok too). Do good science: report yield ranges on multiple scales. If its not possible because its the front line of your 72-step linear synthesis, I forgive you. If its a methodology on simple starting materials, no excuses.
5. Yield is not important.
I'm use hyperbole for effect. But honestly, my yield doesn't ever really matter, in total synthesis there are two quantities of material: enough and not enough. There is a need in the literature to deemphasize the importance of yield. Its been said before that emphasizing yield is bad. If it were me, I would do so in favor of honest reporting of pros and cons of reactions, with a discussion of more qualitative aspects: ease of running and purifying, cost of catalysts, etc.
Those are my thoughts. Have a discussion. Or not. Now if you'll excuse me, I've got some scale-up to get back to.
- Tales From The Trenches: Pallambins
Our total synthesis of Pallambins C and D is out today in JACS. We have placed a summary of our failed approaches and strategies in the supporting information to give the reader a glimpse of what went into developing our synthetic route. Here...
- Making C–c Bonds With The Simplicity Of Making Amide Bonds
Despite all of the wonderful advances in organic synthesis, amide-bond formation is still the most widely used reaction among those making medicines. This truth has led some to declare their embarrassment and depression. Medicinal...
- An Adventure Into Nickel Cross Coupling Chemistry!
Here’s a behind the scenes look at one of our newest papers in JACS that highlights some nickel chemistry that we have developed! Phil has been interested for quite awhile now in transition metal cross-coupling methodology. A few ideas...
- Formal Olefin Hydroamination With Nitroarenes
Our latest work in the field of iron chemistry came out today in Science. First we would like to present a graph (shown below) on how this newly developed chemistry could simplify the synthesis of some biologically active intermediates: starting from...
- Functionalized Olefin Cross-coupling
Figure 1. Functionalized olefin cross-coupling at a glance. The last paper of the year from the inner depths of our lab has made its way out earlier today. It’s the bigger brother of our reductive olefin coupling paper from January. In a nutshell, reductive...